Docs for ‘QGIS testing’. Visit http://docs.qgis.org/2.18 for QGIS 2.18 docs and translations.

Vector selection

Extract by attribute

Description

Creates new vector layer that only contains certain features from an input layer. The criteria for adding features to the resulting layer is defined based on the values of an attribute from the input layer.

Parameters

Input Layer [vector: any]
<put parameter description here>
Selection attribute [tablefield: any]
<put parameter description here>
Operator [selection]

<put parameter description here>

Options:

  • 0 — =
  • 1 — !=
  • 2 — >
  • 3 — >=
  • 4 — <
  • 5 — <=
  • 6 — begins with
  • 7 — contains

Default: 0

Value [string]

<put parameter description here>

Default: (not set)

Outputs

Extracted (attribute) [vector]
<put output description here>

Console usage

processing.runalg('qgis:extractbyattribute', input, field, operator, value, output)

See also

Extract by location

Description

Creates new vector layer that only contains certain features from an input layer. The criteria for adding features to the resulting layer is defined based on the spatial relationship between each feature and the features in an additional layer.

Parameters

Layer to select from [vector: any]
<put parameter description here>
Additional layer (intersection layer) [vector: any]
<put parameter description here>
Predicate [array of Unicode strings]

Condition for the selection. Array of one or more of the following predicates:

  • disjoint
  • intersects
  • contains
  • equals
  • touches
  • overlaps
  • within
  • crosses

For console usage the predicates must be defined as an array of Unicode strings, eg. [u’intersects’,u’contains’]

Precision [number]
<put parameter description here>

Outputs

Extracted (location)
<put output description here>

Console usage

processing.runalg('qgis:extractbylocation', input, intersect, predicates, precision, output)

See also

Random extract

Description

Takes a vector layer and generates a new one that contains only a subset of the features in the input layer. The subset is defined randomly, using a percentage or count value to define the total number of features in the subset.

Parameters

Input layer [vector: any]
<put parameter description here>
Method [selection]

<put parameter description here>

Options:

  • 0 — Number of selected features
  • 1 — Percentage of selected features

Default: 0

Number/percentage of selected features [number]

<put parameter description here>

Default: 10

Outputs

Extracted (random) [vector]
<put output description here>

Console usage

processing.runalg('qgis:randomextract', input, method, number, output)

See also

Random extract within subsets

Description

Takes a vector layer and generates a new one that contains only a subset of the features in the input layer. The subset is defined randomly, using a percentage or count value to define the total number of features in the subset. The percentage/count value is not applied to the whole layer, but instead to each category. Categories are defined according to a given attribute, which is also specified as an input parameter for the algorithm.

Parameters

Input layer [vector: any]
<put parameter description here>
ID Field [tablefield: any]
<put parameter description here>
Method [selection]

<put parameter description here>

Options:

  • 0 — Number of selected features
  • 1 — Percentage of selected features

Default: 0

Number/percentage of selected features [number]

<put parameter description here>

Default: 10

Outputs

``Extracted (random stratified) [vector]
<put output description here>

Console usage

processing.runalg('qgis:randomextractwithinsubsets', input, field, method, number, output)

See also

Random selection

Description

Takes a vector layer and selects a subset of its features. No new layer is generated by this algorithm. The subset is defined randomly, using a percentage or count value to define the total number of features in the subset.

Parameters

Input layer [vector: any]
<put parameter description here>
Method [selection]

<put parameter description here>

Options:

  • 0 — Number of selected features
  • 1 — Percentage of selected features

Default: 0

Number/percentage of selected features [number]

<put parameter description here>

Default: 10

Outputs

Same vector input layer with selected features

Console usage

processing.runalg('qgis:randomselection', input, method, number)

See also

Random selection within subsets

Description

Takes a vector layer and selects a subset of its features. No new layer is generated by this algorithm. The subset is defined randomly, using a percentage or count value to define the total number of features in the subset. The percentage/count value is not applied to the whole layer, but instead to each category. Categories are defined according to a given attribute, which is also specified as an input parameter for the algorithm.

Parameters

Input layer [vector: any]
<put parameter description here>
ID Field [tablefield: any]
<put parameter description here>
Method [selection]

<put parameter description here>

Options:

  • 0 — Number of selected features
  • 1 — Percentage of selected features

Default: 0

Number/percentage of selected features [number]

<put parameter description here>

Default: 10

Outputs

Same vector input layer with selected features

Console usage

processing.runalg('qgis:randomselectionwithinsubsets', input, field, method, number)

See also

Remove null geometries

Description

Removes any features which do not have a geometry from a vector layer. All other features will be copied unchanged.

Parameters

Input layer [vector: any]
<put parameter description here>

Outputs

Selection [vector]
<put output description here>

Console usage

processing.runalg('qgis:removenullgeometries', input, output)

See also

Select by attribute

Description

Creates a selection in a vector layer. The criteria for selected features is defined based on the values of an attribute from the input layer.

Parameters

Input Layer [vector: any]
Layer to process.
Selection attribute [tablefield: any]
Field on which perform the selection.
Operator [selection]

Comparison operator.

Options:

  • 0 — =
  • 1 — !=
  • 2 — >
  • 3 — >=
  • 4 — <
  • 5 — <=
  • 6 — begins with
  • 7 — contains

Default: 0

Value [string]

Value to compare.

Default: (not set)

Outputs

Same vector input layer with selected features

Console usage

processing.runalg('qgis:selectbyattribute', input, field, operator, value)

See also

Select by attribute sum

Description

<put algorithm description here>

Parameters

Input Layer [vector: any]
<put parameter description here>
Selection attribute [tablefield: number]
<put parameter description here>
Value [number]

Value to compare.

Default: 0

Outputs

Output [vector]
<put parameter description here>

Console usage

processing.runalg('qgis:selectbyattributesum', input, field, value)

See also

Select by expression

Description

Creates a selection in a vector layer. The criteria for selecting features is based on a QGIS expression.

Parameters

Input Layer [vector: any]
<put parameter description here>
Expression [string]

<put parameter description here>

Default: (not set)

Modify current selection by [selection]

<put parameter description here>

Options:

  • 0 — creating new selection
  • 1 — adding to current selection
  • 2 — removing from current selection
  • 3 — selecting within current selection

Default: 0

Outputs

Same vector input layer with selected features

Console usage

processing.runalg('qgis:selectbyexpression', layername, expression, method)

See also

Select by location

Description

Creates a selection in a vector layer. The criteria for selecting features is based on the spatial relationship between each feature and the features in an additional layer.

Parameters

Layer to select from [vector: any]
<put parameter description here>
Additional layer (intersection layer) [vector: any]
<put parameter description here>
Predicate [array of Unicode strings]

Condition for the selection. Array of one or more of the following predicates:

  • disjoint
  • intersects
  • contains
  • equals
  • touches
  • overlaps
  • within
  • crosses

For console usage the predicates must be defined as an array of Unicode strings, eg. [u’intersects’,u’contains’]

Modify current selection by [selection]

<put parameter description here>

Options:

  • 0 — creating new selection
  • 1 — adding to current selection
  • 2 — removing from current selection

Default: 0

Outputs

Same vector input layer with selected features

Console usage

processing.runalg('qgis:selectbylocation', input, intersect, predicate, precision, method)

See also