DartFrame

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### List Datasets Example

Source: https://pub.dev/documentation/dartframe/latest/dartframe/HDF5ReaderUtil/listDatasets.html

Demonstrates how to use the `listDatasets` static method to get a list of all datasets within an HDF5 file. Ensure the HDF5 file exists at the specified path.

```dart
var datasets = await HDF5ReaderUtil.listDatasets('data.h5');
print('Available datasets: $datasets');

```

--------------------------------

### Read Bytes From File Example (Desktop)

Source: https://pub.dev/documentation/dartframe/latest/dartframe/FileIO/readBytesFromFile.html

Demonstrates how to read the byte content of a file using the readBytesFromFile method. This example assumes a desktop environment where dart:io is available.

```dart
var fileIO = FileIO();
var bytes = await fileIO.readBytesFromFile("/path/to/file.xlsx");

```

--------------------------------

### Example Usage of writeMultiple

Source: https://pub.dev/documentation/dartframe/latest/dartframe/HDF5Writer/writeMultiple.html

Demonstrates how to call the writeMultiple method with a map of dataset names to DataFrames. This example shows the intended usage for writing multiple datasets.

```dart
await HDF5Writer.writeMultiple('data.h5', {
  '/temperature': tempDf,
  '/humidity': humidityDf,
  '/pressure': pressureDf,
});

```

--------------------------------

### Example Usage of Series.str.get

Source: https://pub.dev/documentation/dartframe/latest/dartframe/StringSeriesAccessor/get.html

Demonstrates how to use the `get` method to extract the first element (index 0) from each list in a Series. This is useful when your Series contains lists and you need to access elements by their position.

```dart
var s = Series([['a', 'b'], ['c', 'd']], name: 'lists');
var first = s.str.get(0);
// Returns ['a', 'c']
```

--------------------------------

### Slice DataFrame with Custom Start and Step

Source: https://pub.dev/documentation/dartframe/latest/dartframe/DataFrameAdvancedSlicing/sliceRange.html

Select rows starting from a specific index with a custom step. This example selects every third row starting from the second row (index 1).

```dart
var result = df.sliceRange(start: 1, end: 10, step: 3);
// Returns rows 1, 4, 7
```

--------------------------------

### Save to File Example (Desktop)

Source: https://pub.dev/documentation/dartframe/latest/dartframe/FileIOBase/saveToFile.html

On desktop, provide the full file path as the first argument and the content as the second. Ensure the path is valid and the application has write permissions.

```dart
var fileIO = FileIO();
await fileIO.saveToFile("/path/to/file.txt", "This is some content.");

```

--------------------------------

### Get Top N Largest Values

Source: https://pub.dev/documentation/dartframe/latest/dartframe/DataFrameStatistics/nlargest.html

Use nlargest to retrieve the rows with the highest values in a specified column. This example shows how to get the top 3 scores.

```dart
var df = DataFrame.fromRows([
  {'Name': 'Alice', 'Score': 95},
  {'Name': 'Bob', 'Score': 87},
  {'Name': 'Charlie', 'Score': 92},
  {'Name': 'David', 'Score': 88},
]);

var top3 = df.nlargest(3, 'Score');
// Returns rows for Alice (95), Charlie (92), David (88)

```

--------------------------------

### Select Backend Example

Source: https://pub.dev/documentation/dartframe/latest/dartframe/NDArrayConfig/selectBackend.html

Instantiate NDArrayConfig.selectBackend with a shape and optional initial data to automatically determine the best storage backend.

```dart
var backend = NDArrayConfig.selectBackend(
  Shape([1000, 1000]),
  initialData: data,
);
```

--------------------------------

### Save to File Example (Desktop)

Source: https://pub.dev/documentation/dartframe/latest/dartframe/FileIO/saveToFile.html

Demonstrates saving content to a specified file path on a desktop platform.

```dart
var fileIO = FileIO();
await fileIO.saveToFile("/path/to/file.txt", "This is some content.");
```

--------------------------------

### Get Reference Type

Source: https://pub.dev/documentation/dartframe/latest/dartframe/ReferenceDatatypeWriter/referenceType.html

Accesses the current reference type. No setup or imports are required for this getter.

```dart
ReferenceType get referenceType => _referenceType;
```

--------------------------------

### Example Usage of openRandomAccess (Desktop)

Source: https://pub.dev/documentation/dartframe/latest/dartframe/FileIO/openRandomAccess.html

Demonstrates how to open a file for random access, set the position, read bytes, and close the file on a desktop environment.

```dart
var fileIO = FileIO();
var raf = await fileIO.openRandomAccess("/path/to/file.dat");
await raf.setPosition(100);
var bytes = await raf.read(50);
await raf.close();

```

--------------------------------

### NDArray toFlatList Examples

Source: https://pub.dev/documentation/dartframe/latest/dartframe/NDArray/toFlatList.html

Demonstrates how to use the toFlatList method to get a flattened list representation of an NDArray. Shows usage with 2D and 3D arrays, and the option to get a reference instead of a copy.

```dart
var arr = NDArray([[1, 2, 3], [4, 5, 6]]);
print(arr.toFlatList()); // [1, 2, 3, 4, 5, 6]

// Get reference (no copy)
var ref = arr.toFlatList(copy: false);

// 3D array flattened
var arr3d = NDArray([[[1, 2], [3, 4]], [[5, 6], [7, 8]]]);
print(arr3d.toFlatList()); // [1, 2, 3, 4, 5, 6, 7, 8]
```

--------------------------------

### Get vlenType Property

Source: https://pub.dev/documentation/dartframe/latest/dartframe/VlenDatatypeWriter/vlenType.html

Use this getter to retrieve the variable-length type. No specific setup is required beyond having an instance of the class.

```dart
VlenType get vlenType => _vlenType;
```

--------------------------------

### StorageBackend()

Source: https://pub.dev/documentation/dartframe/latest/dartframe/StorageBackend/StorageBackend.html

Constructs a new instance of StorageBackend.

```APIDOC
## StorageBackend()

### Description
Constructs a new instance of the StorageBackend.

### Method
constructor

### Endpoint
N/A

### Parameters
None

### Request Example
None

### Response
#### Success Response (Instance)
- **StorageBackend** (object) - A new instance of StorageBackend.

#### Response Example
```dart
var storage = StorageBackend();
```
```

--------------------------------

### Example of sliceReplace

Source: https://pub.dev/documentation/dartframe/latest/dartframe/StringSeriesAccessor/sliceReplace.html

Demonstrates how to use sliceReplace to substitute a part of a string with new content. The slice is defined by start and stop indices.

```dart
var s = Series(['abcdef'], name: 'text');
var replaced = s.str.sliceReplace(1, 4, 'XYZ');
// Returns ['aXYZef']

```

--------------------------------

### Get Parent Path Example

Source: https://pub.dev/documentation/dartframe/latest/dartframe/FileIOBase/getParentPath.html

Demonstrates how to use getParentPath to find the parent directory of a file. On web, this will return an empty string.

```dart
var fileIO = FileIO();
var parentPath = fileIO.getParentPath("/path/to/file.txt");
// Returns: "/path/to"
```

--------------------------------

### SmartLoader.initialize

Source: https://pub.dev/documentation/dartframe/latest/dartframe/SmartLoader-class.html

Initializes the SmartLoader with default data sources.

```APIDOC
## initialize()

### Description
Initializes the SmartLoader with default data sources.

### Method
`static void initialize()`
```

--------------------------------

### DataFrame abs() Example

Source: https://pub.dev/documentation/dartframe/latest/dartframe/DataFrameOperations/abs.html

Demonstrates how to use the abs() method to get the absolute values of numeric columns. Non-numeric columns are unaffected.

```dart
var df = DataFrame([
  [-1, -10],
  [2, -20],
  [-3, 30],
], columns: ['A', 'B']);

var result = df.abs();
// A: [1, 2, 3]
// B: [10, 20, 30]

```

--------------------------------

### connect Method

Source: https://pub.dev/documentation/dartframe/latest/dartframe/PostgreSQLConnection-class.html

Establishes a connection to the PostgreSQL database.

```APIDOC
## connect()

### Description
Establishes a connection to the PostgreSQL database.

### Returns
Future<void>
```

--------------------------------

### HeapManager Example Usage

Source: https://pub.dev/documentation/dartframe/latest/dartframe/HeapManager-class.html

Demonstrates how to create a HeapManager and allocate data in local and global heaps. Ensure necessary imports like 'dart:convert' for utf8.encode.

```dart
final heapManager = HeapManager(formatVersion: 0);

// Allocate in local heap for object names
final nameOffset = heapManager.allocate(
  HeapType.local,
  utf8.encode('dataset_name'),
);

// Allocate in global heap for large strings
final heapId = heapManager.allocate(
  HeapType.global,
  utf8.encode('large string data...'),
);

```

--------------------------------

### Create DTypeRegistry Instance

Source: https://pub.dev/documentation/dartframe/latest/dartframe/DTypeRegistry/DTypeRegistry.html

Use the factory constructor `DTypeRegistry()` to get the singleton instance. No setup or imports are required beyond the class definition.

```dart
factory DTypeRegistry() => _instance;
```

--------------------------------

### Registering and Using Data Sources

Source: https://pub.dev/documentation/dartframe/latest/dartframe/DataSourceRegistry-class.html

Demonstrates how to register a custom data source and find a handler for a given URI.

```APIDOC
## Example
```dart
// Register a custom source
DataSourceRegistry.register(S3DataSource());

// Find handler for a URI
final source = DataSourceRegistry.findByUri(Uri.parse('s3://bucket/data.csv'));
if (source != null) {
  final df = await source.read(uri, {});
}
```
```

--------------------------------

### Get Scheme Property - Dart

Source: https://pub.dev/documentation/dartframe/latest/dartframe/DataSource/scheme.html

Implement this getter to return the URI scheme your data source handles. Examples include 'http', 's3', or 'postgresql'.

```dart
String get scheme;

```

--------------------------------

### Get Column Data Example

Source: https://pub.dev/documentation/dartframe/latest/dartframe/DataCube/getColumn.html

Demonstrates how to use the getColumn method to retrieve a column and print its shape. Ensure the DataCube is initialized before calling this method.

```dart
var cube = DataCube.generate(3, 4, 5, (d, r, c) => d * 10 + r);
var col0 = cube.getColumn('col_0');
print(col0.shape); // [3, 4]
```

--------------------------------

### DataFrame Constructor Examples

Source: https://pub.dev/documentation/dartframe/latest/dartframe/DataFrame/DataFrame.html

Demonstrates creating DataFrames with specified columns and index, with default columns and index, and creating empty DataFrames.

```dart
final df1 = DataFrame(
  [
    [1, 'Alice', 100.0],
    [2, 'Bob', 200.0],
  ],
  columns: ['ID', 'Name', 'Score'],
  index: ['rowA', 'rowB'],
);
print(df1);
```

```dart
final df2 = DataFrame([
  [10, 20],
  [30, 40],
]);
print(df2);
```

```dart
final df3 = DataFrame(null, columns: ['X', 'Y']); // or DataFrame([], columns: ['X', 'Y'])
print(df3.columns); // Output: [X, Y]
print(df3.rowCount);  // Output: 0
```

--------------------------------

### Example Usage of toNDArray

Source: https://pub.dev/documentation/dartframe/latest/dartframe/DataCube/toNDArray.html

Demonstrates how to create a DataCube and then convert it back to an NDArray to inspect its shape. No special setup is required beyond creating the DataCube.

```dart
var cube = DataCube.generate(2, 3, 4, (d, r, c) => d * 10 + r);
var array = cube.toNDArray();
print(array.shape); // [2, 3, 4]
```

--------------------------------

### Example Usage of Series unique()

Source: https://pub.dev/documentation/dartframe/latest/dartframe/SeriesFunctions/unique.html

Demonstrates how to use the unique() method to get unique values from a Series. The order of elements is preserved, keeping the first occurrence.

```dart
var s = Series([1, 2, 3, 1, 2], name: 'numbers');
var unique = s.unique();
print(unique); // Output: numbers (Unique): [1, 2, 3]
```

--------------------------------

### connect Method

Source: https://pub.dev/documentation/dartframe/latest/dartframe/SQLiteConnection-class.html

Establishes the connection to the SQLite database.

```APIDOC
## connect()

### Description
Connects to the SQLite database using the provided connection string.

### Returns
Future<void> - A future that completes when the connection is established.
```

--------------------------------

### Resolve Path Example

Source: https://pub.dev/documentation/dartframe/latest/dartframe/FileIOBase/resolvePath.html

Demonstrates how to use resolvePath to combine a base path with a relative path. Note the behavior difference between desktop and web environments.

```dart
var fileIO = FileIO();
var resolved = fileIO.resolvePath("/base/path", "../other/file.txt");
// Returns: "/base/other/file.txt"

```

--------------------------------

### Get Access Pattern Implementation

Source: https://pub.dev/documentation/dartframe/latest/dartframe/ChunkedBackend/accessPattern.html

This getter retrieves the current access pattern by calling the _detectAccessPattern method. No specific setup is required beyond the class definition.

```dart
AccessPattern get accessPattern => _detectAccessPattern();
```

--------------------------------

### Example Usage of String Series Slice

Source: https://pub.dev/documentation/dartframe/latest/dartframe/StringSeriesAccessor/slice.html

Demonstrates how to use the slice method to extract substrings from a Series of strings. The start index is inclusive, and the stop index is exclusive.

```dart
var s = Series(['abcdef', '123456'], name: 'text');
var sliced = s.str.slice(1, 4);
// Returns ['bcd', '234']

```

--------------------------------

### Initialize HDF5FileBuilder

Source: https://pub.dev/documentation/dartframe/latest/dartframe/HDF5FileBuilder/HDF5FileBuilder.html

Use the constructor to create an instance of HDF5FileBuilder. It accepts an optional formatVersion parameter.

```dart
HDF5FileBuilder({
  int formatVersion = 0,
})
```

```dart
HDF5FileBuilder({int formatVersion = 0})
    : _writer = ByteWriter(),
      _addresses = {},
      _symbolTableWriter = SymbolTableWriter(),
      _dataLayoutWriter = DataLayoutMessageWriter(),
      _dataWriter = DataWriter(),
      _heapManager = HeapManager(formatVersion: formatVersion),
      _groupWriter = GroupWriter(formatVersion: formatVersion),
      _groups = {},
      _datasets = {};
```

--------------------------------

### Start, Stop, and Get Profiler Report

Source: https://pub.dev/documentation/dartframe/latest/dartframe/Profiler-class.html

Use Profiler.start() to begin timing an operation, Profiler.stop() to end it and record statistics, and Profiler.getReport() to retrieve a summary of all profiled operations.

```dart
Profiler.start('myOperation');
// ... perform operation ...
Profiler.stop('myOperation');

final report = Profiler.getReport();
print(report);

```

--------------------------------

### initialize

Source: https://pub.dev/documentation/dartframe/latest/dartframe/CompressionRegistry-class.html

Initializes the registry with a set of built-in compression codecs. This should typically be called once at the application's startup.

```APIDOC
## initialize()

### Description
Initialize registry with built-in codecs.

### Method Signature
`initialize() → void`
```

--------------------------------

### DataFrame sliceByLabelWithStep Example

Source: https://pub.dev/documentation/dartframe/latest/dartframe/DataFrameAdvancedSlicing/sliceByLabelWithStep.html

Demonstrates how to slice a DataFrame from a starting row label to an ending row label with a step of 2. Ensure the DataFrame is initialized with appropriate data and index.

```dart
var df = DataFrame.fromMap({
  'A': [1, 2, 3, 4, 5],
  'B': [10, 20, 30, 40, 50],
  'C': [100, 200, 300, 400, 500]
},
  index: ['a', 'b', 'c', 'd', 'e']
);

// Slice from 'a' to 'd', every other row
var result = df.sliceByLabelWithStep(
  rowStart: 'a',
  rowEnd: 'd',
  rowStep: 2
);

```

--------------------------------

### Initialize and use InMemoryBackend

Source: https://pub.dev/documentation/dartframe/latest/dartframe/InMemoryBackend-class.html

Demonstrates creating an InMemoryBackend with initial data and shape, then accessing and modifying a value.

```dart
var backend = InMemoryBackend([1, 2, 3, 4, 5, 6], Shape([2, 3]));
print(backend.getValue([0, 1]));  // 2
backend.setValue([1, 2], 99);

```

--------------------------------

### initialize static method

Source: https://pub.dev/documentation/dartframe/latest/dartframe/SmartLoader/initialize.html

Initializes the SmartLoader with default data sources. This is called automatically on first use, but can be called manually to ensure initialization happens at a specific time.

```APIDOC
## initialize()

### Description
Initializes the SmartLoader with default data sources. This is called automatically on first use, but can be called manually to ensure initialization happens at a specific time.

### Method Signature
`static void initialize()`

### Implementation Details
Registers built-in data sources: FileDataSource, HttpDataSource, ScientificDataSource, and DatabaseDataSource. Sets an internal flag to prevent re-initialization.
```

--------------------------------

### Example Usage of readSlice

Source: https://pub.dev/documentation/dartframe/latest/dartframe/Dataset/readSlice.html

Demonstrates how to read a slice of a 2D dataset, specifying start and end indices for rows and columns. Null for an end index indicates reading until the end of that dimension.

```dart
// Read rows 10-20 from a 2D dataset
final slice = await dataset.readSlice(
  reader,
  start: [10, 0],
  end: [20, null], // null means to the end
);

```

--------------------------------

### initialize static method

Source: https://pub.dev/documentation/dartframe/latest/dartframe/CompressionRegistry/initialize.html

Initializes the registry with built-in codecs. This method can only be called once.

```APIDOC
## initialize()

### Description
Initializes the registry with built-in codecs. This method registers `NoneCodec`, `GzipCodec`, and `ZlibCodec`, and sets `GzipCodec` as the default.

### Method
static void

### Parameters
None

### Implementation Details
- The method checks if the registry has already been initialized (`_codecs.isNotEmpty`). If so, it returns early.
- It then calls `register()` for each of the built-in codecs.
- Finally, it sets `_defaultCodec` to an instance of `GzipCodec`.
```

--------------------------------

### Example Usage of zfill

Source: https://pub.dev/documentation/dartframe/latest/dartframe/StringSeriesAccessor/zfill.html

Demonstrates how to use the zfill method to pad string Series with leading zeros. Ensure the Series contains strings that can be padded.

```dart
var s = Series(['1', '22', '333'], name: 'numbers');
var padded = s.str.zfill(5);
// Returns ['00001', '00022', '00333']
```

--------------------------------

### Get Every Nth Row with Offset

Source: https://pub.dev/documentation/dartframe/latest/dartframe/DataFrameAdvancedSlicing/everyNthRow.html

Use the everyNthRow method to select rows at a regular interval. Specify the step size 'n' and an optional 'offset' to determine the starting row.

```dart
var df = DataFrame.fromMap({
  'A': [1, 2, 3, 4, 5, 6, 7, 8, 9, 10]
});

// Every 3rd row
var result = df.everyNthRow(3);
// Returns rows 0, 3, 6, 9

// Every 3rd row starting from index 1
var result = df.everyNthRow(3, offset: 1);
// Returns rows 1, 4, 7

```

--------------------------------

### Example Usage of MATReader.readAll

Source: https://pub.dev/documentation/dartframe/latest/dartframe/MATReader/readAll.html

Demonstrates how to call the `readAll` method and access the loaded variables. Ensure the MAT file exists at the specified path.

```dart
final allData = await MATReader.readAll('experiment.mat');
print('Variables: ${allData.keys}');
print('Matrix A: ${allData['A']}');

```

--------------------------------

### Get String Datatype Class in Dart HDF5

Source: https://pub.dev/documentation/dartframe/latest/dartframe/StringDatatypeWriter/datatypeClass.html

Override the `datatypeClass` getter to return the HDF5 datatype class enum value. This example specifically shows how to return the string datatype class.

```dart
@override
Hdf5DatatypeClass get datatypeClass => Hdf5DatatypeClass.string;
```

--------------------------------

### Example Usage of DataCube tile

Source: https://pub.dev/documentation/dartframe/latest/dartframe/DataCubeTransformations/tile.html

Demonstrates how to tile a DataCube by repeating it along each axis. Ensure the input DataCube is initialized before tiling.

```dart
var cube = DataCube.zeros(2, 3, 4);
var tiled = cube.tile(depthReps: 2, rowReps: 1, colReps: 3);
// Shape becomes [4, 3, 12]

```

--------------------------------

### Save to File Example (Web)

Source: https://pub.dev/documentation/dartframe/latest/dartframe/FileIOBase/saveToFile.html

On the web, provide the content as the first argument and the desired filename as the second. The browser will typically prompt the user to download the file.

```dart
var fileIO = FileIO();
await fileIO.saveToFile("This is some content.", "file.txt");

```

--------------------------------

### Example Usage of resolveRegionReference

Source: https://pub.dev/documentation/dartframe/latest/dartframe/Hdf5File/resolveRegionReference.html

Demonstrates how to open an HDF5 file, obtain region reference data from a dataset, and then use `resolveRegionReference` to get information about the referenced region. Prints the address of the referenced dataset.

```dart
final file = await Hdf5File.open('data.h5');
final refData = ...; // Region reference data from a dataset
final refInfo = await file.resolveRegionReference(refData);
print('Referenced dataset at address: 0x${refInfo['address'].toRadixString(16)}');

```

--------------------------------

### connect method

Source: https://pub.dev/documentation/dartframe/latest/dartframe/MySQLConnection/connect.html

Establishes a connection to the MySQL database using a provided connection string. It parses the connection details, validates the scheme, and initiates the connection.

```APIDOC
## connect()

### Description
Establishes a connection to the MySQL database.

### Method Signature
Future<void> connect()

### Implementation Details
- Parses the connection string to extract host, port, username, password, and database name.
- Validates that the connection string scheme is 'mysql'.
- Throws a `DatabaseConnectionError` if the connection string is empty, invalid, or if the connection fails.

### Example Usage
```dart
final connection = MySQLConnection('mysql://user:password@host:port/database');
await connection.connect();
```
```

--------------------------------

### Apply Function to DataFrame Groups

Source: https://pub.dev/documentation/dartframe/latest/dartframe/GroupBy/apply.html

Use this method to apply a function to each group. The function should accept a DataFrame (representing a group) and return a DataFrame. This example demonstrates getting the first two rows of each group.

```dart
var result = df.groupBy2(['category']).apply((group) =>
  group.head(2)  // Get first 2 rows of each group
);
```

--------------------------------

### Slice.from(int start)

Source: https://pub.dev/documentation/dartframe/latest/dartframe/Slice-class.html

Creates a slice specification to select elements from a start index to the end. Equivalent to `[start:]`.

```APIDOC
## Slice.from(int start)

### Description
Selects elements from a specified start index to the end of the collection.

### Method
static SliceSpec from(int start)

### Parameters
#### Path Parameters
- **start** (int) - Required - The starting index (inclusive) for the slice.
```

--------------------------------

### Load and Write DataFrame Examples

Source: https://pub.dev/documentation/dartframe/latest/dartframe/DataFrameSmartLoader.html

Demonstrates loading DataFrames from different sources like CSV, JSON URLs, and custom datasets. Also shows writing DataFrames to CSV and JSON formats, with options for JSON orientation.

```dart
final df1 = await DataFrame.read('data.csv');
final df2 = await DataFrame.read('https://example.com/data.json');
final df3 = await DataFrame.read('dataset://iris');
```

```dart
await df.write('output.csv');
await df.write('output.json', options: {'orient': 'records'});
```

--------------------------------

### DataFrame Lead Method Example

Source: https://pub.dev/documentation/dartframe/latest/dartframe/DataFrameTimeSeries/lead.html

Demonstrates how to use the lead method to shift data forward by one or two periods. Newly introduced missing values are represented as null.

```dart
var df = DataFrame.fromMap({'A': [1, 2, 3, 4, 5]});
var led = df.lead(1);  // [2, 3, 4, 5, null]
var led2 = df.lead(2); // [3, 4, 5, null, null]
```

--------------------------------

### sampleWeighted Method Examples

Source: https://pub.dev/documentation/dartframe/latest/dartframe/DataFrameSamplingEnhanced/sampleWeighted.html

Examples demonstrating how to use the sampleWeighted method.

```APIDOC
## Example Usage

```dart
var df = DataFrame.fromMap({
  'item': ['A', 'B', 'C', 'D'],
  'weight': [0.1, 0.2, 0.3, 0.4]
});

// Sample 2 items with weights
var sampled = df.sampleWeighted(n: 2, weights: 'weight');

// Sample 50% with custom weights
var sampled2 = df.sampleWeighted(
  frac: 0.5,
  weights: [1, 2, 3, 4],
  randomState: 42
);
```
```

--------------------------------

### JsonReadError Usage Example

Source: https://pub.dev/documentation/dartframe/latest/dartframe/JsonReadError-class.html

Example demonstrating how to catch a JsonReadError when reading JSON data.

```APIDOC
## Example:
```dart
try {
  final df = await JsonReader().read('data.json');
} on JsonReadError catch (e) {
  print('Failed to read JSON: $e');
}
```
```

--------------------------------

### DataFrame Info Method Example

Source: https://pub.dev/documentation/dartframe/latest/dartframe/DataFrameInspection/info.html

Demonstrates how to use the info() method to display a summary of a DataFrame. This includes column names, data types, non-null counts, and memory usage.

```dart
var df = DataFrame.fromMap({
  'A': [1, 2, null, 4],
  'B': ['a', 'b', 'c', 'd'],
  'C': [1.1, 2.2, 3.3, 4.4],
});
df.info();
```

--------------------------------

### Example Usage of writeBytesToFile (Desktop)

Source: https://pub.dev/documentation/dartframe/latest/dartframe/FileIO/writeBytesToFile.html

Demonstrates how to use the writeBytesToFile method to save binary data to a file on a desktop environment. Ensure the 'bytes' variable is populated with the data to be written.

```dart
var fileIO = FileIO();
await fileIO.writeBytesToFile("/path/to/file.xlsx", bytes);
```

--------------------------------

### Custom Comparators Example

Source: https://pub.dev/documentation/dartframe/latest/dartframe/listEqual.html

Provides an example of how to define custom comparison functions for specific data types.

```APIDOC
### Custom comparators:
```dart
final customConfig = ListEqualConfig(
  customComparators: {
    DateTime: (a, b) => (a as DateTime).millisecondsSinceEpoch ==
                       (b as DateTime).millisecondsSinceEpoch,
  }
);
```
```

--------------------------------

### Get Unique Categories

Source: https://pub.dev/documentation/dartframe/latest/dartframe/CategoricalAccessor/unique.html

Returns unique categories from the data. Set `sort` to true to get sorted results.

```dart
List<dynamic> unique({bool sort = false}) {
  return _series._categorical!.unique(sort: sort);
}
```

--------------------------------

### Inspect Available Datasets

Source: https://pub.dev/documentation/dartframe/latest/dartframe/SmartLoader/inspect.html

This example shows how to inspect a 'dataset://' URI to retrieve a list of available datasets. It prints the 'available_datasets' property from the inspection result.

```dart
final datasets = await SmartLoader.inspect('dataset://');
print('Available datasets: ${datasets['available_datasets']}');
```

--------------------------------

### Implementing a Custom Data Source

Source: https://pub.dev/documentation/dartframe/latest/dartframe/DataSource-class.html

Demonstrates how to create a custom data source by extending the DataSource abstract class and implementing its core methods: `scheme`, `canHandle`, `read`, and `write`. It also shows how to register the custom data source with the `DataSourceRegistry`.

```APIDOC
## Implementing a Custom Data Source

To create a custom data source, extend the `DataSource` abstract class and implement the following:

- **`scheme`**: A getter that returns the URI scheme this data source handles (e.g., 'custom').
- **`canHandle(Uri uri)`**: A method that returns `true` if this data source can handle the given URI, `false` otherwise.
- **`read(Uri uri, Map<String, dynamic> options)`**: An asynchronous method that reads data from the source and returns a `DataFrame`.
- **`write(DataFrame df, Uri uri, Map<String, dynamic> options)`**: An asynchronous method that writes a `DataFrame` to the source.

After implementation, register your custom data source using `DataSourceRegistry.register()`.

```dart
class MyCustomSource extends DataSource {
  @override
  String get scheme => 'custom';

  @override
  bool canHandle(Uri uri) => uri.scheme == 'custom';

  @override
  Future<DataFrame> read(Uri uri, Map<String, dynamic> options) async {
    // Your implementation to read data
    throw UnimplementedError(); // Placeholder
  }

  @override
  Future<void> write(DataFrame df, Uri uri, Map<String, dynamic> options) async {
    // Your implementation to write data
    throw UnimplementedError(); // Placeholder
  }
}

// Register the custom data source
DataSourceRegistry.register(MyCustomSource());
```
```

--------------------------------

### Example Usage of toLatex

Source: https://pub.dev/documentation/dartframe/latest/dartframe/DataFrameExportFormats/toLatex.html

This example demonstrates how to use the toLatex method to export a DataFrame to a LaTeX table with a caption and label.

```APIDOC
### Example
```dart
var df = DataFrame([
  ['Alice', 25, 50000],
  ['Bob', 30, 60000],
], columns: ['Name', 'Age', 'Salary']);

var latex = df.toLatex(
  caption: 'Employee Data',
  label: 'tab:employees',
);

print(latex);
```
```

--------------------------------

### Example Usage of createReference

Source: https://pub.dev/documentation/dartframe/latest/dartframe/GlobalHeapWriter/createReference.html

Demonstrates how to allocate an object, write a collection, and then create a reference to that object using its ID and heap address.

```dart
final heapWriter = GlobalHeapWriter();
final objectId = heapWriter.allocate(utf8.encode('Data'));
final heapAddress = 2048;

// Write heap collection at address 2048
final collectionBytes = heapWriter.writeCollection(heapAddress);

// Create reference to the object
final reference = heapWriter.createReference(objectId, heapAddress);
// Use reference in dataset or attribute

```

--------------------------------

### Get Memory Usage

Source: https://pub.dev/documentation/dartframe/latest/dartframe/BackendStatsMixin/memoryUsage.html

Access the memoryUsage property to get an estimate of the memory used by the backend in bytes. This is an integer value.

```dart
int get memoryUsage;
```

--------------------------------

### Create HDF5 file for testing

Source: https://pub.dev/documentation/dartframe/latest/dartframe/NDArrayHDF5Reader/fromHDF5.html

This Python example demonstrates how to create an HDF5 file with a dataset named '/measurements' using the h5py library, which can then be read by the Dart `fromHDF5` method.

```python
import h5py
import numpy as np

data = np.random.rand(100, 200)
with h5py.File('data.h5', 'w') as f:
    f.create_dataset('/measurements', data=data)

```

--------------------------------

### SliceSpec Start Property Declaration

Source: https://pub.dev/documentation/dartframe/latest/dartframe/SliceSpec/start.html

Declares the nullable integer 'start' property for SliceSpec. Use this to specify the inclusive beginning index of a slice.

```dart
final int? start;

```

--------------------------------

### Convert PeriodIndex to DatetimeIndex

Source: https://pub.dev/documentation/dartframe/latest/dartframe/PeriodIndex/toTimestamp.html

Converts the `PeriodIndex` to a `DatetimeIndex` using either the start or end time of each period. Defaults to using the start time.

```dart
DatetimeIndex toTimestamp({String how = 'start'}) {
  final timestamps = _periods.map((p) {
    return how == 'start' ? p.startTime : p.endTime;
  }).toList();

  return DatetimeIndex(timestamps, name: _name, frequency: _frequency);
}
```

--------------------------------

### DataFrame.take() Examples

Source: https://pub.dev/documentation/dartframe/latest/dartframe/DataFrameSamplingEnhanced/take.html

Demonstrates selecting rows and columns using the `take` method. Supports positive and negative indices for rows and columns.

```dart
var df = DataFrame.fromMap({
  'A': [1, 2, 3, 4, 5],
  'B': [10, 20, 30, 40, 50]
});

// Take rows at positions 0, 2, 4
var result = df.take([0, 2, 4]);
// Returns rows 0, 2, 4

// Take columns at positions 0
var result2 = df.take([0], axis: 1);
// Returns only column A

// Take with negative indices (from end)
var result3 = df.take([-1, -2]);
// Returns last two rows

```

--------------------------------

### Example Usage of writeMultipleBlocks

Source: https://pub.dev/documentation/dartframe/latest/dartframe/LocalHeapWriter/writeMultipleBlocks.html

Demonstrates how to use writeMultipleBlocks when the heap data requires splitting into multiple blocks. This snippet shows the conditional check and subsequent sequential writing of blocks.

```dart
final heapWriter = LocalHeapWriter();
// ... allocate lots of data ...

if (heapWriter.needsMultipleBlocks) {
  final blocks = heapWriter.writeMultipleBlocks(2048);
  // Write each block to file sequentially
}
```

--------------------------------

### startTime property

Source: https://pub.dev/documentation/dartframe/latest/dartframe/Period/startTime.html

Retrieves the start time of the period. The exact start time is determined by the period's frequency (D for daily, M for monthly, Y for yearly).

```APIDOC
## startTime property

### Description

DateTime get startTime

Start time of the period.

### Implementation

```dart
DateTime get startTime {
  switch (_frequency.toUpperCase()) {
    case 'D':
      return DateTime(_date.year, _date.month, _date.day);
    case 'M':
      return DateTime(_date.year, _date.month, 1);
    case 'Y':
      return DateTime(_date.year, 1, 1);
    default:
      return _date;
  }
}
```
```

--------------------------------

### Get All Codec Names - Dart

Source: https://pub.dev/documentation/dartframe/latest/dartframe/CompressionRegistry/getNames.html

Call this static method to get a list of all registered codec names. Ensure the registry is initialized before calling.

```dart
static List<String> getNames() {
  initialize();
  return _codecs.keys.toList();
}
```

--------------------------------

### fromBinary static method

Source: https://pub.dev/documentation/dartframe/latest/dartframe/DataCubeImport/fromBinary.html

Imports a DataCube from a binary file. Note: This method is currently unimplemented and requires shape information.

```APIDOC
## fromBinary static method

Future<DataCube> fromBinary(
  1. String path

)

Import from binary file

### Description
Imports a DataCube from a binary file specified by the given path.

### Method Signature
`static Future<DataCube> fromBinary(String path)`

### Parameters
#### Path Parameters
- **path** (String) - Required - The path to the binary file to import.
```

--------------------------------

### Save to File Example (Web)

Source: https://pub.dev/documentation/dartframe/latest/dartframe/FileIO/saveToFile.html

Demonstrates saving content to a file with a specified filename on a web platform.

```dart
var fileIO = FileIO();
await fileIO.saveToFile("This is some content.", "file.txt");
```

--------------------------------

### Get Memory Recommendations

Source: https://pub.dev/documentation/dartframe/latest/dartframe/DataFrameMemoryOptimization/memoryRecommendations.html

Access the `memoryRecommendations` property to get a map of string keys to string values, where each entry represents a memory optimization suggestion.

```APIDOC
## memoryRecommendations property

### Description
Gets memory optimization recommendations for this DataFrame.

### Method Signature
`Map<String, String> get memoryRecommendations`

### Returns
A `Map<String, String>` containing memory optimization recommendations.
```

--------------------------------

### Create an Integer Range Index with AxisIndex.range

Source: https://pub.dev/documentation/dartframe/latest/dartframe/AxisIndex/AxisIndex.range.html

Use this factory constructor to create an AxisIndex with a specified length, starting from a given integer. The default start is 0.

```dart
var index = AxisIndex.range(10);  // [0, 1, 2, ..., 9]
```

--------------------------------

### GzipFilter Usage for Writing and Reading

Source: https://pub.dev/documentation/dartframe/latest/dartframe/GzipFilter-class.html

Demonstrates how to create a GzipFilter for writing with a specified compression level and how to create one for reading. The compression level is only relevant when encoding data.

```dart
// For writing with compression level 6
final filter = GzipFilter(compressionLevel: 6);
final compressed = filter.encode(rawData);

// For reading (compression level not needed)
final filter = GzipFilter.forReading(flags: 0, clientData: []);
final decompressed = await filter.decode(compressedData);

```

--------------------------------

### Example Usage of Hdf5File.close()

Source: https://pub.dev/documentation/dartframe/latest/dartframe/Hdf5File/close.html

Demonstrates the recommended pattern for closing an HDF5 file using a try-finally block to ensure cleanup.

```dart
final file = await Hdf5File.open('data.h5');
try {
  // ... use the file
} finally {
  await file.close();
}
```

--------------------------------

### toAtom Method Example Usage

Source: https://pub.dev/documentation/dartframe/latest/dartframe/DataFrameWebAPI/toAtom.html

An example demonstrating how to use the toAtom method to create an Atom feed from a DataFrame, specifying the necessary columns for titles and content.

```APIDOC
### Example
```dart
var atom = df.toAtom(
  title: 'Blog Posts',
  id: 'https://example.com/feed',
  titleCol: 'title',
  contentCol: 'body',
);
```
```

--------------------------------

### Get the last 5 rows of a Series

Source: https://pub.dev/documentation/dartframe/latest/dartframe/SeriesFunctions/tail.html

Use the tail() method without arguments to get the last 5 rows. The default value for n is 5.

```dart
var s = Series([1, 2, 3, 4, 5, 6, 7, 8, 9, 10], name: 'numbers');
var last5 = s.tail();
print(last5); // Output: numbers: [6, 7, 8, 9, 10]
```

--------------------------------

### connect

Source: https://pub.dev/documentation/dartframe/latest/dartframe/MySQLConnection-class.html

Establishes a connection to the database.

```APIDOC
## connect()

### Description
Establishes a connection to the database.

### Returns
- Future<void> - A future that completes when the connection is established.
```

--------------------------------

### fromFile static method

Source: https://pub.dev/documentation/dartframe/latest/dartframe/DataCubeImportExtension/fromFile.html

Creates a DataCube from a file, automatically detecting the file format.

```APIDOC
## fromFile static method

### Description
Create DataCube from file (auto-detect format)

### Signature
```dart
static Future<DataCube> fromFile(String path)
```

### Parameters
#### Path Parameters
- **path** (String) - Required - The path to the file to import.
```

--------------------------------

### Get First 5 Rows of a Series

Source: https://pub.dev/documentation/dartframe/latest/dartframe/SeriesFunctions/head.html

Use the head() method without arguments to get the first 5 rows. The default value for n is 5.

```dart
var s = Series([1, 2, 3, 4, 5, 6, 7, 8, 9, 10], name: 'numbers');
var first5 = s.head();
print(first5); // Output: numbers: [1, 2, 3, 4, 5]
```

--------------------------------

### Get Codes Property Implementation

Source: https://pub.dev/documentation/dartframe/latest/dartframe/MultiIndex/codes.html

Retrieves a deep copy of the internal codes. Use this to get the list of codes without modifying the original internal list.

```dart
List<List<int>> get codes => _codes.map((c) => List<int>.from(c)).toList();
```

--------------------------------

### Initialize DCFReader

Source: https://pub.dev/documentation/dartframe/latest/dartframe/DCFReader/DCFReader.html

Use this constructor to create a new DCFReader instance, providing the path to the DCF file.

```dart
DCFReader(this._path);
```

--------------------------------

### List Datasets Implementation

Source: https://pub.dev/documentation/dartframe/latest/dartframe/DCFUtil/listDatasets.html

This implementation shows how to use DCFReader to open a file, list its datasets, and ensure the reader is closed afterward. It's essential to handle potential exceptions during file operations.

```dart
static Future<List<String>> listDatasets(String path) async {
  final reader = DCFReader(path);
  await reader.open();
  try {
    return reader.listDatasets();
  } finally {
    await reader.close();
  }
}
```

--------------------------------

### SliceSpec Constructor

Source: https://pub.dev/documentation/dartframe/latest/dartframe/SliceSpec/SliceSpec.html

Constructs a SliceSpec object to define slicing parameters. Allows specifying start, stop, and step indices for inclusive start and exclusive stop slicing.

```APIDOC
## SliceSpec Constructor

### Description
Creates a slice specification with optional start, stop, and step parameters.

### Parameters
#### Positional Parameters
- **start** (int?) - The starting index (inclusive). If null, it represents the beginning.
- **stop** (int?) - The stopping index (exclusive). If null, it represents the end.

#### Named Parameters
- **step** (int) - The step size. Must be non-zero. Defaults to 1.

### Example
```dart
var slice = SliceSpec(0, 10, step: 2); // Represents a slice from index 0 up to (but not including) index 10, with a step of 2.
```

### Implementation Notes
Throws an `ArgumentError` if the provided `step` is zero.
```

--------------------------------

### MySQLConnection Constructor

Source: https://pub.dev/documentation/dartframe/latest/dartframe/MySQLConnection/MySQLConnection.html

Initializes a new MySQLConnection with a given connection string.

```APIDOC
## MySQLConnection(String _connectionString)

### Description
Constructs a new MySQLConnection instance.

### Parameters
#### Path Parameters
- **_connectionString** (String) - Required - The connection string to use for establishing the MySQL connection.
```

--------------------------------

### Slice.range(int start, int stop, {int step = 1})

Source: https://pub.dev/documentation/dartframe/latest/dartframe/Slice-class.html

Creates a slice specification to select a range of elements with an optional step. Equivalent to `[start:stop:step]`.

```APIDOC
## Slice.range(int start, int stop, {int step = 1})

### Description
Selects a range of elements from a collection, with an optional step.

### Method
static SliceSpec range(int start, int stop, {int step = 1})

### Parameters
#### Path Parameters
- **start** (int) - Required - The starting index (inclusive) for the slice.
- **stop** (int) - Required - The ending index (exclusive) for the slice.
- **step** (int) - Optional - The interval between selected elements. Defaults to 1.
```

--------------------------------

### Reading a Dataset in Chunks

Source: https://pub.dev/documentation/dartframe/latest/dartframe/Hdf5File/readDatasetChunked.html

Demonstrates how to open an HDF5 file and read its dataset in manageable chunks using a for-await-in loop. Useful for large datasets.

```dart
final file = await Hdf5File.open('large_data.h5');
await for (final chunk in file.readDatasetChunked('/data', chunkSize: 10000)) {
  // Process each chunk
  print('Processing ${chunk.length} elements');
  // ... do something with chunk
}
```

--------------------------------

### CompactLayout Constructor

Source: https://pub.dev/documentation/dartframe/latest/dartframe/CompactLayout-class.html

Initializes a new CompactLayout instance with the provided data.

```APIDOC
## CompactLayout

### Description
Initializes a new CompactLayout instance with the provided data.

### Parameters
#### Path Parameters
- **data** (List<int>) - Required - The list of integers representing the compact data.
```

--------------------------------

### Get Root Group

Source: https://pub.dev/documentation/dartframe/latest/dartframe/Hdf5File/root.html

Gets the root group of the HDF5 file. The root group contains all top-level datasets and groups in the file. You can access its children using the Group.children property.

```APIDOC
## Get Root Group

### Description
Gets the root group of the HDF5 file. The root group contains all top-level datasets and groups in the file. You can access its children using the Group.children property.

### Example
```dart
final file = await Hdf5File.open('data.h5');
print('Root children: ${file.root.children}');
```

### Implementation
```dart
Group get root => _rootGroup;
```
```

--------------------------------

### Implement DataFrame limit method

Source: https://pub.dev/documentation/dartframe/latest/dartframe/DataFrameFunctions/limit.html

This method returns a new DataFrame containing a specified number of rows, starting from a given index. It includes error handling for invalid start indices.

```dart
DataFrame limit(int limit, {int startIndex = 0}) {
  if (startIndex < 0 || startIndex >= _data.length) {
    throw ArgumentError('Invalid start index.');
  }

  final endIndex = startIndex + limit;
  final limitedData = _data.sublist(
      startIndex, endIndex < _data.length ? endIndex : _data.length);

  return DataFrame._(_columns, limitedData);
}
```

--------------------------------

### Example Usage of tryStack

Source: https://pub.dev/documentation/dartframe/latest/dartframe/DataFrameStacker/tryStack.html

Demonstrates how to use the tryStack method and check for compatibility. Use this when you need to stack DataFrames without risking an exception.

```dart
var frames = [df1, df2, df3];
var cube = DataFrameStacker.tryStack(frames);
if (cube != null) {
  print('Successfully created DataCube');
} else {
  print('DataFrames are incompatible');
}

```

--------------------------------

### connect method

Source: https://pub.dev/documentation/dartframe/latest/dartframe/PostgreSQLConnection/connect.html

Establishes a connection to a PostgreSQL database using a connection string. It parses the connection details, validates the scheme, and opens a connection using the provided endpoint and settings. Throws a DatabaseConnectionError if the connection string is empty, invalid, or if the connection fails.

```APIDOC
## connect()

### Description
Establishes a connection to a PostgreSQL database.

### Method Signature
Future<void> connect()

### Implementation Details
- Parses the connection string to extract host, port, username, password, and database.
- Validates that the connection string scheme is 'postgresql' or 'postgres'.
- Uses `pg.Connection.open` to establish the connection.
- Sets `pg.SslMode` to `disable`.
- Throws `DatabaseConnectionError` on failure.
```

--------------------------------

### Create SliceSpec Instance

Source: https://pub.dev/documentation/dartframe/latest/dartframe/SliceSpec/SliceSpec.html

Instantiate SliceSpec with start, stop, and an optional step. The step defaults to 1 if not provided. Use null for start or stop to indicate the beginning or end of the sequence, respectively.

```dart
var slice = SliceSpec(0, 10, step: 2);  // [0:10:2]

```

--------------------------------

### DCFReader Constructor

Source: https://pub.dev/documentation/dartframe/latest/dartframe/DCFReader/DCFReader.html

Initializes a new DCFReader instance with the specified file path.

```APIDOC
## DCFReader Constructor

### Description
Initializes a new DCFReader instance.

### Parameters
#### Path Parameters
- **_path** (String) - Required - The path to the DCF file.
```

--------------------------------

### Create Slice from Start Index

Source: https://pub.dev/documentation/dartframe/latest/dartframe/Slice/from.html

Use the `from()` static method to create a slice that begins at the specified start index and extends to the end of the sequence. This is useful for selecting a sub-sequence from a particular point onwards.

```dart
var slice = Slice.from(5);  // [5:]
```

```dart
static SliceSpec from(int start) => SliceSpec(start, null);
```

--------------------------------

### dtypeInfo

Source: https://pub.dev/documentation/dartframe/latest/dartframe/SeriesDType.html

Get the DType of this Series.

```APIDOC
## dtypeInfo

### Description
Get the DType of this Series.

### Returns
- dtypeInfo (DType) - The data type of the Series.
```
Tokens:
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