{"id":2042,"date":"2025-03-31T19:02:52","date_gmt":"2025-03-31T17:02:52","guid":{"rendered":"https:\/\/hannes.enjoys.it\/blog\/?p=2042"},"modified":"2025-03-31T21:00:50","modified_gmt":"2025-03-31T19:00:50","slug":"calculate-the-percentage-of-cells-per-value-category-in-a-raster-in-qgis","status":"publish","type":"post","link":"https:\/\/hannes.enjoys.it\/blog\/2025\/03\/calculate-the-percentage-of-cells-per-value-category-in-a-raster-in-qgis\/","title":{"rendered":"Calculate the percentage of cells per value category in a raster in QGIS"},"content":{"rendered":"\n

Kristian Evers asked on the fediverse<\/a>: <\/p>\n\n\n\n

\n

I have a raster where each cell is categorized with a value of either 1, 2 or 3.<\/p>\n\n\n\n

In #QGIS<\/a>, how would I determine the percentage of cells in each category?<\/p>\n<\/blockquote>\n\n\n\n

This piqued my curiosity so here you go!<\/p>\n\n\n\n

The Raster layer unique values report<\/a> tool provides both a table containing value<\/code> & count<\/code> columns and a number of outputs, among other things TOTAL_PIXEL_COUNT<\/code> and NODATA_PIXEL_COUNT<\/code>.<\/p>\n\n\n

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\"\"<\/figure>\n<\/div>\n\n
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\"\"
Unique values tables for a UInt16 raster<\/figcaption><\/figure>\n<\/div>\n\n\n

The Field calculator can be used to calculate an additional column for the table. Note that I decided for NODATA<\/code> pixels to not<\/strong> count towards the total number of pixels here!<\/p>\n\n\n\n

\"\"<\/figure>\n\n\n\n

Combine them in a model, add appropriate inputs and you have a fancy new QGIS tool to calculate the percentages of each value in a raster image:<\/p>\n\n\n

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\"\"<\/figure>\n<\/div>\n\n
\n
\"\"<\/figure>\n<\/div>\n\n\n

Here is my model file: <\/p>\n\n\n\n

Percentage of cells per value category.model3<\/a>Download<\/a><\/div>\n","protected":false},"excerpt":{"rendered":"

Kristian Evers asked on the fediverse: I have a raster where each cell is categorized with a value of either 1, 2 or 3. In #QGIS, how would I determine the percentage of cells in each category? This piqued my curiosity so here you go! The Raster layer unique values report tool provides both a […]<\/p>\n","protected":false},"author":1,"featured_media":0,"comment_status":"open","ping_status":"open","sticky":false,"template":"","format":"standard","meta":{"footnotes":""},"categories":[29,31],"tags":[],"class_list":["post-2042","post","type-post","status-publish","format-standard","hentry","category-gis","category-qgis"],"_links":{"self":[{"href":"https:\/\/hannes.enjoys.it\/blog\/wp-json\/wp\/v2\/posts\/2042","targetHints":{"allow":["GET"]}}],"collection":[{"href":"https:\/\/hannes.enjoys.it\/blog\/wp-json\/wp\/v2\/posts"}],"about":[{"href":"https:\/\/hannes.enjoys.it\/blog\/wp-json\/wp\/v2\/types\/post"}],"author":[{"embeddable":true,"href":"https:\/\/hannes.enjoys.it\/blog\/wp-json\/wp\/v2\/users\/1"}],"replies":[{"embeddable":true,"href":"https:\/\/hannes.enjoys.it\/blog\/wp-json\/wp\/v2\/comments?post=2042"}],"version-history":[{"count":3,"href":"https:\/\/hannes.enjoys.it\/blog\/wp-json\/wp\/v2\/posts\/2042\/revisions"}],"predecessor-version":[{"id":2053,"href":"https:\/\/hannes.enjoys.it\/blog\/wp-json\/wp\/v2\/posts\/2042\/revisions\/2053"}],"wp:attachment":[{"href":"https:\/\/hannes.enjoys.it\/blog\/wp-json\/wp\/v2\/media?parent=2042"}],"wp:term":[{"taxonomy":"category","embeddable":true,"href":"https:\/\/hannes.enjoys.it\/blog\/wp-json\/wp\/v2\/categories?post=2042"},{"taxonomy":"post_tag","embeddable":true,"href":"https:\/\/hannes.enjoys.it\/blog\/wp-json\/wp\/v2\/tags?post=2042"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}