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I have a raster layer of landuse and a vector layer of areas of interest. I would like to calculate for each polygon (areas of interest) the proportion or number of cells of the raster for each category. I would like to get a table of areas in rows, raster categories in column and the number / proportion of cell for each combination.

I'm sure there is an easy way to do that but I couldn't find it. All I got was global statistics through Zonal Stats but I couldn't calculate per category.

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I had a very similar situation, and came across this answer

Essentially, you have to create an indicator gird of 0s and 1s, for each of your landuse types. And then use a combination of Count and Sum from the Zonal Statistics plugin. Count will give total number of raster cells in each polygon, and Sum will give number of cells = 1. You can then determine proportion of cover within each polygon. Maybe a bit cumbersome if you have a lot of landuse types, but straightforward.


Edit

As of QGIS 3.2 there is a Zonal Histogram tool which should perform this automatically, saving the need to create multiple indicator grids.

  • The Zonal Histogram is a perfect tool in QGIS 3.x for zonal analysis. – nickan Aug 19 at 7:30

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