positions

A collection of positions is an array of valid GeoJSON positions.

This module provides utilities to validate, deduplicate, truncate and reproject collections of positions.

isValidPositions

Signature

isValidPositions(positions)

Description

Returns whether a value is an array whose elements are all valid positions.

An empty array is considered valid.

Parameters

Name	Type	Required	Description
positions	any	yes	Value to test

Returns

Type	Description
boolean	true if the value is an array of valid positions

Examples

isValidPositions([
  [2.3522, 48.8566],
  [2.2945, 48.8584]
])
// true

isValidPositions([
  [2.3522, 48.8566],
  [2.2945]
])
// false

isValidPositions([])
// true

deduplicatePositions

Signature

deduplicatePositions(positions, options = {})

Description

Removes consecutive duplicate positions from a collection.

Two consecutive positions are considered identical according to isSamePosition(). The first occurrence is preserved and subsequent consecutive duplicates are discarded.

Only adjacent duplicates are removed; identical positions separated by other positions are left unchanged.

Parameters

Name	Type	Required	Description
positions	Array	yes	Collection of positions
options.precision	number	no	Decimal precision used for comparison. Defaults to DEFAULT_COORDINATE_PRECISION
options.consider3D	boolean	no	Whether altitude is considered during comparison. Defaults to false

Returns

Type	Description
Array	A new array with consecutive duplicates removed

Throws

Throws if options does not match the expected schema.

Examples

deduplicatePositions([
  [0, 0],
  [0, 0],
  [1, 1],
  [1, 1],
  [2, 2]
])
// [[0, 0], [1, 1], [2, 2]]

truncatePositions

Signature

truncatePositions(positions, options = {})

Description

Truncates every coordinate of every position to the requested precision.

Each position is truncated using truncatePosition(). Because truncatePosition() mutates its input, the positions contained in the input array are modified in place.

Consecutive duplicate positions can optionally be removed after truncation.

Parameters

Name	Type	Required	Description
positions	Array	yes	Collection of positions
options.precision	number	no	Number of decimal places. Defaults to DEFAULT_COORDINATE_PRECISION
options.deduplicate	boolean	no	Remove consecutive duplicate positions after truncation. Defaults to false
options.consider3D	boolean	no	Consider altitude when deduplicating. Defaults to false

Returns

Type	Description
Array	Array of truncated positions

Throws

Throws if positions is not an array or if options does not match the expected schema.

Examples

truncatePositions([
  [2.3522345, 48.8566789],
  [2.3522456, 48.8566891]
], { precision: 3 })
// [[2.352, 48.856], [2.352, 48.856]]

truncatePositions([
  [2.3522345, 48.8566789],
  [2.3522456, 48.8566891]
], { precision: 3, deduplicate: true })
// [[2.352, 48.856]]

reprojectPositions

Signature

reprojectPositions(positions, source, target)

Description

Reprojects every position from a source projection to a target projection using reprojectPosition().

Both projections must already be registered.

Parameters

Name	Type	Required	Description
positions	Array	yes	Collection of positions
source	string	yes	Source projection name
target	string	yes	Target projection name

Returns

Type	Description
Array	A new array containing the reprojected positions

Throws

Throws if positions is not an array or if a position or projection is invalid.

Examples

reprojectPositions([
  [2.3522, 48.8566],
  [2.2945, 48.8584]
], 'EPSG:4326', 'EPSG:3857')
// array of projected positions