temporal: add granularity and start options to t.rast.univar #3042#7244
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selma-Bentaiba wants to merge 1 commit intoOSGeo:mainfrom
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temporal: add granularity and start options to t.rast.univar #3042#7244selma-Bentaiba wants to merge 1 commit intoOSGeo:mainfrom
selma-Bentaiba wants to merge 1 commit intoOSGeo:mainfrom
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Apr 3, 2026
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I did not go through everything in detail yet. Here are some comments...
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| # When the user asks for granularity, we group maps into time windows | ||
| # and later feed each group as a comma-joined list to r.univar. | ||
| # No new rasters written to disk — that's the whole point of this feature. |
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| # No new rasters written to disk — that's the whole point of this feature. |
| granule_groups = None | ||
| if granularity and rows: | ||
| # Snap the start of the first window to the requested granularity | ||
| # unless the user gave an explicit start time |
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I would argue against adding a start option.
When the granularity option is added, a sampling option would make sense, but start less so. Start can be picked up from first map in series selected by temporal where...
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We're trying to solve #3042 by adding native temporal aggregation support to t.rast.univar. This implementation allows users to compute univariate statistics over grouped time windows (granules) without the overhead of creating intermediate raster data via t.rast.aggregate.
Implementation Details
Parameter Addition: Added granularity and start options to the t.rast.univar CLI.
Library Logic: Updated the grass.temporal library (specifically print_gridded_dataset_univar_statistics) to handle map grouping based on the provided granularity.
Efficiency: The module now identifies all maps within a temporal granule and passes them as a comma-separated list to the r.univar backend, leveraging its native multi-map support.
Verification:
Added a comprehensive test class TestRasterUnivarGranularity to the existing testsuite.
Manually verified (see screenshot) that a 4-map STRDS correctly aggregates into 2-month granules with accurate mathematical results (Means of 15 and 35) and no additional raster creation.