New answers tagged statistics
Thank you. The CRS was the problem. I had changed the raster then the vector CRS to match them. It had not changed anything. I tried again changing both CRSs into a third CRS (WGS 84), it worked.
I haven't calculated mode values before (most frequently occurring value), but at least for quantile values you could try to use the plugin I coded (LecoS). Although not primarily intended for this use it is able to calculate some "zonal statistics" for polygon overlays. How to: Install numpy and scipy for your System and QGIS. On Windows choose the ...
The v.rast.stats module in GRASS GIS is very powerful and will allow you to calculate univariate statistics (n, min, max, range, mean, stddev, variance, coeff_var, sum) from a raster map based on polygon boundaries.
Arcgis answer is below You have to make the raster an INT to get and Median. Use the INT function then use zonal stats as table. Join the table back to the vectors if you want to map the median but this seems redundant. To get mode just build a vat (Build a Value Attribute Table) table after you run INT organize the count in descending order.
Most likely the vector file is topologically broken. Try and repair it first, and then retry. The link provides a short guide on how to accomplish it with grass toolbox. How to check Topology in QGIS?
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