Class: QgsSizeScaleTransformer¶
- class qgis.core.QgsSizeScaleTransformer¶
Bases:
QgsPropertyTransformer
QgsPropertyTransformer
subclass for scaling a value into a size according to various scaling methods.QgsSizeScaleTransformer(type: QgsSizeScaleTransformer.ScaleType = QgsSizeScaleTransformer.Linear, minValue: float = 0, maxValue: float = 1, minSize: float = 0, maxSize: float = 1, nullSize: float = 0, exponent: float = 1) Constructor for QgsSizeScaleTransformer.
- Parameters:
type – scaling type
minValue – minimum expected value
maxValue – maximum expected value
minSize – minimum size to return
maxSize – maximum size to return
nullSize – size to return for null values
exponent – exponent for Exponential scaling method
QgsSizeScaleTransformer(
QgsSizeScaleTransformer
)Methods
- rtype:
QgsSizeScaleTransformer
Returns the exponent for an exponential expression.
Attempts to parse an expression into a corresponding QgsSizeScaleTransformer.
- param definition:
Returns the maximum calculated size.
Returns the minimum calculated size.
Returns the size value when an expression evaluates to NULL.
Sets the exponent for an exponential expression.
Sets the maximum calculated size.
Sets the minimum calculated size.
Sets the size value for when an expression evaluates to NULL.
Sets the size transformer's scaling type (the method used to calculate the size from a value).
Calculates the size corresponding to a specific value.
- param baseExpression:
- rtype:
Any
- param context:
Applies base class numeric transformations.
- rtype:
QgsPropertyTransformer.Type
Returns the size transformer's scaling type (the method used to calculate the size from a value).
Attributes
- Area = 1¶
- Exponential = 3¶
- Flannery = 2¶
- Linear = 0¶
- class ScaleType¶
Bases:
int
- clone(self) QgsSizeScaleTransformer ¶
- Return type:
- exponent(self) float ¶
Returns the exponent for an exponential expression.
See also
See also
- Return type:
float
- fromExpression(expression: str) Tuple[QgsSizeScaleTransformer, str, str] ¶
Attempts to parse an expression into a corresponding QgsSizeScaleTransformer.
- Parameters:
expression (str) – expression to parse
- Return type:
Tuple[
QgsSizeScaleTransformer
, str, str]- Returns:
corresponding
QgsSizeScaleTransformer
, orNone
if expression could notbaseExpression: 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.
be parsed to a size scale transformer.
- loadVariant(self, definition: Any) bool ¶
- Parameters:
definition (Any)
- Return type:
bool
- minSize(self) float ¶
Returns the minimum calculated size.
See also
See also
- Return type:
float
- nullSize(self) float ¶
Returns the size value when an expression evaluates to NULL.
See also
- Return type:
float
- setExponent(self, exponent: float)¶
Sets the exponent for an exponential expression.
- Parameters:
exponent (float) – exponent
See also
- setMaxSize(self, size: float)¶
Sets the maximum calculated size.
- Parameters:
size (float) – maximum size
See also
See also
- setMinSize(self, size: float)¶
Sets the minimum calculated size.
- Parameters:
size (float) – minimum size
See also
See also
- setNullSize(self, size: float)¶
Sets the size value for when an expression evaluates to NULL.
- Parameters:
size (float) – null size
See also
- setType(self, type: QgsSizeScaleTransformer.ScaleType)¶
Sets the size transformer’s scaling type (the method used to calculate the size from a value).
- Parameters:
type (QgsSizeScaleTransformer.ScaleType) – scale type
See also
- size(self, value: float) float ¶
Calculates the size corresponding to a specific value.
- Parameters:
value (float) – value to calculate size for
- Return type:
float
- Returns:
calculated size using size scale transformer’s parameters and type
- toExpression(self, baseExpression: str) str ¶
- Parameters:
baseExpression (str)
- Return type:
str
- toVariant(self) Any ¶
- Return type:
Any
- transform(self, context: QgsExpressionContext, value: Any) Any ¶
- Parameters:
context (QgsExpressionContext)
value (Any)
- Return type:
Any
- transformNumeric(self, input: float) float ¶
Applies base class numeric transformations. Derived classes should call this to transform an
input
numeric value before they apply any transform to the result. This applies any curve transforms which may exist on the transformer.
- transformerType(self) QgsPropertyTransformer.Type ¶
- Return type:
- type(self) QgsSizeScaleTransformer.ScaleType ¶
Returns the size transformer’s scaling type (the method used to calculate the size from a value).
See also
- Return type: