Getting dictionary for each feature with their attribute values using PyQGIS

Question

I need to obtain, for each feature of a layer, a dictionary with the attribute names and their values using PyQGIS.

I can get all the attributes of the layer using:

from qgis.core import QgsProject
indiv = QgsProject.instance().mapLayersByName('Individuos')[0]
for feature in features:
    value = feature[field.name()]
    attrs = feature.attributes()
    print(attrs)

But what I need is to create a dictionary with field names as key and their value for each feature.

There's a bit of code between indiv= and for feature in features: that you've not shown. One line to get features from the layer and another to get field, or better still all the field names. — Spacedman, Sep 16 '20 at 10:09

score 16 · Accepted Answer · edited May 20 '23 at 08:14

The QgsJsonUtils class has exportAttributes method for getting attributes as a dict.

Solution 1:

Making a dictionary including feature "id" as key, attributes map as value:

{feature1.id: {attr1: value, attr2: value, ...},
 feature2.id: {attr1: value, attr2: value, ...},
 ...}

from qgis.core import QgsProject
layer = QgsProject.instance().mapLayersByName('LAYER_NAME')[0]
features_dict = {f.id(): QgsJsonUtils.exportAttributes(f) for f in layer.getFeatures()}

Solution 2:

Making a list including attributes map (dict) of features:

[{attr1: value, attr2: value, ...}, # feature 1
 {attr1: value, attr2: value, ...}, # feature 2
 ...]

from qgis.core import QgsProject
layer = QgsProject.instance().mapLayersByName('LAYER_NAME')[0]
features_list = [QgsJsonUtils.exportAttributes(f) for f in layer.getFeatures()]

Your solution 1 is perfect for what I'm looking. Thanks as always. — Raúl Casado, Sep 16 '20 at 11:11

score 11 · Answer 2 · edited May 20 '23 at 08:09

The snippet below should help you. It just prints a dictionary for each feature to the console, but you could do something else with the feature attribute dictionaries if you wanted.

from qgis.utils import iface
layer = iface.activeLayer()
def print_atts_dict(layer, feature):
    flds = [f for f in layer.fields()]
    atts = {}
    for f in flds:
        atts[f.name()] = feature[f.name()]
    print(atts)
for f in layer.getFeatures():
    print_atts_dict(layer, f)

score 5 · Answer 3 · edited May 20 '23 at 08:10

# get the fields and features:
fields = indiv.fields()
features = indiv.getFeatures()

# initialise an empty dict with each field name:
attdict = {}
for field in fields:
    attdict[field.name()] = []

# for each field in each feature, append the relevant field data to the dict item:
for feature in features:
  for field in fields:
    v = feature[field.name()]
    attdict[field.name()].append(v)

print(attdict)

That gives a dict that looks like this for some Ghana regions:

{'shapeName': ['Greater Accra', 'Central', 'Western', 'Eastern', 'Ashanti', 'Volta', 'Brong Ahafo', 'Northern', 'Upper West', 'Upper East'],
 'shapeISO': ['GH-AA', 'GH-CP', 'GH-WP', 'GH-EP', 'GH-AH', 'GH-TV', 'GH-BA', 'GH-NP', 'GH-UW', 'GH-UE'],
 'shapeID': ['GHA-ADM1-1590546715-B1', 'GHA-ADM1-1590546715-B2', 'GHA-ADM1-1590546715-B3', 'GHA-ADM1-1590546715-B4', 'GHA-ADM1-1590546715-B5', 'GHA-ADM1-1590546715-B6', 'GHA-ADM1-1590546715-B7', 'GHA-ADM1-1590546715-B8', 'GHA-ADM1-1590546715-B9', 'GHA-ADM1-1590546715-B10'],
 'shapeGroup': ['GHA', 'GHA', 'GHA', 'GHA', 'GHA', 'GHA', 'GHA', 'GHA', 'GHA', 'GHA'], 'shapeType': ['ADM1', 'ADM1', 'ADM1', 'ADM1', 'ADM1', 'ADM1', 'ADM1', 'ADM1', 'ADM1', 'ADM1']}

Which I think is what you are after.

score 5 · Answer 4 · edited May 20 '23 at 07:58

5

The easiest way is using the underdog __geo_interface__, that was defined by Sean Gillies at https://gist.github.com/sgillies/2217756:

layer = iface.activeLayer()
for feature in layer.getFeatures():
    attributes = feature.geo_interface["properties"]
    print(attributes)

References:

Adding __geo_interface__ to QGIS geometry and feature

edited May 20 '23 at 07:58

Taras

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answered Apr 23 '21 at 13:07

bugmenot123

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Taras · Answer 5 · 2023-07-15T09:31:20.997

Another solution utilizes the attributeMap() method of the QgsFeature class.

Returns the feature's attributes as a map of the field name to value.

from qgis.utils import iface
from PyQt5.QtCore import QDate
layer = iface.activeLayer()
for feat in layer.getFeatures():
    attributes = feat.attributeMap()
    attributes_ = {key : value if not isinstance(value, QDate) else value.toString("dd.MM.yyyy") for key, value in attributes.items()}
    print(feat.id(), attributes_)

That results into:

0 {'ColumnA': '1, Michigan Street, Michigan', 'ColumnB': 'Michigan Street', 'ColumnC': '01.05.2023', 'id': 1, 'integer': NULL, 'real': 15.15, 'string': 'Some Text', 'trouble': 'a'}
1 {'ColumnA': NULL, 'ColumnB': NULL, 'ColumnC': '30.04.2023', 'id': 2, 'integer': 100, 'real': NULL, 'string': 'Some Text', 'trouble': 'b'}
2 {'ColumnA': NULL, 'ColumnB': NULL, 'ColumnC': '02.05.2023', 'id': 3, 'integer': 100, 'real': 5.25, 'string': NULL, 'trouble': 'c'}
3 {'ColumnA': NULL, 'ColumnB': NULL, 'ColumnC': NULL, 'id': 4, 'integer': NULL, 'real': NULL, 'string': NULL, 'trouble': 'd'}
4 {'ColumnA': NULL, 'ColumnB': NULL, 'ColumnC': '03.05.2023', 'id': 5, 'integer': NULL, 'real': 10.1, 'string': 'Some Text', 'trouble': 'e'}

Note: There was performed one more additional step due to the type of an attribute - QDate() class which will appear as PyQt5.QtCore.QDate(2023, 5, 3) when one simply applies the feat.attributeMap().

Getting dictionary for each feature with their attribute values using PyQGIS

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