QwtPyPlot Class Reference

Matplotlib pyplot-like interface for Qwt plotting. More...

#include <qwt_pyplot.h>

Inheritance diagram for QwtPyPlot:

Classes
class	PrivateData

Public Member Functions
	QwtPyPlot (QwtFigure *figure, QObject *parent=nullptr)
	QwtPyPlot (QwtPlot *plot, QObject *parent=nullptr)
QwtFigure *	gcf () const
QwtPlot *	gca () const
void	sca (QwtPlot *plot)
QwtPlot *	subplot (int rows, int cols, int index)
	Create a subplot in a grid layout.
QwtPlot *	addAxes (const QRectF &rect=QRectF(0.1, 0.1, 0.8, 0.8))
QwtPlot *	twinx (QwtPlot *host=nullptr)
QwtPlot *	twiny (QwtPlot *host=nullptr)
void	tightLayout ()
QwtPlotCurve *	plot (const QVector< double > &y, const QString &fmt=QString(), const QString &label=QString())
QwtPlotCurve *	plot (const QVector< double > &x, const QVector< double > &y, const QString &fmt=QString(), const QString &label=QString())
QwtPlotCurve *	plot (const QVector< QPointF > &data, const QString &fmt=QString(), const QString &label=QString())
QwtPlotCurve *	scatter (const QVector< double > &x, const QVector< double > &y, double size=20, const QString &color=QString(), const QString &label=QString())
	Create a scatter plot (markers only, no lines)
QwtPlotBarChart *	bar (const QVector< double > &values, const QString &color=QString(), const QString &label=QString())
QwtPlotBarChart *	bar (const QVector< double > &x, const QVector< double > &values, double width=0.8, const QString &color=QString(), const QString &label=QString())
QwtPlotHistogram *	hist (const QVector< double > &data, int bins=10, const QString &color=QString(), const QString &label=QString())
	Create a histogram from raw data with automatic binning.
QwtPlotBoxChart *	boxplot (const QVector< QwtBoxSample > &data, const QString &label=QString())
QwtPlotIntervalCurve *	fillBetween (const QVector< double > &x, const QVector< double > &y1, const QVector< double > &y2, const QString &color=QString(), double alpha=0.3)
	Fill the area between two curves.
QwtPlotIntervalCurve *	errorbar (const QVector< double > &x, const QVector< double > &y, const QVector< double > &yerr, const QString &fmt=QString(), const QString &label=QString())
	Create error bars with symmetric y-error.
QwtPlotSpectrogram *	imshow (const QVector< QVector< double > > &data, const QString &cmap="viridis", double vmin=0.0, double vmax=0.0)
	Display a 2D matrix as a color-mapped image.
QwtPlotSpectrogram *	contour (const QVector< QVector< double > > &data, const QList< double > &levels={}, const QString &cmap="viridis")
	Draw contour lines from a 2D matrix.
QwtPlotVectorField *	quiver (const QVector< double > &x, const QVector< double > &y, const QVector< double > &u, const QVector< double > &v, const QString &color=QString())
	Create a quiver (vector field) plot.
QwtPlotTradingCurve *	candlestick (const QVector< QwtOHLCSample > &data, const QString &label=QString())
QwtPlotGrid *	grid (bool show=true, bool minor=false)
QwtPlotMarker *	axhline (double y, const QString &fmt=QString())
QwtPlotMarker *	axvline (double x, const QString &fmt=QString())
QwtPlotZoneItem *	axhspan (double y1, double y2, const QString &color=QString(), double alpha=0.3)
QwtPlotZoneItem *	axvspan (double x1, double x2, const QString &color=QString(), double alpha=0.3)
QwtPlotArrowMarker *	annotate (const QString &text, const QPointF &xy, const QPointF &xytext)
QwtPlotLegendItem *	legend (const QString &loc="best")
void	setTitle (const QString &title)
void	setXLabel (const QString &label)
void	setYLabel (const QString &label)
void	setXLim (double min, double max)
void	setYLim (double min, double max)
void	setXScale (const QString &scale)
void	setYScale (const QString &scale)
void	setXTicks (const QVector< double > &ticks, const QStringList &labels={})
void	setYTicks (const QVector< double > &ticks, const QStringList &labels={})
void	invertXAxis ()
void	invertYAxis ()
void	setFaceColor (const QString &color)
void	setAxesColor (const QString &color)
void	colorbar (QwtPlotSpectrogram *spectro=nullptr)
bool	savefig (const QString &filename, int dpi=-1)
void	show ()
void	enablePan (bool enable=true)
void	enableZoom (bool enable=true)

Detailed Description

Matplotlib pyplot-like interface for Qwt plotting.

QwtPyPlot provides a high-level, stateful API inspired by matplotlib's pyplot module. It wraps a QwtFigure (or a single QwtPlot) and delegates all operations to the existing Qwt infrastructure (QwtPlotFactory, QwtPlotStyling, etc.).

The class maintains a "current axes" pointer (like matplotlib's gca()), so successive calls to plot(), setTitle(), etc. always operate on the active subplot.

Example:

// Create a figure with 2 subplots
QwtFigure* fig = new QwtFigure;
QwtPyPlot plt(fig);
 
plt.subplot(2, 1, 1);
plt.plot({0, 1, 2, 3}, {1, 4, 2, 5}, "r-o", "Temperature");
plt.setTitle("Sensor Data");
plt.grid(true);
plt.legend();
 
plt.subplot(2, 1, 2);
plt.bar({10, 20, 30, 40}, "b", "Sales");
 
plt.savefig("output.png", 300);
fig->show();

Single-plot mode:

QwtPlot* plot = new QwtPlot;
QwtPyPlot plt(plot);
plt.plot(x, y, "b--");
plt.scatter(x2, y2, 50, "r");
plot->show();

See also

QwtFigure, QwtPlot, QwtPlotFactory, QwtPlotStyling

Member Function Documentation

contour()

QwtPlotSpectrogram * QwtPyPlot::contour	(	const QVector< QVector< double > > &	data,
		const QList< double > &	levels = {},
		const QString &	cmap = "viridis"
	)

Draw contour lines from a 2D matrix.

Parameters

data	2D matrix (rows x cols)
levels	Contour levels (empty = auto-generate 10 levels)
cmap	Color map name

Returns

The created spectrogram with contour mode

errorbar()

QwtPlotIntervalCurve * QwtPyPlot::errorbar	(	const QVector< double > &	x,
		const QVector< double > &	y,
		const QVector< double > &	yerr,
		const QString &	fmt = QString(),
		const QString &	label = QString()
	)

Create error bars with symmetric y-error.

Parameters

x	X coordinates
y	Y values (center)
yerr	Error values (symmetric)
fmt	Format string for the center line
label	Legend label

Returns

The created interval curve representing error bars

fillBetween()

QwtPlotIntervalCurve * QwtPyPlot::fillBetween	(	const QVector< double > &	x,
		const QVector< double > &	y1,
		const QVector< double > &	y2,
		const QString &	color = QString(),
		double	alpha = 0.3
	)

Fill the area between two curves.

Parameters

x	X coordinates
y1	Upper curve values
y2	Lower curve values
color	Fill color
alpha	Fill opacity (0.0-1.0)

Returns

The created interval curve

hist()

QwtPlotHistogram * QwtPyPlot::hist	(	const QVector< double > &	data,
		int	bins = 10,
		const QString &	color = QString(),
		const QString &	label = QString()
	)

Create a histogram from raw data with automatic binning.

Parameters

data	Raw data values
bins	Number of bins
color	Bar color
label	Legend label

Returns

The created histogram

imshow()

QwtPlotSpectrogram * QwtPyPlot::imshow	(	const QVector< QVector< double > > &	data,
		const QString &	cmap = "viridis",
		double	vmin = 0.0,
		double	vmax = 0.0
	)

Display a 2D matrix as a color-mapped image.

Parameters

data	2D matrix (rows x cols)
cmap	Color map name ("viridis", "hot", "cool", "jet", "gray")
vmin	Minimum value for color scaling (0 = auto)
vmax	Maximum value for color scaling (0 = auto)

Returns

The created spectrogram

quiver()

QwtPlotVectorField * QwtPyPlot::quiver	(	const QVector< double > &	x,
		const QVector< double > &	y,
		const QVector< double > &	u,
		const QVector< double > &	v,
		const QString &	color = QString()
	)

Create a quiver (vector field) plot.

Parameters

x	X positions
y	Y positions
u	X components of vectors
v	Y components of vectors
color	Arrow color

Returns

The created vector field

scatter()

QwtPlotCurve * QwtPyPlot::scatter	(	const QVector< double > &	x,
		const QVector< double > &	y,
		double	size = 20,
		const QString &	color = QString(),
		const QString &	label = QString()
	)

Create a scatter plot (markers only, no lines)

Parameters

x	X coordinates
y	Y coordinates
size	Marker size in points
color	Color name (e.g. "r", "blue", "#ff0000")
label	Legend label

Returns

The created curve

subplot()

QwtPlot * QwtPyPlot::subplot	(	int	rows,
		int	cols,
		int	index
	)

Create a subplot in a grid layout.

Parameters

rows	Number of rows in the grid
cols	Number of columns in the grid
index	1-based index of the subplot (row-major order)

Returns

The newly created QwtPlot

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The documentation for this class was generated from the following files:

• /home/runner/work/QWT/QWT/src/plot/qwt_pyplot.h
• /home/runner/work/QWT/QWT/src/plot/qwt_pyplot.cpp