I have a raster with many classes and I want to know the area or the number of cells for each class. I found quite a few posts on this topic (see links below). None of the suggestions matched my wishes. I do not want to convert to vector since my raster is fairly big. I am looking for a tool similar to the summarize functions available for vector data, with a table as output.

The raster is a 32bit float tif with 5 unique values (1.0, 2.0, 3.0, 4.0 and 5.0) as classes as a result of classification with QGIS SAGA-Toolbox.

QGIS solutions are preferred. Related posts:

Calculating raster area?

Calculating area of vegetation in raster file?

Calculating area of rasters in QGIS?

  • Can you provide an example (screenshot) of the attribute table of your raster? My guess is that this can be done with python, using cursors. – Delonix R. Jun 20 '16 at 12:29
  • I see your point. I have no attribute table available. Probably due to the floating point raster. Maybe this is my problem. – EikeMike Jun 20 '16 at 12:33
  • You can still classify ranges in your raster, either using python or the "Field Calculator". – Delonix R. Jun 20 '16 at 13:08
  • In arcgis use raster calculator int(). Result will have a table – FelixIP Jun 20 '16 at 20:02
  • By asking how to do this in two desktop GIS products you are effectively asking two questions which goes against the Tour. If you focus your question on one product or other then I think it should be possible to re-open and be more liakely to attract a potential answerer. – PolyGeo Sep 24 '16 at 22:35

You can use GRASS GIS r.stats as a plugin in QGIS or in stand alone GRASS:

r.stats calculates the area present in each of the categories of user-selected raster map layer(s). Area statistics are given in units of square meters and/or cell Counts

If you need more options like different units use r.report:

r.report allows the user to set up a series of report parameters to be applied to a raster map layer, and creates a report.

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