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i know i can churn out raster statistics with r.report in GRASS GIS and QGIS, but what i want is the statistics of manually-defined categories of pixel ranges.

what i have is a clipped raster (of a single band) with a range of values that has not been classified. i only know how to categorize the pixels by going to the style tab, and what i want is a count of pixels in each category that i have defined.

to elaborate further, i about ~80,000 pixels and a maximum pixel value of ~25. i want to categorize my pixels like this:

(1) no value - pixel value range 0.0 - 1.5 (2) low value - pixel value range 1.6 - 6.5 (3) medium value - pixel value range 6.6 - 15.0 (4) high value - pixel value range 15.1 - 25.0

now i want a count of the number of pixels in each category. how do i produce that statistical report? i tried the "zonal raster statistics" tool but there's something amiss here. (See attached image for an idea of what i get with a simple r.report of my raster)

I am an amateur in GIS!

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    Perhaps you can first reclassify the raster using Reclassify by table then run r.report on the reclassified output. – Kazuhito Aug 29 at 12:11
  • raster layers unique values report will generate table with stats for each unique value of the raster, which you could group and summarize in excel. – csk Aug 29 at 16:35
  • "reclassify by table" does not work, i get an error message: "[Errno 13] Permission denied: u'tmp1567126975518' See log for more details" – tree123456789 Aug 30 at 1:03
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You can use the Raster Calculator in QGIS to classify your raster and then use the GRASS tool r.report as you've used, or I believe r.describe to generate a report for each class. For example the snapshot below shows a Raster Calculator setup for your classes. Depending on your data it's probably best not to leave gaps in the bounds for each class too ... i.e.

Class 1: >= 0 and < 1.5

Class 2: >= 1.5 and < 6.5

...

See also: QGIS Raster Calculator Help

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