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: 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
  • 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
  • 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.

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