Class: QgsSizeScaleTransformer¶
-
class
qgis.core.
QgsSizeScaleTransformer
(type: QgsSizeScaleTransformer.ScaleType = QgsSizeScaleTransformer.Linear, minValue: float = 0, maxValue: float = 1, minSize: float = 0, maxSize: float = 1, nullSize: float = 0, exponent: float = 1)¶ Bases:
QgsPropertyTransformer
Constructor for QgsSizeScaleTransformer.
- Parameters
type (QgsSizeScaleTransformer.ScaleType = QgsSizeScaleTransformer.Linear) – scaling type
minValue (float = 0) – minimum expected value
maxValue (float = 1) – maximum expected value
minSize (float = 0) – minimum size to return
maxSize (float = 1) – maximum size to return
nullSize (float = 0) – size to return for null values
exponent (float = 1) – exponent for Exponential scaling method
QgsSizeScaleTransformer(
QgsSizeScaleTransformer
)QgsPropertyTransformer
subclass for scaling a value into a size according to various scaling methods.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
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.
- 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.
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