### Example Druid Query Output

Source: https://plywood.imply.io/index

This is an example of the JSON output from a basic Plywood query to Druid, showing aggregated metrics.

```json
[
  {
    "70": 70,
    "TotalAdded": 32553107,
    "Count": 113240
  }
]
```

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

### Querying Data with PlyQL

Source: https://plywood.imply.io/plyql

A basic example demonstrating how to query data from a table using PlyQL.

```plyql
QUANTILE(delta_hist WHERE cityName = "San Francisco", 0.95) as P95 
FROM wikipedia;
```

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

### Example Druid Query Output with Split

Source: https://plywood.imply.io/index

This is an example of the JSON output from a Plywood query to Druid that includes a split, showing aggregated data and a nested list of top pages.

```json
[
  {
    "TotalAdded": 32553107,
    "Count": 113240
  }
]
[
  {
    "TotalAdded": 97393743,
    "Count": 389319,
    "Pages": [
      {
        "Page": "Jeremy Corbyn",
        "Count": 314
      },
      {
        "Page": "User:Cyde/List of candidates for speedy deletion/Subpage",
        "Count": 255
      },
      {
        "Page": "Wikipedia:Administrators' noticeboard/Incidents",
        "Count": 228
      },
      {
        "Page": "Wikipedia:Vandalismusmeldung",
        "Count": 186
      },
      {
        "Page": "Total Drama Presents: The Ridonculous Race",
        "Count": 160
      },
      {
        "Page": "Wikipedia:Administrator intervention against vandalism",
        "Count": 145
      }
    ]
  }
]
```

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

### Create a Simple Plywood Query

Source: https://plywood.imply.io/index

Demonstrates creating a Plywood query by starting with an empty dataset, applying literal values, and creating expressions using string parsing and method chaining. The `compute()` method resolves the query.

```javascript
var ex0 = ply() // Create an empty singleton dataset literal [{}]
  // 1 is converted into a literal
  .apply("one", 1)

  // The string "$one + 1" is parsed into an expression
  .apply("two", "$one + 1")

  // The method chaining approach is used to make an expression
  .apply("four", $("two").multiply(2))
```

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

### Plywood Query Result Example

Source: https://plywood.imply.io/index

Illustrates the expected nested data structure output after computing a Plywood query.

```json
[
  {
    one: 1,
    two: 2,
    four: 4
  }
]
```

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

### Nested Queries in PlyQL

Source: https://plywood.imply.io/plyql

An advanced example showcasing nested queries in PlyQL, where datasets are treated as datatypes for nesting.

```plyql
plyql -h 192.168.60.100:8082 -i P1Y -q '
SELECT page as Page, 
COUNT() as cnt, 
(
  SELECT 
  SUM(added) as TotalAdded 
  GROUP BY TIME_BUCKET(__time, PT1H, "Etc/UTC") 
  LIMIT 3 -- only get the first 3 hours to keep this example output small
) as "ByTime" 
FROM wikipedia 
GROUP BY page 
ORDER BY cnt DESC 
LIMIT 5;
'
```

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

### Construct Basic Druid Query

Source: https://plywood.imply.io/index

Build a Plywood query to fetch data from Druid. This example filters by time and channel, calculates the total count and sum of 'added' attribute, and includes a constant value from the context.

```javascript
var ex = ply()
  // Define the external in scope with a filter on time and language
  .apply("wiki",
    $('wiki').filter($("time").in({
      start: new Date("2015-09-12T00:00:00Z"),
      end: new Date("2015-09-13T00:00:00Z")
    }).and($('channel').is('en')))
  )

  // Calculate count
  .apply('Count', $('wiki').count())

  // Calculate the sum of the `added` attribute
  .apply('TotalAdded', '$wiki.sum($added)');

  // Refer to the seventy defined in the context
  .apply('70', $('seventy'));
```

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

### Numeric Bucketing with NUMBER_BUCKET

Source: https://plywood.imply.io/plyql

Buckets numeric data into specified sizes with an offset. Buckets are inclusive of the start and exclusive of the end.

```plyql
NUMBER_BUCKET($revenue, 5, 1)
```

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

### Substring Extraction with SUBSTR

Source: https://plywood.imply.io/plyql

Extracts a substring of a specified length from a string, starting at a given position.

```plyql
SUBSTR(_str_, _pos_, _len_)
```

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

### Get String Length

Source: https://plywood.imply.io/expressions

Returns the number of characters in the string operand.

```javascript
var ex = $(\'str\').length();
ex.compute({ str: \'morning\' }).then(console.log); // => 7
```

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

### Show Tables with PlyQL

Source: https://plywood.imply.io/plyql

Use this command to list all available data sources in Druid. Specify the broker host and port using the -h option.

```bash
plyql -h 192.168.60.100:8082 -q 'SHOW TABLES'
```

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

### Extract Substring

Source: https://plywood.imply.io/expressions

Extracts a portion of a string operand based on a starting position and length.

```javascript
var ex = $(\'str\').substr(1, 5);
ex.compute({ str: \'Hello World\' }).then(console.log); // => \'ello \'
```

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

### Describe Data Source Schema with PlyQL

Source: https://plywood.imply.io/plyql

Use this command to view the column definitions and types for a specific Druid data source. Replace 'wikipedia' with your data source name.

```bash
plyql -h 192.168.60.100:8082 -q 'DESCRIBE wikipedia'
```

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

### Configure a Druid External

Source: https://plywood.imply.io/design-overview

Set up a Druid external for Plywood to connect to a Druid database. Requires specifying the engine, datasource, time attribute, and a requester.

```javascript
External.fromJS({
  engine: 'druid',         
  source: 'wikipedia',  // The datasource name in Druid
  timeAttribute: 'time',    // Druid's anonymous time attribute will be called 'time'

  requester: druidRequester // a thing that knows how to make Druid requests
})
```

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

### Define Sample Dataset

Source: https://plywood.imply.io/expressions

Defines a sample dataset using Dataset.fromJS for testing or demonstration purposes.

```javascript
var someDataset = Dataset.fromJS([
  { cut: \'Good\',  price: 400, time: new Date(\'2015-10-01T10:20:30Z\') }
  { cut: \'Good\',  price: 300, time: new Date(\'2015-10-02T10:20:30Z\') }
  { cut: \'Great\', price: 124, time: null }
  { cut: \'Wow\',   price: 160, time: new Date(\'2015-10-04T10:20:30Z\') }
  { cut: \'Wow\',   price: 100, time: new Date(\'2015-10-05T10:20:30Z\') }
]);
```

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

### Execute and Log Basic Query Results

Source: https://plywood.imply.io/index

Compute the Plywood query using the defined context and log the results to the console in a formatted JSON string. The '.done()' method ensures the query is executed.

```javascript
ex.compute(context).then(function(data) {
  // Log the data while converting it to a readable standard
  console.log(JSON.stringify(data.toJS(), null, 2));
}).done();
```

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

### Import Plywood and Core Functions

Source: https://plywood.imply.io/index

Import necessary functions from the Plywood library. `ply()` creates a dataset literal, and `$` creates a Reference Expression.

```javascript
var plywood = require('plywood');
var ply = plywood.ply;
var $ = plywood.$;
```

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

### Build a Plywood Expression

Source: https://plywood.imply.io/design-overview

Use this to construct data queries with Plywood's expression language. It supports operations like apply, split, sort, and limit.

```javascript
var ex = ply()
  .apply('Count', $('wiki').count())
  .apply('TotalAdded', '$wiki.sum($added)')
  .apply('Pages',
    $('wiki').split('$page', 'Page')
      .apply('Count', $('wiki').count())
      .sort('$Count', 'descending')
      .limit(6)
  );
```

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

### Configure Druid Requester

Source: https://plywood.imply.io/index

Initialize the Druid requester factory with the host address of your Druid instance. This object will handle communication with Druid.

```javascript
var druidRequester = druidRequesterFactory({
  host: '192.168.60.100:8082' // Where ever your Druid may be
});
```

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

### Multi-dimensional GROUP BY in PlyQL

Source: https://plywood.imply.io/plyql

Demonstrates multi-dimensional GROUP BY operations in PlyQL, useful for complex aggregations.

```plyql
plyql -h 192.168.60.100:8082 -i P1Y -q '
SELECT TIME_BUCKET(__time, PT1H, "Etc/UTC") as Hour, 
page as PageName, 
SUM(added) as TotalAdded 
FROM wikipedia 
GROUP BY 1, 2 
ORDER BY TotalAdded DESC 
LIMIT 3; 
'
```

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

### Representing a Dataset

Source: https://plywood.imply.io/datatypes

Use Dataset.fromJS to create a dataset, which is an abstract representation of a table or data source. Each datum is a collection of attributes.

```javascript
Dataset.fromJS([
  { x: 1, y: "USA" }
  { x: 2, y: "UK" }
])
```

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

### PLYQL String and Utility Functions

Source: https://plywood.imply.io/plyql

Functions for string manipulation, lookup, null handling, and custom transformations.

```APIDOC
## String and Utility Functions

### `SUBSTR(str, pos, len)`
Returns a substring of `str` starting at `pos` with length `len`.

### `CONCAT(str1, str2, ...)`
Concatenates one or more string arguments.

### `EXTRACT(str, regexp)`
Returns the first matching group from applying `regexp` to `str`.

### `LOOKUP(str, lookup-namespace)`
Returns the value for `str` within the specified `lookup-namespace`.

### `IFNULL(expr1, expr2)`
Returns `expr1` if it is not null, otherwise returns `expr2`.

### `FALLBACK(expr1, expr2)`
Synonym for `IFNULL(expr1, expr2)`.

### `OVERLAP(expr1, expr2)`
Checks if `expr1` and `expr2` overlap.

### `CUSTOM_TRANSFORM(expr1, custom_name)`
Applies a specified custom transformation to an expression.
```

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

### Define Plywood Execution Context

Source: https://plywood.imply.io/index

Set up an execution context map for Plywood queries. This context allows you to reference Plywood External objects (like 'wikiDataset') and other values (like 'seventy') by name within your queries.

```javascript
var context = {
  wiki: wikiDataset,
  seventy: 70
};
```

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

### Construct Druid Query with Split and Sort

Source: https://plywood.imply.io/index

Create a more complex Plywood query that includes a split on the 'page' attribute, calculates counts per page, and limits the results to the top 6 pages sorted by count.

```javascript
var ex = ply()
  .apply("wiki",
    $('wiki').filter($("time").in({
      start: new Date("2015-09-12T00:00:00Z"),
      end: new Date("2015-09-13T00:00:00Z")
    }))
  )
  .apply('Count', $('wiki').count())
  .apply('TotalAdded', '$wiki.sum($added)')
  .apply('Pages',
    $('wiki').split('$page', 'Page')
      .apply('Count', $('wiki').count())
      .sort('$Count', 'descending')
      .limit(6)
  );
```

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

### Time Bucketing with PlyQL

Source: https://plywood.imply.io/plyql

This query uses the TIME_BUCKET function to aggregate data into 6-hour intervals (PT6H) and calculates the sum of the 'added' column for each bucket. The results include the time range for each bucket.

```bash
plyql -h 192.168.60.100:8082 -i P1Y -q '
SELECT SUM(added) as TotalAdded 
FROM wikipedia 
GROUP BY TIME_BUCKET(__time, PT6H, "Etc/UTC");
'
```

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

### Exponentiation with POW and POWER

Source: https://plywood.imply.io/plyql

Calculates the value of the first expression raised to the power of the second expression. POW and POWER are synonyms.

```plyql
POW(_expr1_, _expr2_)
```

```plyql
POWER(_expr1_, _expr2_)
```

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

### Creating Time Ranges with TIME_RANGE

Source: https://plywood.imply.io/plyql

Creates a time range from a given time point and a point shifted by a specified duration and step in a given timezone. Supports negative steps.

```plyql
TIME_RANGE(time, 'P1D', -2, 'America/Los_Angeles')
```

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

### Import Druid Dependencies

Source: https://plywood.imply.io/index

Import necessary modules for Plywood and Druid integration. 'External' is the Plywood class for external data sources, and 'druidRequesterFactory' is specific to Druid.

```javascript
var External = plywood.External;
var druidRequesterFactory = require('plywood-druid-requester').druidRequesterFactory;
```

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

### Lookup Values with LOOKUP

Source: https://plywood.imply.io/plyql

Retrieves a value from a specified lookup namespace using a given string key.

```plyql
LOOKUP(_str_, _lookup-namespace_)
```

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

### select

Source: https://plywood.imply.io/expressions

Selects only the provided attributes from the dataset.

```APIDOC
## select(...attributes: string[])

### Description
Select only the provided attributes in the dataset.

### Parameters
#### Path Parameters
- **attributes** (string[]) - Required - A list of attribute names to select.

### Request Example
```javascript
var ex = $('data').select('cut', 'time');
ex.compute({ data: someDataset }).then(console.log);
```

### Response
#### Success Response (200)
- **Dataset** - The dataset with only the selected attributes.

#### Response Example
```javascript
Dataset.fromJS([
  { cut: 'Good',  time: new Date('2015-10-01T10:20:30Z') },
  { cut: 'Good',  time: new Date('2015-10-02T10:20:30Z') },
  { cut: 'Great', time: null }
])
```
```

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

### Add Operands

Source: https://plywood.imply.io/expressions

Use the add() method to sum the operand with the provided arguments. This is equivalent to parsing `operand + arguments`.

```javascript
var ex = $(\'x\').add('$y', 1);
ex.compute({ x: 10, y: 2 }).then(console.log); // => 13
```

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

### Define Druid External Data Source

Source: https://plywood.imply.io/index

Create an 'External' Plywood object representing a Druid datasource. Specify the engine, source name, time attribute, and any Druid-specific context.

```javascript
var wikiDataset = External.fromJS({
  engine: 'druid',
  source: 'wikipedia',  // The datasource name in Druid
  timeAttribute: 'time',  // Druid's anonymous time attribute will be called 'time',
  context: {
    timeout: 10000 // The Druid context
  }
}, druidRequester);
```

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

### PLYQL Operators

Source: https://plywood.imply.io/plyql

A comprehensive list of operators supported in PLYQL for various comparisons, logical operations, and pattern matching.

```APIDOC
## PLYQL Operators

### Arithmetic Operators
- `+`: Addition operator
- `-`: Minus operator / Unary negation
- `*`: Multiplication operator
- `/`: Division operator

### Comparison Operators
- `=, IS`: Equal operator
- `!=, <>`: Not equal operator
- `>=`: Greater than or equal operator
- `>`: Greater than operator
- `<=`: Less than or equal operator
- `<`: Less than operator

### Range Operators
- `BETWEEN ... AND ...`: Checks if a value is within a range.
- `NOT BETWEEN ... AND ...`: Checks if a value is not within a range.

### Pattern Matching Operators
- `LIKE, CONTAINS`: Simple pattern matching.
- `NOT LIKE, CONTAINS`: Negation of simple pattern matching.
- `REGEXP`: Pattern matching using regular expressions.
- `NOT REGEXP`: Negation of REGEXP.

### Logical Operators
- `NOT, !`: Negates a value.
- `AND`: Logical AND.
- `OR`: Logical OR.
```

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

### Time Bucketing with TIME_BUCKET

Source: https://plywood.imply.io/plyql

Buckets time data into specified durations within a given timezone. Useful for time-series analysis.

```plyql
TIME_BUCKET(time, 'P1D', 'America/Los_Angeles')
```

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

### Flooring Time with TIME_FLOOR

Source: https://plywood.imply.io/plyql

Floors time data to the nearest specified duration within a given timezone. Useful for aligning time data to specific intervals.

```plyql
TIME_FLOOR(time, 'P1D', 'America/Los_Angeles')
```

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

### Handling Null Values with IFNULL and FALLBACK

Source: https://plywood.imply.io/plyql

Provides a fallback expression if the primary expression evaluates to null. IFNULL and FALLBACK are synonyms.

```plyql
IFNULL(_expr1_, _expr2_)
```

```plyql
FALLBACK(_expr1_, _expr2_)
```

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

### apply

Source: https://plywood.imply.io/expressions

Applies a given expression to each row of the dataset and saves the result in a new field.

```APIDOC
## _operand_.**apply**(name: string, ex: any)

### Description
Apply the given expression to every datum in the dataset saving the result as `name`.

### Parameters
#### Path Parameters
- **name** (string) - Required - The name of the new field to store the result.
- **ex** (any) - Required - The expression to apply to each datum.

### Request Example
```javascript
var someDataset = Dataset.fromJS([
  { cut: 'Good',  price: 400, time: new Date('2015-10-01T10:20:30Z') },
  { cut: 'Good',  price: 300, time: new Date('2015-10-02T10:20:30Z') },
  { cut: 'Great', price: 124, time: null },
  { cut: 'Wow',   price: 160, time: new Date('2015-10-04T10:20:30Z') },
  { cut: 'Wow',   price: 100, time: new Date('2015-10-05T10:20:30Z') }
]);

var ex = $("data").apply('DoublePrice', '$price * 2');
ex.compute({ data: someDataset }).then(console.log);
// =>
// Dataset.fromJS([
//   { cut: 'Good',  price: 400, DoublePrice: 800, time: new Date('2015-10-01T10:20:30Z') },
//   { cut: 'Good',  price: 300, DoublePrice: 600, time: new Date('2015-10-02T10:20:30Z') },
//   { cut: 'Great', price: 124, DoublePrice: 248, time: null },
//   { cut: 'Wow',   price: 160, DoublePrice: 320, time: new Date('2015-10-04T10:20:30Z') },
//   { cut: 'Wow',   price: 100, DoublePrice: 200, time: new Date('2015-10-05T10:20:30Z') }
// ])
```
```

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

### Group and Order Results with PlyQL

Source: https://plywood.imply.io/plyql

This query groups results by the 'page' column, counts occurrences, and orders them by count in descending order, limiting to the top 5. A time filter is required to prevent computationally expensive queries.

```bash
plyql -h 192.168.60.100:8082 -q '
SELECT page as pg, 
COUNT() as cnt 
FROM wikipedia 
GROUP BY page 
ORDER BY cnt DESC 
LIMIT 5;
'
```

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

### String Concatenation with CONCAT

Source: https://plywood.imply.io/plyql

Concatenates two or more strings together. Can accept a variable number of string arguments.

```plyql
CONCAT(_str1_, _str2_, ...)
```

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

### Group and Order with Interval Filter using PlyQL

Source: https://plywood.imply.io/plyql

This command uses the --interval (-i) option to automatically filter data for the last year (P1Y). This simplifies queries where you need recent data without specifying exact timestamps.

```bash
plyql -h 192.168.60.100:8082 -i P1Y -q '
SELECT page as pg, 
COUNT() as cnt 
FROM wikipedia 
GROUP BY page 
ORDER BY cnt DESC 
LIMIT 5;
'
```

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

### Group and Order with Time Filter using PlyQL

Source: https://plywood.imply.io/plyql

This query is similar to the previous one but includes a specific time range filter. This is crucial for performance on large datasets. The time filter ensures that only data within the specified range is considered.

```bash
plyql -h 192.168.60.100:8082 -q '
SELECT page as pg, 
COUNT() as cnt 
FROM wikipedia 
WHERE "2015-09-12T00:00:00" <= __time AND __time < "2015-09-13T00:00:00"
GROUP BY page 
ORDER BY cnt DESC 
LIMIT 5;
'
```

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

### lookup

Source: https://plywood.imply.io/expressions

Performs a lookup within a specified namespace.

```APIDOC
## lookup

### Description
Performs a lookup within the specified namespace.

### Method
operand.lookup(lookup: string)

```

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

### Minimum Value with MIN

Source: https://plywood.imply.io/plyql

Finds the minimum value among all values for a given expression.

```plyql
MIN(_expr_)
```

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

### PLYQL Numeric and Time Functions

Source: https://plywood.imply.io/plyql

Functions for bucketing numeric data, and manipulating time-based data including bucketing, extracting parts, flooring, shifting, and creating ranges.

```APIDOC
## Numeric and Time Functions

### `NUMBER_BUCKET(operand, size, offset)`
Buckets numeric data into buckets of a specified `size` with a given `offset`. Buckets are open-closed (start <= x < end).

Example: `NUMBER_BUCKET($revenue, 5, 1)`

### `TIME_BUCKET(operand, duration, timezone)`
Buckets time data into buckets of a specified `duration` in the given `timezone`.

Example: `TIME_BUCKET(time, 'P1D', 'America/Los_Angeles')`

### `TIME_PART(operand, part, timezone)`
Extracts specific parts of a time value based on repeating buckets in the given `timezone`.

Possible `part` values include:
  - `SECOND_OF_MINUTE`, `SECOND_OF_HOUR`, `SECOND_OF_DAY`, `SECOND_OF_WEEK`, `SECOND_OF_MONTH`, `SECOND_OF_YEAR`
  - `MINUTE_OF_HOUR`, `MINUTE_OF_DAY`, `MINUTE_OF_WEEK`, `MINUTE_OF_MONTH`, `MINUTE_OF_YEAR`
  - `HOUR_OF_DAY`, `HOUR_OF_WEEK`, `HOUR_OF_MONTH`, `HOUR_OF_YEAR`
  - `DAY_OF_WEEK`, `DAY_OF_MONTH`, `DAY_OF_YEAR`
  - `WEEK_OF_MONTH`, `WEEK_OF_YEAR`
  - `MONTH_OF_YEAR`
  - `YEAR`

Example: `TIME_PART(time, 'DAY_OF_YEAR', 'America/Los_Angeles')`

### `TIME_FLOOR(operand, duration, timezone)`
Floors a time value to the nearest `duration` in the given `timezone`.

Example: `TIME_FLOOR(time, 'P1D', 'America/Los_Angeles')`

### `TIME_SHIFT(operand, duration, step, timezone)`
Shifts a time value forwards by `duration` * `step` in the given `timezone`. `step` can be negative.

Example: `TIME_SHIFT(time, 'P1D', -2, 'America/Los_Angeles')`

### `TIME_RANGE(operand, duration, step, timezone)`
Creates a range from a time value and a point `duration` * `step` away in the given `timezone`. `step` can be negative.

Example: `TIME_RANGE(time, 'P1D', -2, 'America/Los_Angeles')`
```

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

### Power Operation

Source: https://plywood.imply.io/expressions

Use the power() method to raise the operand to a specified power. This is equivalent to parsing `operand ^ power`.

```javascript
var ex = $(\'x\').power(0.5);
ex.compute({ x: 4 }).then(console.log); // => 2
```

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

### Split Dataset by Category

Source: https://plywood.imply.io/expressions

Use `split` to divide a dataset into multiple subsets based on the unique values of a specified column. Each subset is named.

```javascript
var someDataset = Dataset.fromJS([
  { cut: 'Good',  price: 400, time: new Date('2015-10-01T10:20:30Z') },
  { cut: 'Good',  price: 300, time: new Date('2015-10-02T10:20:30Z') },
  { cut: 'Great', price: 124, time: null },
  { cut: 'Wow',   price: 160, time: new Date('2015-10-04T10:20:30Z') },
  { cut: 'Wow',   price: 100, time: new Date('2015-10-05T10:20:30Z') }
]);

var ex = $(\'data\').split('$cut', 'Cut');
ex.compute({ data: someDataset }).then(console.log);
// =>
Dataset.fromJS([
  {
    Cut: 'Good',
    data: [
      { cut: 'Good',  price: 400, time: new Date('2015-10-01T10:20:30Z') },
      { cut: 'Good',  price: 300, time: new Date('2015-10-02T10:20:30Z') }
    ]
  },
  {
    Cut: 'Great',
    data: [
      { cut: 'Great', price: 124, time: null }
    ]
  },
  {
    Cut: 'Wow',
    data: [
      { cut: 'Wow',   price: 160, time: new Date('2015-10-04T10:20:30Z') },
      { cut: 'Wow',   price: 100, time: new Date('2015-10-05T10:20:30Z') }
    ]
  }
])
```

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

### Representing a Set of Strings

Source: https://plywood.imply.io/datatypes

Use Set.fromJS to create a set of distinct string elements. The elements within a set must all have the same type.

```javascript
Set.fromJS(['USA', 'UK', 'Japan'])
```

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

### Time Bucketing

Source: https://plywood.imply.io/expressions

Buckets a time operand to the nearest duration within a specified timezone, creating a TimeRange.

```javascript
var ex = $(\'time\').timeBucket(\'P1D\');
```

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

### Calculate Quantile of Expression

Source: https://plywood.imply.io/expressions

Computes a specified quantile for a given expression in the dataset. The 0.5 quantile is the median. Does not require sorted data.

```javascript
var ex = $(\'data\').quantile($(\'price\'), 0.95);
ex.compute({ data: someDataset }).then(console.log); // => 167.343
```

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

### Representing a Time Range

Source: https://plywood.imply.io/datatypes

Use TimeRange.fromJS to create a time range object. This is often the result of bucketing.

```javascript
TimeRange.fromJS({ start: new Date('2015-02-24T18:00:00'), end: new Date('2015-02-24T19:00:00') })
```

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

### Reciprocate Operand

Source: https://plywood.imply.io/expressions

Use the reciprocate() method to calculate the reciprocal of the operand. This is equivalent to parsing `1 / operand`.

```javascript
var ex = $(\'x\').reciprocate();
ex.compute({ x: 10 }).then(console.log); // => 0.1
```

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

### Apply Transformation to Dataset Column

Source: https://plywood.imply.io/expressions

Use `apply` to create a new column in the dataset by applying an expression to each row. This is useful for feature engineering.

```javascript
var someDataset = Dataset.fromJS([
  { cut: 'Good',  price: 400, time: new Date('2015-10-01T10:20:30Z') },
  { cut: 'Good',  price: 300, time: new Date('2015-10-02T10:20:30Z') },
  { cut: 'Great', price: 124, time: null },
  { cut: 'Wow',   price: 160, time: new Date('2015-10-04T10:20:30Z') },
  { cut: 'Wow',   price: 100, time: new Date('2015-10-05T10:20:30Z') }
]);

var ex = $(\'data\').apply('DoublePrice', '$price * 2');
ex.compute({ data: someDataset }).then(console.log);
// =>
Dataset.fromJS([
  { cut: 'Good',  price: 400, DoublePrice: 800, time: new Date('2015-10-01T10:20:30Z') },
  { cut: 'Good',  price: 300, DoublePrice: 600, time: new Date('2015-10-02T10:20:30Z') },
  { cut: 'Great', price: 124, DoublePrice: 248, time: null },
  { cut: 'Wow',   price: 160, DoublePrice: 320, time: new Date('2015-10-04T10:20:30Z') },
  { cut: 'Wow',   price: 100, DoublePrice: 200, time: new Date('2015-10-05T10:20:30Z') }
])
```

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

### Predefined Literal Expressions

Source: https://plywood.imply.io/expressions

Plywood provides static members on the Expression class for common literal values like NULL, ZERO, ONE, FALSE, TRUE, and EMPTY_STRING.

```javascript
Expression.NULL.equals(r(null));

Expression.ZERO.equals(r(0));

Expression.ONE.equals(r(1));

Expression.FALSE.equals(r(false));

Expression.TRUE.equals(r(true));

Expression.EMPTY_STRING.equals(r(''));
```

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

### timeBucket

Source: https://plywood.imply.io/expressions

Buckets a time operand to the nearest duration within a specified timezone.

```APIDOC
## timeBucket

### Description
Buckets the operand time to the nearest `duration` within the given `timezone`. Creates a TimeRange of size `duration`. 

### Method
operand.timeBucket(duration: any, timezone?: string)

### Example
```javascript
var ex = $(\'time\').timeBucket(\'P1D\');
```
```

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

### numberBucket

Source: https://plywood.imply.io/expressions

Buckets a numeric operand into defined ranges based on size and offset.

```APIDOC
## numberBucket

### Description
Buckets the numeric operand to buckets defined by the `size` and `offset`.

### Method
operand.numberBucket(size: number, offset: number = 0)

### Example
```javascript
var ex = $(\'x\').numberBucket(5);
ex.compute({ x: 7 }).then(console.log); // => [5, 10)
```
```

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

### Divide Operands

Source: https://plywood.imply.io/expressions

Use the divide() method to divide the operand by the provided arguments. This is equivalent to parsing `operand / arguments`.

```javascript
var ex = $(\'x\').divide('$y');
ex.compute({ x: 10, y: 2 }).then(console.log); // => 5
```

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

### Maximum Value with MAX

Source: https://plywood.imply.io/plyql

Finds the maximum value among all values for a given expression.

```plyql
MAX(_expr_)
```

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

### match

Source: https://plywood.imply.io/expressions

Checks if the operand matches the provided regular expression string.

```APIDOC
## match

### Description
Checks whether the operand matches the given RegExp that is provided as a string.

### Method
operand.match(re: string)

### Example
```javascript
var ex = $(\'str\').match(\'^Hell.*d\


);
ex.compute({ str: \'Hello World\' }).then(console.log); // => true
```
```

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

### and

Source: https://plywood.imply.io/expressions

Performs a boolean AND operation between the operand and other expressions.

```APIDOC
## and

### Description
Performs a boolean AND operation on the operand and the given expressions. Writing `$(\'x\').and($(\'y\'))` is the same as parsing `$x and $y`

### Method
operand.and(...exs: any[])

### Example
```javascript
var ex = $(\'x\').and($(\'y\'));
ex.compute({ x: true, y: false }).then(console.log); // => false
```
```

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

### Row Count with COUNT

Source: https://plywood.imply.io/plyql

Counts the number of rows. If an expression is provided, it counts rows where the expression is not null.

```plyql
COUNT(*)
```

```plyql
COUNT(_expr?_)
```

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

### PLYQL Aggregation Functions

Source: https://plywood.imply.io/plyql

Functions for performing aggregations such as count, sum, minimum, maximum, average, and quantile.

```APIDOC
## Aggregation Functions

### `COUNT(expr?)`
Returns the count of rows. If an expression is provided, returns the count of rows where the expression is not null. `COUNT(*)` counts all rows.

### `COUNT(DISTINCT expr), COUNT_DISTINCT(expr)`
Returns the count of distinct values for the given expression.

### `SUM(expr)`
Returns the sum of all values for the given expression.

### `MIN(expr)`
Returns the minimum value for the given expression.

### `MAX(expr)`
Returns the maximum value for the given expression.

### `AVG(expr)`
Returns the average of all values for the given expression.

### `QUANTILE(expr, quantile)`
Returns the upper `quantile` of all values for the given expression.
```

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

### Query Maximum Time with PlyQL

Source: https://plywood.imply.io/plyql

This query retrieves the timestamp of the latest event in the specified data source. It uses the MAX aggregation function.

```bash
plyql -h 192.168.60.100:8082 -q 'SELECT MAX(__time) AS maxTime FROM wikipedia'
```

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

### Summation with SUM

Source: https://plywood.imply.io/plyql

Calculates the sum of all values for a given numeric expression.

```plyql
SUM(_expr_)
```

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

### Applying Custom Transformations with CUSTOM_TRANSFORM

Source: https://plywood.imply.io/plyql

Applies a user-defined custom transformation to an expression.

```plyql
CUSTOM_TRANSFORM(_expr1_, _custom_name_)
```

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

### length

Source: https://plywood.imply.io/expressions

Returns the length of the string operand.

```APIDOC
## length

### Description
Returns the length of the string

### Method
operand.length()

### Example
```javascript
var ex = $(\'str\').length();
ex.compute({ str: \'morning\' }).then(console.log); // => 7
```
```

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

### Create Reference Expression

Source: https://plywood.imply.io/expressions

Use $('name') to create an expression that references a value by its name. This is equivalent to parsing `$name`.

```javascript
var ex = $(\'x\');
ex.compute({ x: 10 }).then(console.log); // => 10
```

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

### PLYQL Mathematical Functions

Source: https://plywood.imply.io/plyql

Mathematical functions for calculating absolute values, powers, square roots, and exponential values.

```APIDOC
## Mathematical Functions

### `ABS(expr)`
Returns the absolute value of `expr`.

### `POW(expr1, expr2)`
Returns `expr1` raised to the power of `expr2`.

### `POWER(expr1, expr2)`
Synonym for `POW(expr1, expr2)`.

### `SQRT(expr)`
Returns the square root of `expr`.

### `EXP(expr)`
Returns e (base of natural logarithms) raised to the power of `expr`.
```

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

### Representing a Number Range

Source: https://plywood.imply.io/datatypes

Use NumberRange.fromJS to create a number range object. This is often the result of bucketing.

```javascript
NumberRange.fromJS({ start: 4, end: 7.5 })
```

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

### fallback

Source: https://plywood.imply.io/expressions

Provides a fallback value if the operand is null.

```APIDOC
## fallback

### Description
Returns value of given expression if operand is null. Writing `$(\'str\').fallback(r(\'hello\'))` is the same as parsing `$str === null ? \'hello\' : $str`

### Method
operand.fallback(...exs: typeof operand)

### Example
```javascript
var ex = $(\'str\').extract("([0-9]+\\.[0-9]+\\.[0-9]+)").fallback(\'missing\');
ex.compute({ str: \'kafka-0.7.2\' }).then(console.log); // => \'0.7.2\'
ex.compute({ str: \'Web 2.0\' }).then(console.log); // => \'missing\'
```
```

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

### cardinality

Source: https://plywood.imply.io/expressions

Returns the number of elements in a set.

```APIDOC
## cardinality

### Description
Returns the cardinality of the set

### Method
operand.cardinality()

### Example
```javascript
var ex = $(\'colors\').length();
ex.compute({ colors: [\'red\', \'orange\', \'green\', \'blue\'] }).then(console.log); // => 4
```
```

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

### Limit Dataset Size

Source: https://plywood.imply.io/expressions

Limits the number of records in a dataset to a specified positive integer. Useful for pagination or sampling.

```javascript
var ex = $(\'data\').limit(3);
ex.compute({ data: someDataset }).then(console.log);
```

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

### collect

Source: https://plywood.imply.io/expressions

Computes the set of values in a specified column.

```APIDOC
## collect(ex: any)

### Description
Computes the set of values in a certain column.

### Parameters
#### Path Parameters
- **ex** (any) - Required - The expression representing the column to collect values from.

### Request Example
```javascript
var ex = $('data').collect($('cut'));
ex.compute({ data: someDataset }).then(console.log); // => Set('Good', 'Great', 'Wow')
```

### Response
#### Success Response (200)
- **Set** - A set containing the distinct values from the specified column.

```

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

### timeRange

Source: https://plywood.imply.io/expressions

Constructs a range with the operand time as one end point and the other endpoint determined by shifting the provided time by `duration` _`step` within the given `timezone`. Creates a TimeRange of size `duration` _ `step`.

```APIDOC
## _operand_.**timeRange**(duration: any, step: number, timezone?: string)

### Description
Constructs a range with the operand time as one end point and the other endpoint determined by shifting the provided time by `duration` _`step` within the given `timezone`. Creates a TimeRange of size `duration` _ `step`.

### Parameters
#### Path Parameters
- **duration** (any) - Required - The duration to define the range size.
- **step** (number) - Required - The multiplier for the duration to determine the range size.
- **timezone** (string) - Optional - The timezone to use for the range calculation.

### Request Example
```javascript
var ex = $("time").timeRange("P1D", -2);
```
```

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

### String Match with RegExp

Source: https://plywood.imply.io/expressions

Checks if a string operand matches a given regular expression provided as a string.

```javascript
var ex = $(\'str\').match(\'^Hell.*d\n\n\n\n\');
ex.compute({ str: \'Hello World\' }).then(console.log); // => true
```

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

### Negate Operand

Source: https://plywood.imply.io/expressions

Use the negate() method to apply a negative sign to the operand. This is equivalent to parsing `-operand`.

```javascript
var ex = $(\'x\').negate();
ex.compute({ x: 10 }).then(console.log); // => -10
```

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

### Time Part Extraction with PlyQL

Source: https://plywood.imply.io/plyql

This query extracts the hour of the day from the __time column using TIME_PART and calculates the total 'added' for each hour. The results are ordered by TotalAdded in descending order, limited to the top 3 hours.

```bash
plyql -h 192.168.60.100:8082 -i P1Y -q '
SELECT TIME_PART(__time, HOUR_OF_DAY, "Etc/UTC") as HourOfDay, 
SUM(added) as TotalAdded 
FROM wikipedia 
GROUP BY 1 
ORDER BY TotalAdded DESC LIMIT 3;
'
```

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

### Exponential Function with EXP

Source: https://plywood.imply.io/plyql

Calculates the value of 'e' (Euler's number) raised to the power of the given expression.

```plyql
EXP(_expr_)
```

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

### Average Value with AVG

Source: https://plywood.imply.io/plyql

Calculates the average of all values for a given numeric expression.

```plyql
AVG(_expr_)
```

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

### Extracting Groups with EXTRACT

Source: https://plywood.imply.io/plyql

Extracts the first matching group from a string based on a regular expression.

```plyql
EXTRACT(_str_, _regexp_)
```

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

### Multiply Operands

Source: https://plywood.imply.io/expressions

Use the multiply() method to multiply the operand by the provided arguments. This is equivalent to parsing `operand * arguments`.

```javascript
var ex = $(\'x\').multiply('$y', 3);
ex.compute({ x: 10, y: 2 }).then(console.log); // => 60
```

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

### timeFloor

Source: https://plywood.imply.io/expressions

Floors the operand time to the nearest `duration` within the given `timezone`.

```APIDOC
## _operand_.**timeFloor**(duration: any, timezone?: string)

### Description
Floors the operand time to the nearest `duration` within the given `timezone`.

### Parameters
#### Path Parameters
- **duration** (any) - Required - The duration to floor the time to.
- **timezone** (string) - Optional - The timezone to use for flooring.

### Request Example
```javascript
var ex = $("time").timeFloor("P1D");
```
```

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

### indexOf

Source: https://plywood.imply.io/expressions

Returns the 0-based index of a substring within the operand.

```APIDOC
## indexOf

### Description
Returns the 0 based index of the substring in the operand. 

### Method
operand.indexOf(substr: string)

### Example
```javascript
var ex = r(\'hello\').indexOf(\'e\');
ex.compute().then(console.log); // => 1
```
```

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

### Construct Time Range

Source: https://plywood.imply.io/expressions

Use `timeRange` to create a time range where one endpoint is the operand time and the other is determined by shifting it. The range size is duration * step.

```javascript
var ex = $(\'time\').timeRange(\'P1D\', -2);
```

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

### Shifting Time with TIME_SHIFT

Source: https://plywood.imply.io/plyql

Shifts time data forwards or backwards by a specified duration and step in a given timezone. Supports negative steps for backward shifting.

```plyql
TIME_SHIFT(time, 'P1D', -2, 'America/Los_Angeles')
```

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

### min

Source: https://plywood.imply.io/expressions

Computes the minimum value of the given expression in the operand dataset.

```APIDOC
## min(ex: any)

### Description
Computes the min of the given expression in the operand dataset.

### Parameters
#### Path Parameters
- **ex** (any) - Required - The expression to find the minimum of.

### Request Example
```javascript
var ex = $('data').min($('price'));
ex.compute({ data: someDataset }).then(console.log); // => 100
```

### Response
#### Success Response (200)
- **number** - The minimum value of the expression.

```

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

### Create Literal Value Expression

Source: https://plywood.imply.io/expressions

Use r(value) to create an expression that represents a literal value. This is useful for constants or initial values.

```javascript
var ex = r('Hello World');
ex.compute().then(console.log); // => 'Hello World'
```

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

### split

Source: https://plywood.imply.io/expressions

Splits a dataset into multiple datasets based on the values of a specified expression.

```APIDOC
## _operand_.**split**(splits: any, name?: string, dataName?: string)

### Description
Split the data based on the given expression.

### Parameters
#### Path Parameters
- **splits** (any) - Required - The expression to split the data by.
- **name** (string) - Optional - The name of the new field that will contain the split value.
- **dataName** (string) - Optional - The name of the field that will contain the split data.

### Request Example
```javascript
var someDataset = Dataset.fromJS([
  { cut: 'Good',  price: 400, time: new Date('2015-10-01T10:20:30Z') },
  { cut: 'Good',  price: 300, time: new Date('2015-10-02T10:20:30Z') },
  { cut: 'Great', price: 124, time: null },
  { cut: 'Wow',   price: 160, time: new Date('2015-10-04T10:20:30Z') },
  { cut: 'Wow',   price: 100, time: new Date('2015-10-05T10:20:30Z') }
]);

var ex = $("data").split("$cut", "Cut");
ex.compute({ data: someDataset }).then(console.log);
// =>
// Dataset.fromJS([
//   {
//     Cut: 'Good',
//     data: [
//       { cut: 'Good',  price: 400, time: new Date('2015-10-01T10:20:30Z') },
//       { cut: 'Good',  price: 300, time: new Date('2015-10-02T10:20:30Z') }
//     ]
//   },
//   {
//     Cut: 'Great',
//     data: [
//       { cut: 'Great', price: 124, time: null }
//     ]
//   },
//   {
//     Cut: 'Wow',
//     data: [
//       { cut: 'Wow',   price: 160, time: new Date('2015-10-04T10:20:30Z') },
//       { cut: 'Wow',   price: 100, time: new Date('2015-10-05T10:20:30Z') }
//     ]
//   }
// ])
```
```

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

### Select Specific Attributes

Source: https://plywood.imply.io/expressions

Filters the dataset to include only the specified attributes. Useful for reducing data size or focusing on relevant fields.

```javascript
var ex = $(\'data\').select(\'cut\', \'time\');
ex.compute({ data: someDataset }).then(console.log);
```

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

### Subtract Operands

Source: https://plywood.imply.io/expressions

Use the subtract() method to subtract the provided arguments from the operand. This is equivalent to parsing `operand - arguments`.

```javascript
var ex = $(\'x\').subtract('$y', 1);
ex.compute({ x: 10, y: 2 }).then(console.log); // => 7
```

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

### or

Source: https://plywood.imply.io/expressions

Performs a boolean OR operation between the operand and other expressions.

```APIDOC
## or

### Description
Performs a boolean OR operation on the operand and the given expressions. Writing `$(\'x\').or($(\'y\'))` is the same as parsing `$x or $y`

### Method
operand.or(...exs: any[])

### Example
```javascript
var ex = $(\'x\').or($(\'y\'));
ex.compute({ x: true, y: false }).then(console.log); // => true
```
```