[GRASS-dev] pygrass: append new point to map of points

[Pietro]

Soory for the delay,

On Fri, Jan 30, 2015 at 3:52 PM, Moritz Lennert
<mlennert at club.worldonline.be> wrote:
> Is it possible in pygrass to append a new point to a map of points (same for
> other features) ? Or do I have to get all the features of a map, and the new
> feature, and then write all features to a new map ?

Yes, here an example, write a new map:

{{{
>>> from grass.pygrass.vector.geometry import Point
>>> from grass.pygrass.vector import VectorTopo
>>> with VectorTopo('mypoits', mode='w') as my:
...     my.write(Point(0, 10))
...     my.write(Point(5, 15))
...

}}}

read an existing map:

{{{
>>> with VectorTopo('mypoits', mode='r') as my:
...    for p in my:
...        print(p)
...
POINT(0.000000 10.000000)
POINT(5.000000 15.000000)
}}}

Add some new point to an existing map:

{{{
>>> with VectorTopo('mypoits', mode='rw') as my:
...    my.write(Point(10, 10))
...    my.write(Point(15, 15))
...
}}}

and read again the modified map:

{{{
>>> with VectorTopo('mypoits', mode='r') as my:
...    for p in my:
...        print(p)
...
POINT(0.000000 10.000000)
POINT(5.000000 15.000000)
POINT(10.000000 10.000000)
POINT(15.000000 15.000000)
}}}

All the best

Pietro