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67 lines
2.2 KiB
Plaintext
67 lines
2.2 KiB
Plaintext
/** \ingroup core
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* \class QgsHistogram
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* \brief Calculator for a numeric histogram from a list of values.
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*
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* \note Added in version 2.9
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*/
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class QgsHistogram
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{
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%TypeHeaderCode
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#include "qgshistogram.h"
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%End
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public:
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QgsHistogram();
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virtual ~QgsHistogram();
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/** Assigns numeric source values for the histogram.
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* @param values list of doubles
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*/
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void setValues( const QList<double>& values );
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/** Assigns numeric source values for the histogram from a vector layer's field or as the
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* result of an expression.
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* @param layer vector layer
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* @param fieldOrExpression field name or expression to be evaluated
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* @returns true if values were successfully set
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*/
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bool setValues( QgsVectorLayer* layer, const QString& fieldOrExpression );
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/** Calculates the optimal bin width using the Freedman-Diaconis rule. Bins widths are
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* determined by the inter-quartile range of values and the number of values.
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* @returns optimal width for bins
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* @see optimalNumberBins
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* @note values must first be specified using @link setValues @endlink
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*/
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double optimalBinWidth() const;
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/** Returns the optimal number of bins for the source values, calculated using the
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* Freedman-Diaconis rule. The number of bins are determined by the inter-quartile range
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* of values and the number of values.
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* @returns optimal number of bins
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* @see optimalBinWidth
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* @note values must first be specified using @link setValues @endlink
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*/
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int optimalNumberBins() const;
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/** Returns a list of edges for the histogram for a specified number of bins. This list
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* will be length bins + 1, as both the first and last value are also included.
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* @param bins number of bins
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* @return list of bin edges
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* @note values must first be specified using @link setValues @endlink
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*/
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QList<double> binEdges( int bins ) const;
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/** Returns the calculated list of the counts for the histogram bins.
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* @param bins number of histogram bins
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* @return list of histogram counts
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* @note values must first be specified using @link setValues @endlink
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*/
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QList<int> counts( int bins ) const;
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};
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