PyQGIS: Get Raster Band Statistics

Objectives:

• Get statistics for a raster band

Open the QGIS Python Console

From the menu, select Plugins -> Python Console, or Ctrl + Alt + P (Windows)

You can type directly into the console, or select the pad and paper icon to write code in the editor. I prefer to write code in the editor because it allows me to save my work and run a compilation of commands.

Load a raster layer

Define the path to a raster

In the code editor, or console, create a variable containing the path to your raster file.

fn = 'c:/path/to/raster/file.tif'

Load raster into QGIS interface

Now we’ll simultaneously assign the raster layer to the rlayer variable and load it into the QGIS interface.

rlayer = iface.addRasterLayer(fn, 'layer name')

This adds the raster into the QGIS interface. In the legend, the raster is labeled ‘layer name’.

Get raster band statistics

PyQGIS makes it very easy to get statistics from a raster band, we simply need to call bandStatistics() on the raster layer’s data provider. We give two arguments, the band number and the statistic to return. I find it’s easiest to return all the band statistics, then access the specific statistics from the object that is returned.

#get statistics for raster band 1
stats = rlayer.dataProvider().bandStatistics(1, QgsRasterBandStats.All)

No we can access specific statistics, such as minimum, maximum, and mean using the stats variable.

print(stats.minimumValue)
print(stats.minimumValue)
print(stats.mean)
print(stats.range)
print(stats.stdDev)
print(stats.sum)
print(stats.sumOfSquares)

Video tutorial

See this tutorial described in a video.