line-interpolate-points
v1.0.5
Published
Exposes a function to interpolate any number of points along a multi-segment line (LineString).
Downloads
2,197
Readme
line interpolate points
A Node module that interpolates the coordinates of any number of equidistant points along a line composed of one or
more line segments, at an optional offset. It's particularly useful for GIS applications, and is analogous to the
PostGIS ST_LineInterpolatePoint()
and Python Shapely's shapely.geometry.LineString.interpolate()
. Here's an example
of points interpolated over different multi-segment lines (the second group has been offset):
the api
The module exports a single function, interpolateLineRange( ctrlPoints, number, offsetDist )
.
ctrlPoints
is an array of 2D point arrays, like[ [ 5, 10 ], [ 7, 10 ], [ 14, 13 ] ]
number
is the number of points to interpolate (the endpoints included)offsetDist
is an optional distance to move each interpolated point from its container line segment.minGap
is an optional minimum distance to maintain between subsequent interpolated points (offsetDist
is not taken into account here, as spacing between points is measured along the LineString). May decreasenumber
if the gap between neighbors with that number of points would be lower thanminGap
.
> var interpolateLineRange = require( 'line-interpolate-points' )
> interpolateLineRange( [ [ 3, 10 ], [ 4, 10 ] ], 2 )
[ [ 3, 10 ], [ 4, 10 ] ]
> interpolateLineRange( [ [ 3, 10 ], [ 4, 10 ] ], 4 )
[ [ 3, 10 ],
[ 3.3333333333333335, 10 ],
[ 3.666666666666667, 10 ],
[ 4, 10 ] ]
> interpolateLineRange( [ [ 4, 4 ], [ 4, 10 ], [ 7, 17 ] ], 6, 1 )
[ [ 3, 4 ],
[ 3, 6.723154621172782 ],
[ 3, 9.446309242345563 ],
[ 3.9354486533919397, 12.387971226535829 ],
[ 5.008151811686941, 14.890945262557498 ],
[ 6.080854969981942, 17.393919298579167 ] ]
Install Dev Dependencies
$ npm install
Contributing
Please fork and pull request against upstream master on a feature branch. Please provide unit tests and script fixtures
in the test
directory.
Running Unit Tests
$ npm test
Continuous Integration
Travis tests every release against node version 0.10