Class: QgsHistogram¶
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class
qgis.core.
QgsHistogram
¶ Bases:
sip.wrapper
Constructor for QgsHistogram.
QgsHistogram(QgsHistogram)
Calculator for a numeric histogram from a list of values.
New in version 2.9: Enums
Methods
Returns a list of edges for the histogram for a specified number of bins.
Returns the calculated list of the counts for the histogram bins.
Calculates the optimal bin width using the Freedman-Diaconis rule.
Returns the optimal number of bins for the source values, calculated using the Freedman-Diaconis rule.
Assigns numeric source values for the histogram.
Signals
Attributes
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binEdges
(self, bins: int) → List[float]¶ Returns a list of edges for the histogram for a specified number of bins. This list will be length bins + 1, as both the first and last value are also included.
- Parameters
bins – number of bins
- Returns
list of bin edges
Note
values must first be specified using setValues()
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counts
(self, bins: int) → List[int]¶ Returns the calculated list of the counts for the histogram bins.
- Parameters
bins – number of histogram bins
- Returns
list of histogram counts
Note
values must first be specified using setValues()
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optimalBinWidth
(self) → float¶ Calculates the optimal bin width using the Freedman-Diaconis rule. Bins widths are determined by the inter-quartile range of values and the number of values.
- Returns
optimal width for bins
See also
Note
values must first be specified using setValues()
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optimalNumberBins
(self) → int¶ Returns the optimal number of bins for the source values, calculated using the Freedman-Diaconis rule. The number of bins are determined by the inter-quartile range of values and the number of values.
- Returns
optimal number of bins
See also
Note
values must first be specified using setValues()
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setValues
(self, values: Iterable[float])¶ Assigns numeric source values for the histogram.
- Parameters
values – list of doubles
setValues(self, layer: QgsVectorLayer, fieldOrExpression: str, feedback: QgsFeedback = None) -> bool Assigns numeric source values for the histogram from a vector layer’s field or as the result of an expression.
- Parameters
layer – vector layer
fieldOrExpression – field name or expression to be evaluated
feedback – optional feedback object to allow cancellation of calculation
- Returns
True
if values were successfully set
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