### sf_mline usage with matrix input

Source: https://github.com/dcooley/sfheaders/blob/master/docs/reference/sf_mline.html

Example demonstrating the use of sf_mline with a simple matrix input.

```APIDOC
## Example: Matrix Input

```R
m <- cbind(x = 0, y = 0, multilinestring_id = c(1, 1, 1), linestring_id = 1)
sf_mline( m )
```

### Output

```
  multilinestring_id         geometry
1                  1 0, 0, 0, 0, 0, 0
```
```

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

### sf_mline usage with data frame input

Source: https://github.com/dcooley/sfheaders/blob/master/docs/reference/sf_mline.html

Example demonstrating the use of sf_mline with a data frame input, including x, y, z, and m coordinates.

```APIDOC
## Example: Data Frame Input

```R
df <- data.frame(
  multilinestring_id = c(1,1,1,1,1,1,1,1,2,2,2,2,2)
  ,    linestring_id = c(1,1,1,2,2,3,3,3,1,1,1,2,2)
  , x = rnorm(13)
  , y = rnorm(13)
  , z = rnorm(13)
  , m = rnorm(13)
)

sf_mline( obj = df)
```

### Output

```
  multilinestring_id
1                  1
2                  2
                                                                                                                                                                                                                                                                                                                                                                                                          geometry
```
```

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

### Calculate bounding box for linestrings

Source: https://github.com/dcooley/sfheaders/blob/master/docs/reference/sf_boxes.html

Demonstrates how to use sf_boxes to get the bounding box of sf linestring objects. Requires the sfheaders package and a data frame with coordinates.

```R
df <- data.frame(
 id1 = c(1,1,1,1,1,1,1,1,2,2,2,2)
 , id2 = c(1,1,1,1,2,2,2,2,1,1,1,1)
 , x = c(0,0,1,1,1,1,2,2,3,4,4,3)
 , y = c(0,1,1,0,1,2,2,1,3,3,4,4)
)

sf_line <- sfheaders::sf_linestring(
 obj = df
 , x = "x"
 , y = "y"
 , linestring_id = "id1"
)

sf_boxes( sf_line )

```

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

### Create MultiLineString with X and Y

Source: https://github.com/dcooley/sfheaders/blob/master/docs/reference/sf_multilinestring.html

This example demonstrates creating a MultiLineString using only x and y coordinate columns. The 'obj' parameter should be your data frame.

```r
sf_multilinestring( obj = df, x = 3, y = 4)
```

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

### Create Polygon with X and Y Coordinates

Source: https://github.com/dcooley/sfheaders/blob/master/docs/reference/sf_polygon.html

This example demonstrates creating a polygon using only x and y coordinates from a data frame. Specify the 'obj' and the 'x' and 'y' column names.

```r
sf_polygon( obj = df, x = 2, y = 3)
```

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

### Create MULTIPOLYGON with polygon_id and linestring_id

Source: https://github.com/dcooley/sfheaders/blob/master/docs/reference/sfc_multipolygon.html

This example demonstrates creating a MULTIPOLYGON sfc object using both polygon_id and linestring_id to define the structure. The output shows the nested structure of the MULTIPOLYGON.

```R
sfc_multipolygon( df, x = "x", y = "y", polygon_id = "id1", linestring_id = "id2")
```

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

### Create Polygon with X, Y, Z, and M Coordinates (Numeric Indices)

Source: https://github.com/dcooley/sfheaders/blob/master/docs/reference/sf_polygon.html

This example shows how to create a polygon geometry using numeric indices for x, y, z, and m coordinates. Pass your data frame to 'obj' and the column indices to 'x', 'y', 'z', and 'm'.

```r
sf_polygon( obj = df, x = 2, y = 3, z = 4, m = 5)
```

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

### Round-trip Multilinestring with Fill and Keep Options

Source: https://github.com/dcooley/sfheaders/blob/master/docs/reference/sf_mline.html

This example shows how to perform a round-trip conversion of a multilinestring object using sf_mline with the `fill = TRUE` and `keep = TRUE` options. This is necessary to preserve all fields during the conversion process.

```R
sf_mline(sf_to_df(sfx, fill = TRUE), keep = TRUE)
```

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

### Create Polygons with Numeric IDs

Source: https://github.com/dcooley/sfheaders/blob/master/docs/reference/sf_polygon.html

This example shows how to use sf_polygon when the polygon and linestring IDs are numeric values instead of strings. The function correctly identifies and uses these numeric IDs to form polygons.

```r
sf_polygon( obj = df, polygon_id = 1, linestring_id = 2 )
```

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

### Create MULTIPOLYGON with only linestring_id

Source: https://github.com/dcooley/sfheaders/blob/master/docs/reference/sfc_multipolygon.html

This example shows how to create a MULTIPOLYGON sfc object when only a linestring_id is provided. The function groups points into linestrings based on this ID.

```R
sfc_multipolygon( df, x = "x", y = "y", linestring_id = "id1")
```

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

### Create Multilinestring with XYZ Coordinates

Source: https://github.com/dcooley/sfheaders/blob/master/docs/reference/sf_mline.html

This example shows how to create a multilinestring object when the input data frame contains XYZ coordinates, as opposed to XYM. Note the comment indicating this gives XYZ, not XYM.

```R
(sfx <- sf_mline( obj = df[-5]))
```

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

### Create MULTIPOLYGON with only polygon_id

Source: https://github.com/dcooley/sfheaders/blob/master/docs/reference/sfc_multipolygon.html

This example demonstrates creating a MULTIPOLYGON sfc object using only the polygon_id. Each unique value in polygon_id will define a separate polygon.

```R
sfc_multipolygon( df, x = "x", y = "y", polygon_id = "id2")
```

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

### Construct sfg MULTIPOLYGON with Z and M coordinates

Source: https://github.com/dcooley/sfheaders/blob/master/docs/reference/sfg_multipolygon.html

This example demonstrates how to construct an sfg MULTIPOLYGON object including both Z and M coordinates. Ensure your data frame has columns for both and specify their names using the 'z' and 'm' arguments.

```R
df <- data.frame(
  polygon_id = c(rep(1, 5), rep(2, 10))
  , line_id = c(rep(1, 10), rep(2, 5))
  , x = c(0,0,1,1,0,2,2,5,5,2,3,3,4,4,3)
  , y = c(0,1,1,0,0,2,5,5,2,2,3,4,4,3,3)
  , z = c(1)
  , m = c(1)
)

sfg_multipolygon(
  df, x = "x", y = "y", z = "z", m = "m", polygon_id = "polygon_id", linestring_id = "line_id"
  )
```

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

### Convert MultiPoint to Polygon using sfc_cast

Source: https://github.com/dcooley/sfheaders/blob/master/docs/reference/sfc_cast.html

This example shows how to convert a multipoint geometry collection (sfc_multipoint) into a polygon geometry using sfc_cast. The output displays the resulting polygon coordinates.

```R
sfc_cast( mpt, "POLYGON" )
#> [[1]]
#> [[1]]
#>       [,1] [,2]
#>  [1,]    0    0
#>  [2,]    0    1
#>  [3,]    1    1
#>  [4,]    1    0
#>  [5,]    1    1
#>  [6,]    1    2
#>  [7,]    2    2
#>  [8,]    2    1
#>  [9,]    0    0
#> 
#> attr(,"class")
#> [1] "XY"      "POLYGON" "sfg"    
#> 
#> [[2]]
#> [[1]]
#>      [,1] [,2]
#> [1,]    3    3
#> [2,]    4    3
#> [3,]    4    4
#> [4,]    3    4
#> [5,]    3    3
#> 
#> attr(,"class")
#> [1] "XY"      "POLYGON" "sfg"    
#> 
#> attr(,"n_empty")
#> [1] 0
#> attr(,"crs")
#> $input
#> [1] NA
#> 
#> $wkt
#> [1] NA
#> 
#> attr(,"class")
#> [1] "crs"
#> attr(,"class")
#> [1] "sfc_POLYGON" "sfc"        
#> attr(,"precision")
#> [1] 0
#> attr(,"bbox")
#> xmin ymin xmax ymax 
#>    0    0    4    4 
#> attr(,"class")
#> [1] "bbox"
```

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

### Create XYZ Polygon using Linestring ID from Data Frame

Source: https://github.com/dcooley/sfheaders/blob/master/docs/reference/sfg_polygon.html

Constructs an SFG polygon from a data frame, using a specified column for linestring IDs and inferring X and Y from other columns. This example also implicitly creates an XYZ geometry.

```R
df <- data.frame( x = 1:12, y = 1:12, z = 13:24, id = c(rep(1,6), rep(2,6)))
sfg_polygon( df, linestring_id = "id" )
```

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

### Create LINESTRING from data frame with specified columns

Source: https://github.com/dcooley/sfheaders/blob/master/docs/reference/sfc_linestring.html

Construct a LINESTRING sfc object from a data frame by explicitly naming the x and y geometry columns. This example also demonstrates how the function handles data frames with an 'id' column.

```R
x <- data.frame( id = 1:2, x = 1:2, y = 2:1 )
sfc_linestring( x, x = "x", y = "y" )
```

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

### Construct sfg MULTIPOLYGON from data frame with explicit column names

Source: https://github.com/dcooley/sfheaders/blob/master/docs/reference/sfg_multipolygon.html

This example shows how to construct an sfg MULTIPOLYGON object from a data frame by explicitly naming the columns for x, y, polygon IDs, and linestring IDs. This provides more control over the geometry construction.

```R
df <- data.frame(
  polygon_id = c(rep(1, 5), rep(2, 10))
  , line_id = c(rep(1, 10), rep(2, 5))
  , x = c(0,0,1,1,0,2,2,5,5,2,3,3,4,4,3)
  , y = c(0,1,1,0,0,2,5,5,2,2,3,4,4,3,3)
  , z = c(1)
  , m = c(1)
)

sfg_multipolygon(
  df, x = "x", y = "y", polygon_id = "polygon_id", linestring_id = "line_id"
  )
```

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

### Create sf_point specifying x and y columns

Source: https://github.com/dcooley/sfheaders/blob/master/docs/articles/examples.html

Shows how to create point geometries when non-geometry columns exist, by explicitly specifying 'x' and 'y'.

```R
df <- data.frame(
  id = c(1,1,2,2,3)
  , x = c(1,1,4,4,1)
  , y = c(1,4,4,1,1)
)

df$val <- letters[ df$id ]

sf_point( df, x = "x", y = "y" )
```

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

### Create sf_linestring keeping all columns

Source: https://github.com/dcooley/sfheaders/blob/master/docs/articles/examples.html

Demonstrates creating linestring geometries while retaining all original columns by setting 'keep = TRUE'.

```R
df <- data.frame(
  id = c(1,1,2,2,3)
  , x = c(1,1,4,4,1)
  , y = c(1,4,4,1,1)
)

df$val <- letters[ df$id ]

sf_linestring( df, x = "x", y = "y", linestring_id = "id", keep = TRUE )
```

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

### Create MULTILINESTRING with explicit object

Source: https://github.com/dcooley/sfheaders/blob/master/docs/reference/sfc_multilinestring.html

Construct a MULTILINESTRING by passing a matrix to the 'obj' argument of sfc_multilinestring. This example demonstrates creating a MULTILINESTRING with Z coordinates.

```R
m <- matrix(c(0,0,0,0,0,1,0,1,1,1,2,2,1,2,3), ncol = 3, byrow = TRUE)
sfc_multilinestring( obj = m )
```

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

### Create sf_linestring specifying x, y, and linestring_id

Source: https://github.com/dcooley/sfheaders/blob/master/docs/articles/examples.html

Illustrates creating linestring geometries by specifying 'x', 'y', and 'linestring_id' columns.

```R
df <- data.frame(
  id = c(1,1,2,2,3)
  , x = c(1,1,4,4,1)
  , y = c(1,4,4,1,1)
)

df$val <- letters[ df$id ]

sf_linestring( df, x = "x", y = "y", linestring_id = "id" )
```

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

### Convert sf MultiLineString to MultiPolygon

Source: https://github.com/dcooley/sfheaders/blob/master/docs/reference/sf_cast.html

This example demonstrates casting an sf MULTILINESTRING object to a MULTIPOLYGON. This operation can be complex and depends on the input data structure.

```R
df <- data.frame(
 id1 = c(1,1,1,1,1,1,1,1,2,2,2,2)
 , id2 = c(1,1,1,1,2,2,2,2,1,1,1,1)
 , x = c(0,0,1,1,1,1,2,2,3,4,4,3)
 , y = c(0,1,1,0,1,2,2,1,3,3,4,4)
)

mls <- sf_multilinestring(obj = df, x = "x", y = "y", multilinestring_id = "id1")
sf_cast( mls, "MULTIPOLYGON" )
```

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

### Construct sf POINT with swapped coordinate columns

Source: https://github.com/dcooley/sfheaders/blob/master/docs/reference/sf_point.html

Demonstrates how to assign columns to x and y coordinates in sf_point, even if they are not in the conventional order.

```R
sf_point( obj = x, x = "y", y = "x" )
```

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

### Filter MultiLineString by IDs

Source: https://github.com/dcooley/sfheaders/blob/master/docs/reference/sf_multilinestring.html

This example shows how to filter MultiLineString objects by specific MultiLineString and LineString IDs. The function returns a data frame with the filtered geometries.

```r
sf_multilinestring( obj = df, multilinestring_id = 1, linestring_id = 2 )
```

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

### Construct MULTIPOINT from data frame (default columns)

Source: https://github.com/dcooley/sfheaders/blob/master/docs/reference/sfc_multipoint.html

When using a data frame, `sfc_multipoint` can infer 'x' and 'y' columns if they exist. This example shows default behavior.

```r
x <- data.frame( id = 1:2, x = 1:2, y = 2:1 )
sfc_multipoint( x )
```

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

### Create an XYZM Linestring sfg

Source: https://github.com/dcooley/sfheaders/blob/master/docs/articles/examples.html

Demonstrates creating a linestring geometry with a measure using numeric coordinates.

```R
sfg_linestring( 1:4 )
#       [,1] [,2] [,3] [,4]
#  [1,]    1    2    3    4
#  attr(,"class")
#  [1] "XYZM"       "LINESTRING" "sfg"
```

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

### Convert sfg Polygon to data.frame

Source: https://github.com/dcooley/sfheaders/blob/master/docs/reference/sfg_to_df.html

Shows how to convert a polygon geometry (sfg) to a data.frame. This example involves creating a matrix for the polygon coordinates and specifying IDs for linestrings.

```R
m <- cbind( matrix( 1:24, ncol = 2 ), c(rep(1, 6), rep(2, 6) ) )
sfg <- sfg_polygon( obj = m, x = 1, y = 2, linestring_id = 3 )
df <- sfg_to_df( sfg )
```

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

### Convert sf MultiPolygon to LineString

Source: https://github.com/dcooley/sfheaders/blob/master/docs/reference/sf_cast.html

This example shows how to cast an sf MULTIPOLYGON object to LINESTRING using sf_cast. This operation effectively extracts the boundary lines of the polygons.

```R
df <- data.frame(
 id1 = c(1,1,1,1,1,1,1,1,2,2,2,2)
 , id2 = c(1,1,1,1,2,2,2,2,1,1,1,1)
 , x = c(0,0,1,1,1,1,2,2,3,4,4,3)
 , y = c(0,1,1,0,1,2,2,1,3,3,4,4)
)

mp <- sf_multipolygon(
 obj = df
 , x = "x"
 , y = "y"
 , multipolygon_id = "id1"
 , linestring_id = "id2"
 , close = FALSE
)
sf_cast( mp, "LINESTRING" )
```

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

### Create an XY Point sfg

Source: https://github.com/dcooley/sfheaders/blob/master/docs/articles/examples.html

Demonstrates creating a 2D point geometry using numeric coordinates.

```R
sfg_point( 1:2 )
#       [,1] [,2]
#  [1,]    1    2
#  attr(,"class")
#  [1] "XY"    "POINT" "sfg"
```

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

### Create an XYZ Point sfg

Source: https://github.com/dcooley/sfheaders/blob/master/docs/articles/examples.html

Demonstrates creating a 3D point geometry using numeric coordinates.

```R
sfg_point( 1:3 )
#       [,1] [,2] [,3]
#  [1,]    1    2    3
#  attr(,"class")
#  [1] "XYZ"   "POINT" "sfg"
```

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

### Update Corrupted Bounding Box Attribute

Source: https://github.com/dcooley/sfheaders/blob/master/docs/reference/sf_bbox.html

This example demonstrates how to update a corrupted bounding box attribute of an sf object using sf_bbox to recalculate the correct bounding box.

```R
attr( mpt, "bbox" ) <- c(1:5)
mpt ## incorrect values

```

```R
attr( mpt, "bbox" ) <- sf_bbox( mpt )
mpt ## back to correct values

```

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

### Construct sf POLYGON specifying x, y, and z columns

Source: https://github.com/dcooley/sfheaders/blob/master/docs/reference/sf_polygon.html

Create a 3D POLYGON by specifying the x, y, and z coordinate columns from a matrix.

```R
sf_polygon( obj = m, x = 1, y = 2, z = 3 )

```

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

### sf_point()

Source: https://github.com/dcooley/sfheaders/blob/master/docs/reference/index.html

Creates an sf POINT object.

```APIDOC
## sf_point()

### Description
Creates an sf POINT object.

### Method
N/A (Function Call)

### Endpoint
N/A

### Parameters
N/A

### Request Example
N/A

### Response
N/A

### Error Handling
N/A
```

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

### Performance benchmark: sfheaders vs data.table

Source: https://github.com/dcooley/sfheaders/blob/master/docs/articles/examples.html

Compares the performance of sfheaders::sf_linestring against a data.table approach for creating linestrings from a large data frame.

```R
n <- 1e5
df <- data.frame(
  id = rep(1:(n/5), each = 5)
  , x = rnorm(n)
  , y = rnorm(n)
)

library(data.table)
library(microbenchmark)

dt <- as.data.table( df )
microbenchmark(

  dt = {
    sf <- dt[
      , {
        geometry <- sf::st_linestring( x = matrix( c( x, y ), ncol = 2, byrow = T ))
        geometry <- sf::st_sf( geometry = sf::st_sfc( geometry ) )
      }
      , by = id
    ]
    sf <- sf::st_as_sf( sf )
  },
  
  sfheaders = {
    sfh <- sfheaders::sf_linestring(
      obj = df
      , linestring_id = "id"
    )
  },
  times = 5
)
```

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

### sf_linestring()

Source: https://github.com/dcooley/sfheaders/blob/master/docs/reference/index.html

Creates an sf LINESTRING object.

```APIDOC
## sf_linestring()

### Description
Creates an sf LINESTRING object.

### Method
N/A (Function Call)

### Endpoint
N/A

### Parameters
N/A

### Request Example
N/A

### Response
N/A

### Error Handling
N/A
```

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

### Construct sf POLYGON with 3D coordinates

Source: https://github.com/dcooley/sfheaders/blob/master/docs/reference/sf_polygon.html

Create a POLYGON with x, y, and z coordinates from a matrix. The matrix should be ordered correctly.

```R
m <- matrix(c(0,0,0,0,0,1,0,1,1,1,2,2,1,2,3,1,3,4), ncol = 3, byrow = TRUE)
sf_polygon( obj = m )

```

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

### Create LINESTRING from data frame with XYZ coordinates

Source: https://github.com/dcooley/sfheaders/blob/master/docs/reference/sfc_linestring.html

This example shows how sfc_linestring can interpret a data frame with 'x', 'y', and 'z' columns to create a 3D LINESTRING sfc object. The function automatically infers the Z dimension.

```R
x <- data.frame( id = 1:2, x = 1:2, y = 2:1 )
sfc_linestring( x )
```

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

### Convert sfg Point to data.frame

Source: https://github.com/dcooley/sfheaders/blob/master/docs/reference/sfg_to_df.html

Demonstrates converting a simple point geometry (sfg) to a data.frame using sfg_to_df. Ensure the sfheaders package is loaded.

```R
sfg <- sfg_point( obj = c(1,2) )
df <- sfg_to_df( sfg )
```

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

### Convert sf object to data frame

Source: https://github.com/dcooley/sfheaders/blob/master/docs/articles/examples.html

Shows how to convert an sf object (linestring in this case) back to a data frame using sf_to_df.

```R
df <- data.frame(
  id = c(1,1,2,2,3)
  , x = c(1,1,4,4,1)
  , y = c(1,4,4,1,1)
)

df$val <- letters[ df$id ]

sf <- sf_linestring( df, x = "x", y = "y", linestring_id = "id", keep = TRUE )

sf_to_df( sf )
```

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

### Create sfg_POINT with C++

Source: https://github.com/dcooley/sfheaders/blob/master/docs/articles/Cpp.html

Use this C++ function to create an sfg_POINT object. It accepts vectors, matrices, or data frames as input.

```cpp
cppFunction(
  includes = '#include "sfheaders/sfg/sfg.hpp"'
  , code = '
    SEXP a_point( SEXP x ) {
      return sfheaders::sfg::sfg_point( x );
    }
  '
  , plugins = "cpp11"
  , depends = c("geometries", "sfheaders")
)
```

```r
a_point( c(1,3) )
#       [,1] [,2]
#  [1,]    1    3
#  attr(,"class")
#  [1] "XY"    "POINT" "sfg"
## single-row matrix
a_point( matrix(c(1,2), ncol = 2) )
#       [,1] [,2]
#  [1,]    1    2
#  attr(,"class")
#  [1] "XY"    "POINT" "sfg"
## single-row data.frame
a_point( data.frame(x = 1, y = 2) )
#       [,1] [,2]
#  [1,]    1    2
#  attr(,"class")
#  [1] "XY"    "POINT" "sfg"
```

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

### Create sf LINESTRING from matrix

Source: https://github.com/dcooley/sfheaders/blob/master/docs/reference/sf_linestring.html

Use this to create a basic LINESTRING sf object from a matrix of coordinates. The matrix should be ordered sequentially for each linestring.

```R
x <- matrix( c(1:8), ncol = 2 )
sf_linestring( x )
```

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

### sf_multipoint()

Source: https://github.com/dcooley/sfheaders/blob/master/docs/reference/index.html

Creates an sf MULTIPOINT object.

```APIDOC
## sf_multipoint()

### Description
Creates an sf MULTIPOINT object.

### Method
N/A (Function Call)

### Endpoint
N/A

### Parameters
N/A

### Request Example
N/A

### Response
N/A

### Error Handling
N/A
```

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

### sf_bbox()

Source: https://github.com/dcooley/sfheaders/blob/master/docs/reference/index.html

Calculates the bounding box for spatial data.

```APIDOC
## sf_bbox()

### Description
Calculates the bounding box for spatial data.

### Method
N/A (Function Call)

### Endpoint
N/A

### Parameters
N/A

### Request Example
N/A

### Response
N/A

### Error Handling
N/A
```

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

### Create Data Frame and Geometry Objects

Source: https://github.com/dcooley/sfheaders/blob/master/docs/reference/sfc_cast.html

This code sets up a data frame and creates various simple feature geometry objects (points, multipoints, linestrings, multilinestrings, polygons, multipolygons) from it. These objects serve as input for the sfc_cast function.

```R
df <- data.frame(
 id1 = c(1,1,1,1,1,1,1,1,2,2,2,2)
 , id2 = c(1,1,1,1,2,2,2,2,1,1,1,1)
 , x = c(0,0,1,1,1,1,2,2,3,4,4,3)
 , y = c(0,1,1,0,1,2,2,1,3,3,4,4)
)

pt <- sfc_point(obj = df, x = "x", y = "y", z = "id1")
mpt <- sfc_multipoint(obj = df, x = "x", y = "y", multipoint_id = "id1")
ls <- sfc_linestring(obj = df, x = "x", y = "y", linestring_id = "id1")
mls <- sfc_multilinestring(obj = df, x = "x", y = "y", multilinestring_id = "id1")
p <- sfc_polygon(
 obj = df
 , x = "x"
 , y = "y"
 , polygon_id = "id1"
 , linestring_id = "id2"
 , close = FALSE
)
mp <- sfc_multipolygon(
 obj = df
 , x = "x"
 , y = "y"
 , multipolygon_id = "id1"
 , linestring_id = "id2"
 , close = FALSE
)
```

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

### Create sf_point from data frame

Source: https://github.com/dcooley/sfheaders/blob/master/docs/articles/examples.html

Demonstrates creating a simple point geometry from a data frame where 'id' is retained.

```R
df <- data.frame(
  id = c(1,1,2,2,3)
  , x = c(1,1,4,4,1)
  , y = c(1,4,4,1,1)
)

sf_point( df )
```

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

### Construct MULTIPOINT from data frame (swapped columns)

Source: https://github.com/dcooley/sfheaders/blob/master/docs/reference/sfc_multipoint.html

Demonstrates how to specify different columns for 'x' and 'y' geometry when constructing a MULTIPOINT sfc object from a data frame.

```r
sfc_multipoint( x, x = "y", y = "x" )
```

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

### Round-trip sf MULTIPOINT using sf_mpt

Source: https://github.com/dcooley/sfheaders/blob/master/docs/reference/sf_mpt.html

Demonstrates converting an sf MULTIPOINT object to a data frame and back using sf_mpt.

```R
## we trivially round-trip with sf_mpt()
sf_mpt(sf_to_df(sfx))
```

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

### sf_mpt()

Source: https://github.com/dcooley/sfheaders/blob/master/docs/reference/index.html

Helper function for creating sf MULTIPOINT objects.

```APIDOC
## sf_mpt()

### Description
Helper function for creating sf MULTIPOINT objects.

### Method
N/A (Function Call)

### Endpoint
N/A

### Parameters
N/A

### Request Example
N/A

### Response
N/A

### Error Handling
N/A
```

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

### Create a simple polygon from a matrix

Source: https://github.com/dcooley/sfheaders/blob/master/docs/reference/sfc_polygon.html

Use a matrix of coordinates to construct a basic POLYGON sfc object. The input matrix should define the vertices of the polygon.

```R
m <- matrix(c(0,0,0,0,1,1), ncol = 2 )
sfc_polygon( m )
```

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

### sfc_point()

Source: https://github.com/dcooley/sfheaders/blob/master/docs/reference/index.html

Creates an sfc POINT object.

```APIDOC
## sfc_point()

### Description
Creates an sfc POINT object.

### Method
N/A (Function Call)

### Endpoint
N/A

### Parameters
N/A

### Request Example
N/A

### Response
N/A

### Error Handling
N/A
```

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

### Create sf POINT from Matrix

Source: https://github.com/dcooley/sfheaders/blob/master/docs/reference/sf_pt.html

Constructs an sf POINT object from a matrix with 'x' and 'y' columns. Handles matrices with 'z' coordinates as well.

```R
x <- cbind(x = 1, y= 3)
sf_pt( x )

```

```R
sf_pt(cbind(x, z = 2))

```

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

### Round-trip sf object with sf_line

Source: https://github.com/dcooley/sfheaders/blob/master/docs/reference/sf_line.html

Demonstrates converting an sf object to a data frame and then back to an sf object using sf_line, preserving the LINESTRING geometries.

```r
sf_line(sf_to_df(sfx))
```

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

### sfg_point()

Source: https://github.com/dcooley/sfheaders/blob/master/docs/reference/index.html

Creates an sfg POINT object.

```APIDOC
## sfg_point()

### Description
Creates an sfg POINT object.

### Method
N/A (Function Call)

### Endpoint
N/A

### Parameters
N/A

### Request Example
N/A

### Response
N/A

### Error Handling
N/A
```

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

### Create an XYZM Point sfg

Source: https://github.com/dcooley/sfheaders/blob/master/docs/articles/examples.html

Demonstrates creating a 3D point geometry with a measure using numeric coordinates.

```R
sfg_point( 1:4 )
#       [,1] [,2] [,3] [,4]
#  [1,]    1    2    3    4
#  attr(,"class")
#  [1] "XYZM"  "POINT" "sfg"
```

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

### sf_pt()

Source: https://github.com/dcooley/sfheaders/blob/master/docs/reference/index.html

Helper function for creating sf POINT objects.

```APIDOC
## sf_pt()

### Description
Helper function for creating sf POINT objects.

### Method
N/A (Function Call)

### Endpoint
N/A

### Parameters
N/A

### Request Example
N/A

### Response
N/A

### Error Handling
N/A
```

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

### sf_line()

Source: https://github.com/dcooley/sfheaders/blob/master/docs/reference/index.html

Helper function for creating sf LINESTRING objects.

```APIDOC
## sf_line()

### Description
Helper function for creating sf LINESTRING objects.

### Method
N/A (Function Call)

### Endpoint
N/A

### Parameters
N/A

### Request Example
N/A

### Response
N/A

### Error Handling
N/A
```

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

### Create an XY Linestring sfg from data frame

Source: https://github.com/dcooley/sfheaders/blob/master/docs/articles/examples.html

Demonstrates creating a 2D linestring geometry from a data frame containing x and y coordinates.

```R
df <- data.frame(
  x = c(1,1,4,4,1)
  , y = c(1,4,4,1,1)
)
sfg_linestring(df)
#       [,1] [,2]
#  [1,]    1    1
#  [2,]    1    4
#  [3,]    4    4
#  [4,]    4    1
#  [5,]    1    1
#  attr(,"class")
#  [1] "XY"         "LINESTRING" "sfg"
```

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

### Convert Points to LineString using sfc_cast

Source: https://github.com/dcooley/sfheaders/blob/master/docs/reference/sfc_cast.html

Demonstrates converting a simple feature geometry collection of points (sfc_point) to a linestring geometry using sfc_cast. The output shows the resulting linestring coordinates.

```R
sfc_cast( pt, "LINESTRING" )
#> [[1]]
#>      [,1] [,2] [,3]
#> [1,]    0    0    1
#> attr(,"class")
#> [1] "XYZ"        "LINESTRING" "sfg"       
#> 
#> [[2]]
#>      [,1] [,2] [,3]
#> [1,]    0    1    1
#> attr(,"class")
#> [1] "XYZ"        "LINESTRING" "sfg"       
#> 
#> [[3]]
#>      [,1] [,2] [,3]
#> [1,]    1    1    1
#> attr(,"class")
#> [1] "XYZ"        "LINESTRING" "sfg"       
#> 
#> [[4]]
#>      [,1] [,2] [,3]
#> [1,]    1    0    1
#> attr(,"class")
#> [1] "XYZ"        "LINESTRING" "sfg"       
#> 
#> [[5]]
#>      [,1] [,2] [,3]
#> [1,]    1    1    1
#> attr(,"class")
#> [1] "XYZ"        "LINESTRING" "sfg"       
#> 
#> [[6]]
#>      [,1] [,2] [,3]
#> [1,]    1    2    1
#> attr(,"class")
#> [1] "XYZ"        "LINESTRING" "sfg"       
#> 
#> [[7]]
#>      [,1] [,2] [,3]
#> [1,]    2    2    1
#> attr(,"class")
#> [1] "XYZ"        "LINESTRING" "sfg"       
#> 
#> [[8]]
#>      [,1] [,2] [,3]
#> [1,]    2    1    1
#> attr(,"class")
#> [1] "XYZ"        "LINESTRING" "sfg"       
#> 
#> [[9]]
#>      [,1] [,2] [,3]
#> [1,]    3    3    2
#> attr(,"class")
#> [1] "XYZ"        "LINESTRING" "sfg"       
#> 
#> [[10]]
#>      [,1] [,2] [,3]
#> [1,]    4    3    2
#> attr(,"class")
#> [1] "XYZ"        "LINESTRING" "sfg"       
#> 
#> [[11]]
#>      [,1] [,2] [,3]
#> [1,]    4    4    2
#> attr(,"class")
#> [1] "XYZ"        "LINESTRING" "sfg"       
#> 
#> [[12]]
#>      [,1] [,2] [,3]
#> [1,]    3    4    2
#> attr(,"class")
#> [1] "XYZ"        "LINESTRING" "sfg"       
#> 
#> attr(,"n_empty")
#> [1] 0
#> attr(,"crs")
#> $input
#> [1] NA
#> 
#> $wkt
#> [1] NA
#> 
#> attr(,"class")
#> [1] "crs"
#> attr(,"class")
#> [1] "sfc_LINESTRING" "sfc"           
#> attr(,"precision")
#> [1] 0
#> attr(,"bbox")
#> xmin ymin xmax ymax 
#>    0    0    4    4 
#> attr(,"class")
#> [1] "bbox"
#> attr(,"z_range")
#> zmin zmax 
#>    1    2 
#> attr(,"class")
#> [1] "z_range"
```

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

### Construct sf POINT from a matrix

Source: https://github.com/dcooley/sfheaders/blob/master/docs/reference/sf_point.html

Provide a matrix to sf_point to create multiple POINT geometries. Each column is treated as a coordinate.

```R
x <- matrix( c(1:10) , ncol = 2 )
sf_point( x )
```

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

### Create sf_multipoint with multipoint_id

Source: https://github.com/dcooley/sfheaders/blob/master/docs/articles/examples.html

Shows how to create multipoint geometries from a data frame, using the 'id' column to group points.

```R
df <- data.frame(
  id = c(1,1,2,2,3)
  , x = c(1,1,4,4,1)
  , y = c(1,4,4,1,1)
)

sf_multipoint( df, multipoint_id = "id" )
```

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

### sfc_linestring()

Source: https://github.com/dcooley/sfheaders/blob/master/docs/reference/index.html

Creates an sfc LINESTRING object.

```APIDOC
## sfc_linestring()

### Description
Creates an sfc LINESTRING object.

### Method
N/A (Function Call)

### Endpoint
N/A

### Parameters
N/A

### Request Example
N/A

### Response
N/A

### Error Handling
N/A
```

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

### Create MultiLineString with X, Y, Z, and M (Column Indices)

Source: https://github.com/dcooley/sfheaders/blob/master/docs/reference/sf_multilinestring.html

This snippet shows how to create a MultiLineString using column indices for x, y, z, and m. This is useful when column names are not readily available or for positional referencing.

```r
sf_multilinestring( obj = df, x = 3, y = 4, z = 5, m = 6 )
```

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

### Create sf_linestring with linestring_id

Source: https://github.com/dcooley/sfheaders/blob/master/docs/articles/examples.html

Illustrates creating linestring geometries from a data frame, using the 'id' column for grouping.

```R
df <- data.frame(
  id = c(1,1,2,2,3)
  , x = c(1,1,4,4,1)
  , y = c(1,4,4,1,1)
)

sf_linestring( df, linestring_id = "id" )
```

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

### sf_boxes

Source: https://github.com/dcooley/sfheaders/blob/master/docs/reference/sf_boxes.html

Returns the bounding box of each geometry.

```APIDOC
## sf_boxes

### Description
Returns the bounding box of each geometry.

### Arguments
* `obj` (sf, sfc or sfg object) - The input geometry object.

### Example
```R
df <- data.frame(
 id1 = c(1,1,1,1,1,1,1,1,2,2,2,2)
 , id2 = c(1,1,1,1,2,2,2,2,1,1,1,1)
 , x = c(0,0,1,1,1,1,2,2,3,4,4,3)
 , y = c(0,1,1,0,1,2,2,1,3,3,4,4)
)

sf_line <- sfheaders::sf_linestring(
 obj = df
 , x = "x"
 , y = "y"
 , linestring_id = "id1"
)

sf_boxes( sf_line )
```
```

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

### Round-trip sf POINT with Properties

Source: https://github.com/dcooley/sfheaders/blob/master/docs/reference/sf_pt.html

Demonstrates a round-trip conversion: converting an sf object with properties back to a data frame and then creating a new sf POINT object, preserving the properties.

```R
## we trivially round-trip with sf_pt()
sf_pt(sf_to_df(sfx, fill = TRUE), keep = TRUE)

```

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

### Create sf_LINESTRING with C++

Source: https://github.com/dcooley/sfheaders/blob/master/docs/articles/Cpp.html

This C++ function constructs an sf_LINESTRING object. It requires input data, optionally geometry columns, and an ID column for grouping.

```cpp
cppFunction(
  includes = '
    #include "sfheaders/sf/linestring/sf_linestring.hpp"
  ',
  code = '
    SEXP a_linestring( SEXP x, SEXP geometry_columns, SEXP id_column ) {
      return sfheaders::sf::sf_linestring( x, geometry_columns, id_column );
    }
  ',
  plugins = "cpp11",
  depends = c("geometries", "sfheaders")
)
```

```r
x <- 1:2
a_linestring( x, NULL, NULL )
#    id geometry
#  1  1     1, 2

x <- matrix(c(1,2,3,4,5,6), ncol = 2)
a_linestring( x, NULL, NULL )
#    id         geometry
#  1  1 1, 2, 3, 4, 5, 6

x <- data.frame(x = 1:6, y = 4:9, id = c(rep(1,3), rep(2,3)))
a_linestring( x, NULL, "id" )
#    id         geometry
#  1  1 1, 2, 3, 4, 5, 6
#  2  2 4, 5, 6, 7, 8, 9

x <- data.frame(x = 1:6, y = 4:9, z = 8:10, id = c(rep(1,3), rep(2,3)))
a_linestring( x, c("x","y"), "id" )
#    id         geometry
#  1  1 1, 2, 3, 4, 5, 6
#  2  2 4, 5, 6, 7, 8, 9

a_linestring( x, c("x","y", "z"), "id" )
#    id                   geometry
#  1  1 1, 2, 3, 4, 5, 6, 8, 9, 10
#  2  2 4, 5, 6, 7, 8, 9, 8, 9, 10
```

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

### sfc_multipoint()

Source: https://github.com/dcooley/sfheaders/blob/master/docs/reference/index.html

Creates an sfc MULTIPOINT object.

```APIDOC
## sfc_multipoint()

### Description
Creates an sfc MULTIPOINT object.

### Method
N/A (Function Call)

### Endpoint
N/A

### Parameters
N/A

### Request Example
N/A

### Response
N/A

### Error Handling
N/A
```

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

### sf_mline()

Source: https://github.com/dcooley/sfheaders/blob/master/docs/reference/index.html

Helper function for creating sf MULTILINESTRING objects.

```APIDOC
## sf_mline()

### Description
Helper function for creating sf MULTILINESTRING objects.

### Method
N/A (Function Call)

### Endpoint
N/A

### Parameters
N/A

### Request Example
N/A

### Response
N/A

### Error Handling
N/A
```

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

### Create LINESTRING from data frame with swapped x and y columns

Source: https://github.com/dcooley/sfheaders/blob/master/docs/reference/sfc_linestring.html

Demonstrates creating a LINESTRING sfc object from a data frame where the 'x' and 'y' column roles are swapped. This highlights the flexibility in mapping data frame columns to geometry axes.

```R
x <- data.frame( id = 1:2, x = 1:2, y = 2:1 )
sfc_linestring( x, x = "y", y = "x" )
```

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

### sf_poly()

Source: https://github.com/dcooley/sfheaders/blob/master/docs/reference/index.html

Helper function for creating sf POLYGON objects.

```APIDOC
## sf_poly()

### Description
Helper function for creating sf POLYGON objects.

### Method
N/A (Function Call)

### Endpoint
N/A

### Parameters
N/A

### Request Example
N/A

### Response
N/A

### Error Handling
N/A
```

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

### Create sfc_LINESTRING with Z and M coordinates

Source: https://github.com/dcooley/sfheaders/blob/master/docs/reference/sfc_linestring.html

Constructs a LINESTRING sfc object from a data frame, specifying columns for X, Y, Z, M, and a linestring identifier. Requires a data frame with at least x, y, z, m, and id columns.

```R
sfc_linestring(df, x = "x", y = "y", z = "z", m = "m", linestring_id = "id")
```

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

### Convert sfc to data frame

Source: https://github.com/dcooley/sfheaders/blob/master/docs/reference/sfc_to_df.html

Demonstrates the basic usage of sfc_to_df to convert an sfc linestring object to a data frame.

```R
x <- matrix( c(1:16), ncol = 2 )
sfc <- sfc_linestring( x )
df <- sfc_to_df( sfc )
```