Dear Angelo,

your idea is good, but maybe it works better in the other way.

You can use "raster to polygon" to convert the (2) class 1 raster, then "clip" this polygon with the aministrative boundaries and in the end calculate the final area.

Dear Angelo,

with the shapefile already converted to raster, you can calculate a contingency table, e.g. using TabulateArea() in ArcGIS or crosstab() in R. This should return the area of each class within each (rasterized) polygon of your shapefile. Have a look at

http://desktop.arcgis.com/en/arcmap/10.3/tools/spatial-analyst-toolbox/tabulate-area.htm

or

https://www.rdocumentation.org/packages/raster/versions/2.6-7/topics/crosstab

for details...

Best regards

Dear Angelo,

In addition to raster::crosstab() function that Sebastian suggested, one another solution in R is the following:

1) Use raster::mask(x, mask) for clipping the raster with the polygon.

2) Subset the raster: r2

Thank you very much for your replies.

I will try all your suggestions.

(Also, thank you for mentioning to be careful with the projection Ákos Bede-Fazekas )

Why not just clip the raster with the .shp file; then use the Count field x area of 1 cell to calculate the area of Class 1?

1. Clip the raster within boundaries.

2. Use zonal() function from raster package for R in such way: zonal(rst2, rst2, 'count')

3. Multiply pixel count for map class 1 by pixel area.