Count of the different combination of two attributes in QGIS?

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I've been trying in vain to use the field calculator in QGIS 2.8 to count the combinations of two attributes in two separate columns.

First column is called "Alds_klass" and second is called "bygn_klass". I want to count the different combinations of the two columns, not the sum, but the number of each combination.

enter image description here

edited Aug 7 at 7:13

Jochen Schwarze

5,42021249

asked Aug 6 at 11:59

Felipe_H81

192

add a commentÂ |Â

up vote
3
down vote

favorite

I've been trying in vain to use the field calculator in QGIS 2.8 to count the combinations of two attributes in two separate columns.

First column is called "Alds_klass" and second is called "bygn_klass". I want to count the different combinations of the two columns, not the sum, but the number of each combination.

enter image description here

edited Aug 7 at 7:13

Jochen Schwarze

5,42021249

asked Aug 6 at 11:59

Felipe_H81

192

add a commentÂ |Â

up vote
3
down vote

favorite

I've been trying in vain to use the field calculator in QGIS 2.8 to count the combinations of two attributes in two separate columns.

First column is called "Alds_klass" and second is called "bygn_klass". I want to count the different combinations of the two columns, not the sum, but the number of each combination.

enter image description here

edited Aug 7 at 7:13

Jochen Schwarze

5,42021249

asked Aug 6 at 11:59

Felipe_H81

192

I've been trying in vain to use the field calculator in QGIS 2.8 to count the combinations of two attributes in two separate columns.

First column is called "Alds_klass" and second is called "bygn_klass". I want to count the different combinations of the two columns, not the sum, but the number of each combination.

enter image description here

edited Aug 7 at 7:13

Jochen Schwarze

5,42021249

asked Aug 6 at 11:59

Felipe_H81

192

edited Aug 7 at 7:13

Jochen Schwarze

5,42021249

edited Aug 7 at 7:13

Jochen Schwarze

5,42021249

edited Aug 7 at 7:13

Jochen Schwarze

5,42021249

asked Aug 6 at 11:59

Felipe_H81

192

asked Aug 6 at 11:59

Felipe_H81

192

asked Aug 6 at 11:59

Felipe_H81

192

add a commentÂ |Â

5 Answers
5

active

oldest

votes

up vote
6
down vote

If you're ready NOT to use the field calculator i would create a virtual layer based on the following query (to adapt) :

select count(*) as tot, col_a, col_b from my_table
group by col_a, col_b
order by tot desc

Which would be "dynamic" ...

(implies to use a newer QGIS version...)

answered Aug 6 at 13:31

snaileater

1,243512

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up vote
3
down vote

You can use the tool "Statistics by categories" (in the processing toolbox in QGIS 3.2)

enter image description here

answered Aug 6 at 14:45

Volta

567211

It worked. Thanks Volta
â€“Â Felipe_H81
Aug 7 at 11:54

add a commentÂ |Â

up vote
0
down vote

Create a new column and fill it with a case when or if clause looping over all possible values. Assign each combination a different letter of the alphabet, and then do a statistical analysis of the new column.

Or just load it into a database.

answered Aug 6 at 12:47

Erik

1,38611

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up vote
0
down vote

If you want to populate Count_Al_b with the total count of combinations Alds_class+bygn_class you can use collections.Counter:

...where elements are stored as dictionary keys and their counts are
stored as dictionary values.

print 'start'
from qgis.core import *
import qgis.utils
from qgis.core import QgsVectorLayer
from collections import Counter

alds = "Alds_klass"
bygn = "bygn_klass"
totcount = "Count_Al_b"
datafile = '/media/bera/my_03.shp' #Change

layer = QgsVectorLayer(datafile, 'temp', 'ogr')
c = Counter([(f[alds],f[bygn]) for f in layer.getFeatures()])

layer.startEditing()
it = layer.getFeatures()
for feat in it:
 layer.changeAttributeValue(feat.id(),layer.fieldNameIndex(totcount),c[(feat[alds],feat[bygn])])
 #layer.fields().indexFromName(totcount) python 3/QGIS 3
layer.commitChanges()
print 'stop'

Example:
enter image description here

edited Aug 7 at 8:33

answered Aug 7 at 8:27

BERA

10.5k31435

add a commentÂ |Â

up vote
0
down vote

I would use the field calculator to create a virtual field containing the concatenation (i.e. combination) of your two fields, like this:

enter image description here

The underscore '_' ist just for better readabilty and does not affect the result.

Then use the 'Show statistical summary' button (the button with the big sigma):

enter image description here

Herein select your layer and the virtual field you just created, and under Count (distinct) you will find the count of your columns combinations:

enter image description here

The virtual field and the tool do dynamically refresh when data changes.

edited Aug 8 at 7:52

answered Aug 7 at 7:03

Jochen Schwarze

5,42021249

add a commentÂ |Â

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5 Answers
5

active

oldest

votes

5 Answers
5

active

oldest

votes

up vote
6
down vote

If you're ready NOT to use the field calculator i would create a virtual layer based on the following query (to adapt) :

select count(*) as tot, col_a, col_b from my_table
group by col_a, col_b
order by tot desc

Which would be "dynamic" ...

(implies to use a newer QGIS version...)

answered Aug 6 at 13:31

snaileater

1,243512

add a commentÂ |Â

up vote
6
down vote

If you're ready NOT to use the field calculator i would create a virtual layer based on the following query (to adapt) :

select count(*) as tot, col_a, col_b from my_table
group by col_a, col_b
order by tot desc

Which would be "dynamic" ...

(implies to use a newer QGIS version...)

answered Aug 6 at 13:31

snaileater

1,243512

add a commentÂ |Â

up vote
6
down vote

If you're ready NOT to use the field calculator i would create a virtual layer based on the following query (to adapt) :

select count(*) as tot, col_a, col_b from my_table
group by col_a, col_b
order by tot desc

Which would be "dynamic" ...

(implies to use a newer QGIS version...)

answered Aug 6 at 13:31

snaileater

1,243512

If you're ready NOT to use the field calculator i would create a virtual layer based on the following query (to adapt) :

select count(*) as tot, col_a, col_b from my_table
group by col_a, col_b
order by tot desc

Which would be "dynamic" ...

(implies to use a newer QGIS version...)

answered Aug 6 at 13:31

snaileater

1,243512

answered Aug 6 at 13:31

snaileater

1,243512

answered Aug 6 at 13:31

snaileater

1,243512

answered Aug 6 at 13:31

snaileater

1,243512

add a commentÂ |Â

up vote
3
down vote

You can use the tool "Statistics by categories" (in the processing toolbox in QGIS 3.2)

enter image description here

answered Aug 6 at 14:45

Volta

567211

It worked. Thanks Volta
â€“Â Felipe_H81
Aug 7 at 11:54

add a commentÂ |Â

up vote
3
down vote

You can use the tool "Statistics by categories" (in the processing toolbox in QGIS 3.2)

enter image description here

answered Aug 6 at 14:45

Volta

567211

It worked. Thanks Volta
â€“Â Felipe_H81
Aug 7 at 11:54

add a commentÂ |Â

up vote
3
down vote

You can use the tool "Statistics by categories" (in the processing toolbox in QGIS 3.2)

enter image description here

answered Aug 6 at 14:45

Volta

567211

You can use the tool "Statistics by categories" (in the processing toolbox in QGIS 3.2)

enter image description here

answered Aug 6 at 14:45

Volta

567211

answered Aug 6 at 14:45

Volta

567211

answered Aug 6 at 14:45

Volta

567211

answered Aug 6 at 14:45

Volta

567211

It worked. Thanks Volta
â€“Â Felipe_H81
Aug 7 at 11:54

add a commentÂ |Â

It worked. Thanks Volta
â€“Â Felipe_H81
Aug 7 at 11:54

It worked. Thanks Volta
â€“Â Felipe_H81
Aug 7 at 11:54

add a commentÂ |Â

up vote
0
down vote

Or just load it into a database.

answered Aug 6 at 12:47

Erik

1,38611

add a commentÂ |Â

up vote
0
down vote

Or just load it into a database.

answered Aug 6 at 12:47

Erik

1,38611

add a commentÂ |Â

up vote
0
down vote

Or just load it into a database.

answered Aug 6 at 12:47

Erik

1,38611

Or just load it into a database.

answered Aug 6 at 12:47

Erik

1,38611

answered Aug 6 at 12:47

Erik

1,38611

answered Aug 6 at 12:47

Erik

1,38611

answered Aug 6 at 12:47

Erik

1,38611

add a commentÂ |Â

up vote
0
down vote

If you want to populate Count_Al_b with the total count of combinations Alds_class+bygn_class you can use collections.Counter:

...where elements are stored as dictionary keys and their counts are
stored as dictionary values.

print 'start'
from qgis.core import *
import qgis.utils
from qgis.core import QgsVectorLayer
from collections import Counter

alds = "Alds_klass"
bygn = "bygn_klass"
totcount = "Count_Al_b"
datafile = '/media/bera/my_03.shp' #Change

layer = QgsVectorLayer(datafile, 'temp', 'ogr')
c = Counter([(f[alds],f[bygn]) for f in layer.getFeatures()])

layer.startEditing()
it = layer.getFeatures()
for feat in it:
 layer.changeAttributeValue(feat.id(),layer.fieldNameIndex(totcount),c[(feat[alds],feat[bygn])])
 #layer.fields().indexFromName(totcount) python 3/QGIS 3
layer.commitChanges()
print 'stop'

Example:
enter image description here

edited Aug 7 at 8:33

answered Aug 7 at 8:27

BERA

10.5k31435

add a commentÂ |Â

up vote
0
down vote

If you want to populate Count_Al_b with the total count of combinations Alds_class+bygn_class you can use collections.Counter:

...where elements are stored as dictionary keys and their counts are
stored as dictionary values.

print 'start'
from qgis.core import *
import qgis.utils
from qgis.core import QgsVectorLayer
from collections import Counter

alds = "Alds_klass"
bygn = "bygn_klass"
totcount = "Count_Al_b"
datafile = '/media/bera/my_03.shp' #Change

layer = QgsVectorLayer(datafile, 'temp', 'ogr')
c = Counter([(f[alds],f[bygn]) for f in layer.getFeatures()])

layer.startEditing()
it = layer.getFeatures()
for feat in it:
 layer.changeAttributeValue(feat.id(),layer.fieldNameIndex(totcount),c[(feat[alds],feat[bygn])])
 #layer.fields().indexFromName(totcount) python 3/QGIS 3
layer.commitChanges()
print 'stop'

Example:
enter image description here

edited Aug 7 at 8:33

answered Aug 7 at 8:27

BERA

10.5k31435

add a commentÂ |Â

up vote
0
down vote

If you want to populate Count_Al_b with the total count of combinations Alds_class+bygn_class you can use collections.Counter:

...where elements are stored as dictionary keys and their counts are
stored as dictionary values.

print 'start'
from qgis.core import *
import qgis.utils
from qgis.core import QgsVectorLayer
from collections import Counter

alds = "Alds_klass"
bygn = "bygn_klass"
totcount = "Count_Al_b"
datafile = '/media/bera/my_03.shp' #Change

layer = QgsVectorLayer(datafile, 'temp', 'ogr')
c = Counter([(f[alds],f[bygn]) for f in layer.getFeatures()])

layer.startEditing()
it = layer.getFeatures()
for feat in it:
 layer.changeAttributeValue(feat.id(),layer.fieldNameIndex(totcount),c[(feat[alds],feat[bygn])])
 #layer.fields().indexFromName(totcount) python 3/QGIS 3
layer.commitChanges()
print 'stop'

Example:
enter image description here

edited Aug 7 at 8:33

answered Aug 7 at 8:27

BERA

10.5k31435

If you want to populate Count_Al_b with the total count of combinations Alds_class+bygn_class you can use collections.Counter:

...where elements are stored as dictionary keys and their counts are
stored as dictionary values.

print 'start'
from qgis.core import *
import qgis.utils
from qgis.core import QgsVectorLayer
from collections import Counter

alds = "Alds_klass"
bygn = "bygn_klass"
totcount = "Count_Al_b"
datafile = '/media/bera/my_03.shp' #Change

layer = QgsVectorLayer(datafile, 'temp', 'ogr')
c = Counter([(f[alds],f[bygn]) for f in layer.getFeatures()])

layer.startEditing()
it = layer.getFeatures()
for feat in it:
 layer.changeAttributeValue(feat.id(),layer.fieldNameIndex(totcount),c[(feat[alds],feat[bygn])])
 #layer.fields().indexFromName(totcount) python 3/QGIS 3
layer.commitChanges()
print 'stop'

Example:
enter image description here

edited Aug 7 at 8:33

answered Aug 7 at 8:27

BERA

10.5k31435

edited Aug 7 at 8:33

answered Aug 7 at 8:27

BERA

10.5k31435

answered Aug 7 at 8:27

BERA

10.5k31435

answered Aug 7 at 8:27

BERA

10.5k31435

add a commentÂ |Â

up vote
0
down vote

I would use the field calculator to create a virtual field containing the concatenation (i.e. combination) of your two fields, like this:

enter image description here

The underscore '_' ist just for better readabilty and does not affect the result.

Then use the 'Show statistical summary' button (the button with the big sigma):

enter image description here

Herein select your layer and the virtual field you just created, and under Count (distinct) you will find the count of your columns combinations:

enter image description here

The virtual field and the tool do dynamically refresh when data changes.

edited Aug 8 at 7:52

answered Aug 7 at 7:03

Jochen Schwarze

5,42021249

add a commentÂ |Â

up vote
0
down vote

I would use the field calculator to create a virtual field containing the concatenation (i.e. combination) of your two fields, like this:

enter image description here

The underscore '_' ist just for better readabilty and does not affect the result.

Then use the 'Show statistical summary' button (the button with the big sigma):

enter image description here

Herein select your layer and the virtual field you just created, and under Count (distinct) you will find the count of your columns combinations:

enter image description here

The virtual field and the tool do dynamically refresh when data changes.

edited Aug 8 at 7:52

answered Aug 7 at 7:03

Jochen Schwarze

5,42021249

add a commentÂ |Â

up vote
0
down vote

I would use the field calculator to create a virtual field containing the concatenation (i.e. combination) of your two fields, like this:

enter image description here

The underscore '_' ist just for better readabilty and does not affect the result.

Then use the 'Show statistical summary' button (the button with the big sigma):

enter image description here

Herein select your layer and the virtual field you just created, and under Count (distinct) you will find the count of your columns combinations:

enter image description here

The virtual field and the tool do dynamically refresh when data changes.

edited Aug 8 at 7:52

answered Aug 7 at 7:03

Jochen Schwarze

5,42021249

I would use the field calculator to create a virtual field containing the concatenation (i.e. combination) of your two fields, like this:

enter image description here

The underscore '_' ist just for better readabilty and does not affect the result.

Then use the 'Show statistical summary' button (the button with the big sigma):

enter image description here

Herein select your layer and the virtual field you just created, and under Count (distinct) you will find the count of your columns combinations:

enter image description here

The virtual field and the tool do dynamically refresh when data changes.

edited Aug 8 at 7:52

answered Aug 7 at 7:03

Jochen Schwarze

5,42021249

edited Aug 8 at 7:52

answered Aug 7 at 7:03

Jochen Schwarze

5,42021249

answered Aug 7 at 7:03

Jochen Schwarze

5,42021249

answered Aug 7 at 7:03

Jochen Schwarze

5,42021249

add a commentÂ |Â

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