Class: QgsGenericNumericTransformer

class qgis.core.QgsGenericNumericTransformer(minValue: float = 0, maxValue: float = 1, minOutput: float = 0, maxOutput: float = 1, nullOutput: float = 0, exponent: float = 1)

Bases: qgis._core.QgsPropertyTransformer

Constructor for QgsGenericNumericTransformer.

Parameters
  • minValue – minimum expected input value

  • maxValue – maximum expected input value

  • minOutput – minimum value to return

  • maxOutput – maximum value to return

  • nullOutput – value to return for null inputs

  • exponent – optional exponential for non-linear scaling

QgsGenericNumericTransformer(QgsGenericNumericTransformer)

QgsPropertyTransformer subclass for scaling an input numeric value into an output numeric value.

New in version 3.0: Enums

Methods

clone

exponent

Returns the exponent for an exponential expression.

fromExpression

Attempts to parse an expression into a corresponding QgsSizeScaleTransformer.

loadVariant

maxOutputValue

Returns the maximum calculated size.

minOutputValue

Returns the minimum calculated size.

nullOutputValue

Returns the size value when an expression evaluates to NULL.

setExponent

Sets the exponent for an exponential expression.

setMaxOutputValue

Sets the maximum calculated size.

setMinOutputValue

Sets the minimum calculated size.

setNullOutputValue

Sets the size value for when an expression evaluates to NULL.

toExpression

toVariant

transform

transformNumeric

transformerType

value

Calculates the size corresponding to a specific input value.

Signals

Attributes

clone(self) → QgsGenericNumericTransformer
exponent(self) → float

Returns the exponent for an exponential expression.

See also

setExponent()

fromExpression(expression: str) → Tuple[QgsGenericNumericTransformer, str, str]

Attempts to parse an expression into a corresponding QgsSizeScaleTransformer.

Parameters
  • expression – expression to parse

  • baseExpression – will be set to the component of the source expression which is used to calculate the input to the property transformer. This will be set to an empty string if a field reference is the transformer input.

  • fieldName – will be set to a field name which is used to calculate the input to the property transformer. This will be set to an empty string if an expression is the transformer input.

Returns

corresponding QgsSizeScaleTransformer, or None if expression could not be parsed to a size scale transformer.

loadVariant(self, definition: Any) → bool
maxOutputValue(self) → float

Returns the maximum calculated size.

See also

minOutputValue()

minOutputValue(self) → float

Returns the minimum calculated size.

See also

maxOutputValue()

nullOutputValue(self) → float

Returns the size value when an expression evaluates to NULL.

setExponent(self, exponent: float)

Sets the exponent for an exponential expression.

Parameters

exponent – exponent

See also

exponent()

setMaxOutputValue(self, size: float)

Sets the maximum calculated size.

Parameters

size – maximum size

See also

maxOutputValue()

setMinOutputValue(self, size: float)

Sets the minimum calculated size.

Parameters

size – minimum size

See also

minOutputValue()

setNullOutputValue(self, size: float)

Sets the size value for when an expression evaluates to NULL.

Parameters

size – null size

toExpression(self, baseExpression: str) → str
toVariant(self) → Any
transform(self, context: QgsExpressionContext, value: Any) → Any
transformNumeric()
transformerType(self) → QgsPropertyTransformer.Type
value(self, input: float) → float

Calculates the size corresponding to a specific input value.

Returns

calculated size using size scale transformer’s parameters and type