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

• 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

setMinOutputValue()

See also

maxOutputValue()

nullOutputValue(self) → float

Returns the size value when an expression evaluates to NULL.

See also

setNullOutputValue()

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()

See also

setMinOutputValue()

setMinOutputValue(self, size: float)

Sets the minimum calculated size.

Parameters

size – minimum size

See also

minOutputValue()

See also

setMaxOutputValue()

setNullOutputValue(self, size: float)

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

Parameters

size – null size

See also

nullOutputValue()

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