Continuous & Categorical¶

Pick the mode that matches your raster. The dialog exposes them as two tabs, and the Processing Toolbox as two algorithms.

Why the split matters

The mean of land-cover codes {1=water, 2=forest, 5=urban} is a meaningless number. Categorical mode summarises the class composition instead — and a raster with more than 65,536 distinct values is rejected as "actually continuous".

Continuous¶

For measured quantities where averaging is meaningful (elevation, temperature, reflectance, NDVI).

Statistics: count, nodata, min, max, sum, mean, stddev (population standard deviation, divided by n, matching QGIS's own tool).

Long layout¶

One row per polygon and band:

fid,polygon_id,polygon_name,band_index,band_name,count,mean,stddev
1,101,North field,1,ndvi,4210,0.62,0.11
2,101,North field,2,ndvi_may,4210,0.58,0.09
3,102,South field,1,ndvi,3980,0.71,0.08

Wide layout¶

One row per polygon; each band's stats become columns prefixed with that band's own name:

fid,polygon_id,polygon_name,ndvi_mean,ndvi_stddev,ndvi_may_mean,ndvi_may_stddev
1,101,North field,0.62,0.11,0.58,0.09
2,102,South field,0.71,0.08,0.66,0.07

Categorical¶

For discrete class codes (land cover, soil type, zoning). Values are read as integer class codes (floating-point rasters are rounded to the nearest integer).

Statistics: majority (most common class), minority (least common class), variety (distinct class count), plus count and nodata. Ties on majority/minority resolve to the lowest class code.

Summary layout¶

One row per polygon and band:

fid,polygon_id,polygon_name,band_index,band_name,majority,minority,variety,count
1,101,North field,1,landcover,3,4,4,16
2,102,South field,1,landcover,2,1,3,16

Class breakdown layout¶

One row per polygon, band and class, with the pixel count and fraction:

fid,polygon_id,polygon_name,band_index,band_name,class,pixel_count,fraction
1,101,North field,1,landcover,1,4,0.250
2,101,North field,1,landcover,2,4,0.250
3,101,North field,1,landcover,3,5,0.312
4,101,North field,1,landcover,4,3,0.188

Class counts (wide) layout¶

One row per polygon and band, with one class_<code> column of pixel counts:

fid,polygon_id,polygon_name,band_index,band_name,class_1,class_2,class_3,class_4
1,101,North field,1,landcover,4,4,5,3
2,102,South field,1,landcover,7,4,1,4

Shared columns

The class columns are the union of classes across all zones, so every row shares the same columns — a class absent from a zone is simply 0.