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QGis raster categories proportion per polygon

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3

1

I have a raster layer of landuse and a vector layer of areas of interest. I would like to calculate for each polygon (areas of interest) the proportion or number of cells of the raster for each category. I would like to get a table of areas in rows, raster categories in column and the number / proportion of cell for each combination.

I'm sure there is an easy way to do that but I couldn't find it. All I got was global statistics through Zonal Stats but I couldn't calculate per category.

qgis raster zonal-statistics

share|improve this question

edited Oct 13 '17 at 12:36

PolyGeo♦

53.9k1781245

asked Oct 13 '17 at 8:35

Victor CazalisVictor Cazalis

161

bumped to the homepage by Community♦ 2 days ago

This question has answers that may be good or bad; the system has marked it active so that they can be reviewed.

add a comment | 

3

1

I have a raster layer of landuse and a vector layer of areas of interest. I would like to calculate for each polygon (areas of interest) the proportion or number of cells of the raster for each category. I would like to get a table of areas in rows, raster categories in column and the number / proportion of cell for each combination.

I'm sure there is an easy way to do that but I couldn't find it. All I got was global statistics through Zonal Stats but I couldn't calculate per category.

qgis raster zonal-statistics

share|improve this question

edited Oct 13 '17 at 12:36

PolyGeo♦

53.9k1781245

asked Oct 13 '17 at 8:35

Victor CazalisVictor Cazalis

161

bumped to the homepage by Community♦ 2 days ago

This question has answers that may be good or bad; the system has marked it active so that they can be reviewed.

add a comment | 

I have a raster layer of landuse and a vector layer of areas of interest. I would like to calculate for each polygon (areas of interest) the proportion or number of cells of the raster for each category. I would like to get a table of areas in rows, raster categories in column and the number / proportion of cell for each combination.

I'm sure there is an easy way to do that but I couldn't find it. All I got was global statistics through Zonal Stats but I couldn't calculate per category.

qgis raster zonal-statistics

share|improve this question

edited Oct 13 '17 at 12:36

PolyGeo♦

53.9k1781245

asked Oct 13 '17 at 8:35

Victor CazalisVictor Cazalis

161

share|improve this question

edited Oct 13 '17 at 12:36

PolyGeo♦

53.9k1781245

asked Oct 13 '17 at 8:35

Victor CazalisVictor Cazalis

161

share|improve this question

edited Oct 13 '17 at 12:36

PolyGeo♦

53.9k1781245

asked Oct 13 '17 at 8:35

Victor CazalisVictor Cazalis

161

edited Oct 13 '17 at 12:36

PolyGeo♦

53.9k1781245

edited Oct 13 '17 at 12:36

PolyGeo♦

53.9k1781245

asked Oct 13 '17 at 8:35

Victor CazalisVictor Cazalis

161

asked Oct 13 '17 at 8:35

Victor CazalisVictor Cazalis

161

1 Answer
1

active

oldest

votes

0

I had a very similar situation, and came across this answer

Essentially, you have to create an indicator gird of 0s and 1s, for each of your landuse types. And then use a combination of Count and Sum from the Zonal Statistics plugin. Count will give total number of raster cells in each polygon, and Sum will give number of cells = 1. You can then determine proportion of cover within each polygon. Maybe a bit cumbersome if you have a lot of landuse types, but straightforward.

---

Edit

As of QGIS 3.2 there is a Zonal Histogram tool which should perform this automatically, saving the need to create multiple indicator grids.

share|improve this answer

edited Mar 1 at 8:30

answered Mar 1 at 8:18

EcologyTomEcologyTom

19612

add a comment | 

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0

I had a very similar situation, and came across this answer

Essentially, you have to create an indicator gird of 0s and 1s, for each of your landuse types. And then use a combination of Count and Sum from the Zonal Statistics plugin. Count will give total number of raster cells in each polygon, and Sum will give number of cells = 1. You can then determine proportion of cover within each polygon. Maybe a bit cumbersome if you have a lot of landuse types, but straightforward.

---

Edit

As of QGIS 3.2 there is a Zonal Histogram tool which should perform this automatically, saving the need to create multiple indicator grids.

share|improve this answer

edited Mar 1 at 8:30

answered Mar 1 at 8:18

EcologyTomEcologyTom

19612

add a comment | 

0

I had a very similar situation, and came across this answer

Essentially, you have to create an indicator gird of 0s and 1s, for each of your landuse types. And then use a combination of Count and Sum from the Zonal Statistics plugin. Count will give total number of raster cells in each polygon, and Sum will give number of cells = 1. You can then determine proportion of cover within each polygon. Maybe a bit cumbersome if you have a lot of landuse types, but straightforward.

---

Edit

As of QGIS 3.2 there is a Zonal Histogram tool which should perform this automatically, saving the need to create multiple indicator grids.

share|improve this answer

edited Mar 1 at 8:30

answered Mar 1 at 8:18

EcologyTomEcologyTom

19612

add a comment | 

I had a very similar situation, and came across this answer

Essentially, you have to create an indicator gird of 0s and 1s, for each of your landuse types. And then use a combination of Count and Sum from the Zonal Statistics plugin. Count will give total number of raster cells in each polygon, and Sum will give number of cells = 1. You can then determine proportion of cover within each polygon. Maybe a bit cumbersome if you have a lot of landuse types, but straightforward.

---

Edit

As of QGIS 3.2 there is a Zonal Histogram tool which should perform this automatically, saving the need to create multiple indicator grids.

share|improve this answer

edited Mar 1 at 8:30

answered Mar 1 at 8:18

EcologyTomEcologyTom

19612

share|improve this answer

edited Mar 1 at 8:30

answered Mar 1 at 8:18

EcologyTomEcologyTom

19612

answered Mar 1 at 8:18

EcologyTomEcologyTom

19612

answered Mar 1 at 8:18

EcologyTomEcologyTom

19612