Point on line closest to point?

[Antony Chrysochoou]

Hi, 

Is there a way I can achieve this the latest geoscript? I am using python by the way.

I am aware of the geom.distance(geom) function but it ain't enough. 

Also, There is no projection/interpolation method to follow the shapely example (http://stackoverflow.com/questions/24415806/coordinate-of-the-closest-point-on-a-line)

And I have looked into the linear referencing docs that are around - https://en.wikipedia.org/wiki/Distance_from_a_point_to_a_line, http://stackoverflow.com/questions/7142028/point-on-a-line-closest-to-x-y

Any thoughts would be much appreciated!

Thanks in advance. 

[Justin Deoliveira]

Hey Antony,

It doesn’t look like there is a geoscript method for this, but I do think that jts has the functions you need. In particular:

http://www.vividsolutions.com/jts/javadoc/com/vividsolutions/jts/linearref/LocationIndexedLine.html

I could be off here but the geoscript py code that would do this is:

from com.vividsolutions.jts.linearref import *
from geoscript.geom import *

l = LineString(…)
p = Point(…)

lineIndex = LocationIndexedLine(l)
location = lineIndex.project(p.coordinate) 

closest = Point(location.getCoordinate(l))

Does that look right?

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[jericks]

I added a few linear referencing methods but I don't think they are in the latest release:

https://github.com/geoscript/geoscript-py/pull/40

Jared

[Justin Deoliveira]

Ahhhh… right :) I really need to do a release. I’ll throw this on my todo list.

[Antony Chrysochoou]

Thank you for your fast reply. 

Yes, indeed the jts.linearref did the trick. 

Amazing, thanks for pointing this out

Cheers,
A