[GRASS-user] v.extract how to extract points one by one following their FID number

[Patrick Giraudoux]

Dear all,

Now, I am very happy  with a programme running (this is my first real 
programme in GRASS with a GUI, etc) that can sweep multiple radius 
buffers over points selected one by one from a point vector map and 
save  the pixel count of each category of the overlapping raster in  a 
text file. However, the point selection process is based on the category 
values of the vector file. Example:

 v.extract -t in=$vector out=essaisV list=$count type=point --o --q 
2>/dev/null # point extraction

where $count is incremented from 1 to the number of points.

This could be messy if two different points have the same category value 
(I currently manage to get category value unique and ranging from 1 to 
the number of points, so that each point is extracted alone).

I wonder if it would be possible to make it in a safer way, e.g. to 
extract vectors as does v.extract but with a selection grounded on the 
unique FID number of each point (and not on its category value as e.g. 
with 'list=1' in v.extract). This means to read the FID numbers of a 
point vector map and then to extract stepwise each vector point to a new 
vector map calling it via its FID.

Any hint appreciated,

Cheers,

Patrick