[Qgis-user] random locations sample from the actual map

[richard burcher]

Hi Chathura,

For vector data try the fTools. Look under Vector -- Research Tools, there
are several ie Random Selection & Random Selection within subsets. This
would do for selecting already present polygon/point type features & export
selected layer from table of contents as a new layer.

To select only a range of coordinates (point based data) you can add the x &
y columns to attribute table. select layer for edit, add column of type real
(remember to set precision to > 2) & from Geometry group in Function list
window select $x or $y. Save & stop editing, you may notice that the columns
go null -- this is a bug (i'm using 1.8 windows 7), close & reopen attribute
table. You can now use the query builder to filter out a range of values,
export selection & apply the fTools discussed above. 

For more advanced options I would look at the mangeR plugin.

Plugins of interest:
Point Sampling tool
Spatial Data Analysis for point pattern -- very extensive functionality


Cheers,

Richard



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