t.rast.univar.1grass - Man Page

Calculates univariate statistics from the non-null cells for each registered raster map of a space time raster dataset.

Keywords

temporal, statistics, raster, time, parallel

t.rast.univar t.rast.univar --help t.rast.univar [-eru] input=name [zones=name] [nprocs=integer] [output=name] [percentile=float[,float,...]] [where=sql_query] [region_relation=string] [separator=character] [--overwrite] [--help] [--verbose] [--quiet] [--ui]

Flags

-e: Calculate extended statistics
-r: Use the raster map regions for univar statistical calculation instead of the current region
-u: Suppress printing of column names
--overwrite: Allow output files to overwrite existing files
--help: Print usage summary
--verbose: Verbose module output
--quiet: Quiet module output
--ui: Force launching GUI dialog

Parameters

input=nameÂ [required]: Name of the input space time raster dataset
zones=name: Raster map used for zoning, must be of type CELL
nprocs=integer: Number of threads for parallel computing
Default: 1
output=name: Name for output file
percentile=float[,float,...]: Percentile to calculate (requires extended statistics flag)
Options: 0-100
where=sql_query: WHERE conditions of SQL statement without ’where’ keyword used in the temporal GIS framework
Example: start_time > ’2001-01-01 12:30:00’
region_relation=string: Process only maps with this spatial relation to the current computational region
Options: overlaps, contains, is_contained
separator=character: Field separator character between the output columns
Special characters: pipe, comma, space, tab, newline
Default: pipe

Description

t.rast.univar calculates univariate statistics from the non-null cells for each registered raster map of a space time raster dataset.

By default it returns the name of the map, the semantic label of the map, the start and end date of the map and the following values: mean, minimum and maximum vale, mean_of_abs, standard deviation, variance, coeff_var, number of null cells, total number of cells.

Using the e flag it can calculate also extended statistics: first quartile, median value, third quartile and percentile 90.

If a zones raster map is provided, statistics are computed for each zone (category) in that input raster map. The zones option does not support space time raster datasets (STRDS) but only a single, static raster map.

Space time raster datasets may contain raster maps with varying spatial extent like for example series of scenes of satellite images. With the region_relation option, computations can be limited to maps of the space time raster dataset that have a given spatial relation to the current computational region. Supported spatial relations are:

"overlaps": process only maps that spatially overlap ("intersect") with the current computational region
"is_contained": process only maps that are fully within the current computational region
"contains": process only maps that contain (fully cover) the current computational region

Example

Obtain the univariate statistics for the raster space time dataset "tempmean_monthly" (precision reduced to 2 decimals in this example):

t.rast.univar -e tempmean_monthly
id|start|end|mean|min|max|mean_of_abs|stddev|variance|coeff_var|sum|null_cells|cells|first_quartile|median|third_quartile|percentile_90
2009_01_tempmean@climate_2009_2012|2009-01-01 00:00:00|2009-02-01 00:00:00|3.90|-3.38|7.43|3.95|1.79|3.20|45.91|1977967.31|503233|1010600|2.80|3.92|5.21|6.23
2009_02_tempmean@climate_2009_2012|2009-02-01 00:00:00|2009-03-01 00:00:00|5.91|-1.82|8.01|5.92|1.63|2.65|27.53|2999555.60|503233|1010600|5.44|6.26|7.07|7.48
...
2012_11_tempmean@climate_2009_2012|2012-11-01 00:00:00|2012-12-01 00:00:00|8.03|1.79|10.91|8.03|1.32|1.73|16.41|4072472.77|503233|1010600|7.49|8.13|8.96|9.48
2012_12_tempmean@climate_2009_2012|2012-12-01 00:00:00|2013-01-01 00:00:00|8.71|1.76|11.98|8.71|1.72|2.95|19.74|4418403.77|503233|1010600|7.84|8.95|9.99|10.67