From 06e2c6ebd8848f5b3662c528af53e63f11c7fee6 Mon Sep 17 00:00:00 2001 From: =?UTF-8?q?Jean-Fran=C3=A7ois=20Bourdon?= <32580398+jfbourdon@users.noreply.github.com> Date: Thu, 13 Jan 2022 07:46:03 -0500 Subject: [PATCH] v.rast.stats: note about vector overlap limitation (#1730) * explain behaviour and incomplete stats if areas have multiple categories in the selected layer Co-authored-by: Markus Metz <33666869+metzm@users.noreply.github.com> --- scripts/v.rast.stats/v.rast.stats.html | 10 ++++++++++ 1 file changed, 10 insertions(+) diff --git a/scripts/v.rast.stats/v.rast.stats.html b/scripts/v.rast.stats/v.rast.stats.html index 835ebda0c98..641e58e4143 100644 --- a/scripts/v.rast.stats/v.rast.stats.html +++ b/scripts/v.rast.stats/v.rast.stats.html @@ -31,6 +31,16 @@

NOTES

will be chopped off.

If a MASK is present, it will be restored after the script finished. The script changes temporarily to the resolution of the given raster map. +

If an area has several categories in the selected layer (equivalent +to overlapping polygons in Simple Features), only one category will be +kept during the rasterization process. Statistics for the skipped +categories will thus be partial. +

+For example, if there are three areas: area 1 with cat 1, area 2 with +cat 2, area 3 with cats 1, 2. Only one category value of area 3 will be +used for rasterization, the other category value will be skipped. Thus +statistics for the used category value will be complete, while +statistics for the skipped category value will be incomplete.

Large amounts of system memory can be used when extended statistics (first_quartile,median,third_quartile,percentile ) are being requested