[Gvsig_english] Problems importing a polygon grid file

[Simon Cropper (The fosGIS Workflow Guides)]

On 04/05/11 01:37, Sal Garfi wrote:
> Thanks for this. I have created a new grid in Sextante, but the numbering of
> the grid squares in the file from DIVA seems to be different from the
> numbering in Sextante, so the distributins aren't right.

According to the DIVA-GIS manual (on Page 23) you can export a DIVA Grid 
to an ESRI Shapefile. If you did this you would be able to virew in OADE 
gvSIG and have the same polygon numbering.

> For the time being,
> I'm recreating the distributions from scratch with Sextante's 'Count points
> in polygons' function. This works well for density of points in grid
> squares, but I don't know how to recreate 'Richness', as in DIVA,
> representing number of different types of objects recorded at each point. In
> DIVA this would be richness, ie variety of plant species, as an example.

I am not sure of any summary program to do this type of analysis.

The way I would do this is create an extra field in the point layer and 
fill it with the code representing the polygon they are contained in; 
then I would export it to a table for further analysis.

If you got it into a database you could conduct simple SQL queries to 
summarise the data anyway you needed.

The simplest method if you are unfamiliar with databases is to open the 
point layers dbf file with LO/OO Calc or Excel (remember not to save the 
file as the same name or or shapefile may not open again). You can then 
summarise the data in that program using Pivot Tables, etc.


-- 
Cheers Simon

    Simon Cropper
    Website Administrator
    http://gis.fossworkflowguides.com
    The fosGIS Workflow Guide