[GRASS-user] Categorize vector map and print with color gradient

[Steffen John]

Hi List!
I'm facing some problems while printing a vector map. I have a map with 
a polygon grid with a number in one column (this is a count of points 
which lies within each grid cell).
I would like to print this vector map with a colour gradient e.g. from 
white to blue. The categorisation should be done automatically with a 
specific mode (e.g. natural breaks, quantiles) and the number of classes 
has to be customisable.

Is there is possibility/function which does this with a vector layer as 
input?

I have found a workaround with raster maps, but even there was no 
possibility for an automatic classification (at least I didn't find).

Thanks in advance!