Docs for ‘QGIS testing’. Visit http://docs.qgis.org/2.18 for QGIS 2.18 docs and translations.

Raster

Hypsometric curves

Description

Calculate hypsometric curves for features of polygon layer and save them as CSV file for further processing.

Parameters

DEM to analyze [raster]
DEM to use for calculating altitudes.
Boundary layer [vector: polygon]
Polygonal vector layer with boundaries of areas used to calculate hypsometric curves.
Step [number]

Distance between curves.

Default: 100.0

Use % of area instead of absolute value [boolean]

Write area percentage to “Area” field of the CSV file instead of absolute area value.

Default: False

Outputs

Output directory [directory]

Directory where output will be saved. For each feature from input vector layer CSV file with area and altitude values will be created.

File name consists of prefix hystogram_ followed by layer name and feature ID.

Console usage

processing.runalg('qgis:hypsometriccurves', input_dem, boundary_layer, step, use_percentage, output_directory)

See also

Raster layer statistics

Description

Calculates basic statistics of the raster layer.

Parameters

Input layer [raster]
Raster to analyze.

Outputs

Statistics [html]
Analysis results in HTML format.
Minimum value [number]
Minimum cell value.
Maximum value [number]
Maximum cell value.
Sum [number]
Sum of all cells values.
Mean value [number]
Mean cell value.
valid cells count [number]
Number of cells with data.
No-data cells count [number]
Number of NODATA cells.
Standard deviation [number]
Standard deviation of cells values.

Console usage

processing.runalg('qgis:rasterlayerstatistics', input, output_html_file)

See also

Zonal Statistics

Description

Calculates some statistics values for pixels of input raster inside certain zones, defined as polygon layer.

Following values calculated for each zone:

  • minimum
  • maximum
  • sum
  • count
  • mean
  • standard deviation
  • number of unique values
  • range
  • variance

Parameters

Raster layer [raster]
Raster to analyze.
Raster band [number]

Number of raster band to analyze.

Default: 1

Vector layer containing zones [vector: polygon]
Layer with zones boundaries.
Output column prefix [string]

Prefix for output fields.

Default: _

Load whole raster in memory [boolean]

Determines if raster band will be loaded in memory (True) or readed by chunks (False). Useful only when disk IO or raster scanning inefficiencies are your limiting factor.

Default: True

Outputs

Output layer [vector]
The resulting layer. Basically this is same layer as zones layer with new columns containing statistics added.

Console usage

processing.runalg('qgis:zonalstatistics', input_raster, raster_band, input_vector, column_prefix, global_extent, output_layer)

See also