[GRASS-user] Calculate Median values in a State

GRASS GRASS user
1

Hi All,

I want to calculate the median precipitation value from a raster layer in each state/province in a vector layer.

How would I go about doing this?

Should I convert the vector layer to a raster and then overlay the layers?

I would appreciate the help.

Thanks,

Andrew

Andrew Lewin, M.Sc., Adv. Dipl. GIS
Email: andrew.lewin@sympatico.ca
Tel: (905) 639-4646
Mobile: (905) 630-8441
Skype: andrew.lewin99

2

Il giorno Tue, 16 Mar 2010 10:46:15 -0400
Andrew Lewin <andrew.lewin@sympatico.ca> ha scritto:

maybe v.rast.stats [1]
Calculates univariate statistics from a GRASS raster map
based on vector polygons and uploads statistics to new attribute
columns.

[1] http://grass.itc.it/grass65/manuals/html65_user/v.rast.stats.html

Hi All,

I want to calculate the median precipitation value from a raster
layer in each state/province in a vector layer.

How would I go about doing this?

Should I convert the vector layer to a raster and then overlay the
layers?

I would appreciate the help.

Thanks,

Andrew

Andrew Lewin, M.Sc., Adv. Dipl. GIS
Email: andrew.lewin@sympatico.ca
Tel: (905) 639-4646
Mobile: (905) 630-8441
Skype: andrew.lewin99

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3

On 03/16/2010 04:46 PM, Andrew Lewin wrote:

Hi All,

I want to calculate the median precipitation value from a raster layer in each state/province in a vector layer.

How would I go about doing this?

v.rast.stats
From the manual:
Nine columns are generated (n, min, max, range, mean, stddev, variance, coeff_var, sum) according to the output of r.univar.

Should I convert the vector layer to a raster and then overlay the layers?

I would appreciate the help.

Thanks,

Andrew

Andrew Lewin, M.Sc., Adv. Dipl. GIS
Email: andrew.lewin@sympatico.ca
Tel: (905) 639-4646
Mobile: (905) 630-8441
Skype: andrew.lewin99

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