PyQwt Reference Guide

PyQt4.Qwt5

The reference should be used in conjunction with the Qwt manual. Only the differences specific to the Python bindings are documented here.

In this chapter, is not yet implemented implies that the feature can be easily implemented if needed, is not implemented implies that the feature is not easily implemented, and is not Pythonic implies that the feature will not be implemented because it violates the Python philosophy (e.g. may use dangling pointers).

If a class is described as being is fully implemented then all non-private member functions and all public class variables have been implemented.

Undocumented classes have not yet been implemented or are still experimental.

Class reference

class QwtAbstractScale

is fully implemented.

class QwtAbstractScaleDraw

is fully implemented.

class QwtAbstractSlider

is fully implemented.

class QwtAlphaColorMap

is fully implemented.

class QwtArrayData

is fully implemented.

class QwtArrayDouble

is fully implemented. See Template reference.

class QwtArrayInt

is fully implemented. See Template reference.

class QwtArrayQwtDoubleInterval

is fully implemented. See Template reference.

class QwtArrayQwtDoublePoint

is fully implemented. See Template reference.

class QwtArrowButton

is fully implemented.

class QwtClipper

is fully implemented, but only available when PyQwt wraps Qwt-5.1.x.

class QwtColorMap

is fully implemented.

class QwtCompass

is fully implemented.

class QwtCompassMagnetNeedle

is fully implemented.

class QwtCompassRose

is fully implemented.

class QwtCompassWindArrow

is fully implemented.

class QwtCounter

is fully implemented.

class QwtCurveFitter

is fully implemented.

class QwtData

is fully implemented.

class QwtDial

is fully implemented.

class QwtDialNeedle

is fully implemented.

class QwtDialScaleDraw

is fully implemented.

class QwtDialSimpleNeedle

is fully implemented.

class QwtDoubleInterval

is fully implemented.

class QwtDoublePoint

is fully implemented, but only available when PyQt wraps Qt-3. When PyQt wraps Qt-4, replace this class with QPointF except in signals. For example, clicking in the canvas of the plot displayed by the following program:

#!/usr/bin/env python

import sys
from PyQt4 import Qt
import PyQt4.Qwt5 as Qwt

def aSlot(aQPointF):
    print 'aSlot gets:', aQPointF

# aSlot()

def make():
    demo = Qwt.QwtPlot()
    picker = Qwt.QwtPlotPicker(Qwt.QwtPlot.xBottom,
                               Qwt.QwtPlot.yLeft,
                               Qwt.QwtPicker.PointSelection,
                               Qwt.QwtPlotPicker.CrossRubberBand,
                               Qwt.QwtPicker.AlwaysOn,
                               demo.canvas())
    picker.connect(
        picker, Qt.SIGNAL('selected(const QwtDoublePoint&)'), aSlot)
    return demo

# make()

def main(args):
    app = Qt.QApplication(args)
    demo = make()
    demo.show()
    sys.exit(app.exec_())

# main()

if __name__ == '__main__':
    main(sys.argv)

# Local Variables: ***
# mode: python ***
# End: ***

shows that the signal returns an object of type QPointF:

aSlot gets: <PyQt4.QtCore.QPointF object at 0x2aaaaf73be20>

class QwtDoubleRange

is fully implemented.

class QwtDoubleRect

is fully implemented, but only available when PyQt wraps Qt-3.

When PyQt wraps Qt-4, replace this class with QRectF except in signals: see QwtDoublePoint.

class QwtDoubleSize

is fully implemented, but only available when PyQt wraps Qt-3.

When PyQt wraps Qt-4, replace this class with QSizeF except in signals: see QwtDoublePoint.

class QwtDynGridLayout

is fully implemented.

class QwtEventPattern

is fully implemented.

class QwtIntervalData

is fully implemented.

class QwtKnob

is fully implemented.

class QwtLegend

is fully implemented.

class QwtLegendItem

is fully implemented.

class QwtLegendItemManager

is fully implemented, but only available when PyQwt wraps Qwt-5.1.x.

class QwtLinearColorMap

is fully implemented.

class QwtLinearScaleEngine

is fully implemented.

class QwtLog10ScaleEngine

is fully implemented.

class QwtLegendMagnifier

is fully implemented, but only available when PyQwt wraps Qwt-5.1.x.

class QwtMetricsMap

is fully implemented.

class QwtPaintBuffer

is fully implemented when PyQt wraps Qt-3.

class QwtPainter

is fully implemented.

class QwtPanner

is fully implemented.

class QwtPicker

is fully implemented.

class QwtPickerClickPointMachine

is fully implemented.

class QwtPickerClickRectMachine

is fully implemented.

class QwtPickerDragPointMachine

is fully implemented.

class QwtPickerDragRectMachine

is fully implemented.

class QwtPickerMachine

is fully implemented.

class QwtPickerPolygonMachine

is fully implemented.

class QwtPlainTextEngine

is fully implemented.

class QwtPlot

is fully implemented, but:

void QwtPlot::print(QPrinter& printer, const QwtPlotPrintFilter& filter)

is implemented as:

plot.print_(printer, filter)

void QwtPlot::print(QPainter* painter, const QRect& rect, const QwtPlotPrintFilter& filter)

is implemented as:

plot.print_(painter, rect, filter)

class QwtPlotCanvas

is fully implemented.

class QwtPlotCurve

is fully implemented, but:

void QwtPlotCurve::setData(double* x, double* y, int size)

is implemented as:

curve.setData(x, y)

where x and y can be any combination of lists, tuples and Numerical Python arrays. The data is copied to C++ data types.

void QwtPlotCurve::setRawData(double* x, double* y, int size)

is not Pythonic.

class QwtPlotDict

is fully implemented. FIXME: is the auto delete feature dangerous?

class QwtPlotGrid

is fully implemented.

class QwtPlotItem

is fully implemented.

class QwtPlotLayout

is fully implemented.

class QwtPlotMagnifier

is fully implemented.

class QwtPlotMarker

is fully implemented.

class QwtPlotPanner

is fully implemented.

class QwtPlotPicker

is fully implemented, but:

QwtText QwtPlotPicker::trackerText(QwtDoublePoint& point)

is implemented as:

qwtText = plotPicker.trackerText(point)

where point is a QwtDoublePoint when PyQt wraps Qt-3 or a QPointF when PyQt wraps Qt-4.

class QwtPlotPrintFilter

is fully implemented.

class QwtPlotRasterItem

is fully implemented.

class QwtPlotScaleItem

is fully implemented, but only available when PyQwt wraps Qwt-5.1.x.

class QwtPlotSpectrogram

The protected member functions

QMap<double, QPolygonF> QwtPlotSpectogram::renderContourLines(const QwtDoubleRect&, const QSize&) const

and

void QwtPlotSpectogram::drawContourLines(QPainter*, const QwtScaleMap&, const QwtScaleMap&, const QMap<double, QPolygonF>&) const

are not yet implemented.

class QwtPlotSvgItem

is fully implemented.

class QwtPlotZoomer

is fully implemented.

class QwtPolygon

When PyQt wraps Qt-3, replace this class with QPointArray except in signals: see QwtDoublePoint.

When PyQt has been built for Qt-4, replace this class with QPolygon except in signals: see QwtDoublePoint.

class QwtPolygonFData

is fully implemented.

class QwtRasterData

is fully implemented.

class QwtRect

is fully implemented.

class QwtRichTextEngine

is fully implemented.

class QwtRoundScaleDraw

is fully implemented.

class QwtScaleArithmic

is fully implemented.

class QwtScaleDiv

QwtScaleDiv::QwtScaleDiv(const QwtDoubleInterval&, QwtValueList*)

is implemented as:

scaleDiv = QwtScaleDiv(
    qwtDoubleInterval, majorTicks, mediumTicks, minorTicks)

QwtScaleDiv::QwtScaleDiv(double, double, QwtTickList*)

is implemented as:

scaleDiv = QwtScaleDiv(
    lower, upper, majorTicks, mediumTicks, minorTicks)

class QwtScaleDraw

is fully implemented.

class QwtScaleEngine

is fully implemented.

class QwtScaleMap

is fully implemented.

QwtScaleMap::QwtScaleMap(int, int, double, double)

does not exist in C++, but is provided by PyQwt.

class QwtScaleTransformation

is fully implemented.

class QwtScaleWidget

is fully implemented.

class QwtSimpleCompassRose

is fully implemented.

class QwtSlider

is fully implemented.

class QwtSpline

is fully implemented.

class QwtSplineCurveFitter

is fully implemented.

class QwtSymbol

is fully implemented.

class QwtText

is fully implemented.

class QwtTextEngine

is fully implemented.

class QwtTextLabel

is fully implemented.

class QwtThermo

is fully implemented.

class QwtWheel

is fully implemented.

Function reference

toImage(array)

Convert array to a QImage, where array must be a 2D NumPy, numarray, or Numeric array containing data of type uint8 or uin32.

toNumarray(image)

Convert image to a 2D numarray array, where image must be a QImage with depth 8 or 32. The resulting 2D numarray array contains data of type uint8 or uint32.

toNumeric(image)

Convert image to a 2D Numeric array, where image must be a QImage of depth 8 or 32. The resulting 2D Numeric array contains data of type uint8 or uint32.

toNumpy(image)

Convert image to a 2D NumPy array, where image must be a QImage of depth 8 or 32. The resulting 2D NumPy array contains data of type uint8 or uint32.

to_na_array(image)

Deprecated. Use toNumarray().

to_np_array(image)

Deprecated. Use toNumeric().

Template reference

PyQwt has a partial interface to the following QwtArray<T> templates:

1. QwtArrayDouble for QwtArray<double>
2. QwtArrayInt for QwtArray<int>
3. QwtArrayQwtDoubleInterval for QwtArray<QwtDoubleInterval>
4. QwtArrayQwtDoublePoint for QwtArray<QwtDoublePoint> when PyQt has been built against Qt-3 or for QwtArray<QPointF> when PyQt has been built against Qt-4.

Those classes have at least 3 constructors, taking QwtArrayDouble as an example:

1. array = QwtArrayDouble()
2. array = QwtArrayDouble(int)
3. array = QwtArrayDouble(otherArray)

QwtArrayDouble and QwtArrayInt have also a constructor which takes a sequence of items convertable to a C++ double and a C++ long. For instance:

• array = QwtArrayDouble(numpy.array([0.0, 1.0]))
• array = QwtArrayInt(numpy.array([0, 1]))

All those classes have 16 member functions, taking QwtArrayDouble as example:

1. array = array.assign(otherArray)
2. item = array.at(index)
3. index = array.bsearch(item)
4. index = contains(item)
5. array = otherArray.copy()
6. result = array.count()
7. array.detach()
8. array = array.duplicate(otherArray)
9. bool = array.fill(item, index=-1)
10. index = array.find(item, index=0)
11. bool = array.isEmpty()
12. bool = array.isNull()
13. bool = array.resize(index)
14. result = array.size()
15. array.sort()
16. bool = array.truncate(index)

Iterators are not yet implemented. However, the implementation of the special class methods __getitem__, __len__ and __setitem__ let you use those classes almost as a sequence. For instance:

>>> from PyQt4.Qwt5 import *
>>> import numpy as np
>>> a = QwtArrayDouble(np.arange(10, 20, 4))
>>> for i in a:                                  # thanks to __getitem__
...  print i
...
10.0
14.0
18.0
>>> for i in range(len(a)):                      # thanks to __len__
...  print a[i]                                  # thanks to __getitem__
...
10.0
14.0
18.0
>>> for i in range(len(a)):                      # thanks to __len__
...  a[i] = 10+3*i                               # thanks to __setitem__
...
>>> for i in a:                                  # thanks to __getitem__
...  print i
...
10.0
13.0
16.0

PyQt4.Qwt5.qplt

Provides a command line interpreter friendly layer over QwtPlot. An example of its use is:

>>> import numpy as np
>>> from PyQt4.Qt import *
>>> from PyQt4.Qwt5 import *
>>> from PyQt4.Qwt5.qplt import *
>>> application = QApplication([])
>>> x = np.arange(-2*np.pi, 2*np.pi, 0.01)
>>> p = Plot(
...  Curve(x, np.cos(x), Pen(Magenta, 2), 'cos(x)'),
...  Curve(x, np.exp(x), Pen(Red), 'exp(x)', Y2),
...  Axis(Y2, Log),
...  'PyQwt using Qwt-%s -- http://qwt.sf.net' % QWT_VERSION_STR)
>>> QPixmap.grabWidget(p).save('cli-plot-1.png', 'PNG')
True
>>> x = x[0:-1:10]
>>> p.plot(
...  Curve(x, np.cos(x-np.pi/4), Symbol(Circle, Yellow), 'circle'),
...  Curve(x, np.cos(x+np.pi/4), Pen(Blue), Symbol(Square, Cyan), 'square'))
>>> QPixmap.grabWidget(p).save('cli-plot-2.png', 'PNG')
True

class Axis(*rest)

A command line interpreter friendly class.

The interpretation of the *rest parameters is type dependent:

• QwtPlot.Axis: sets the orientation of the axis.
• QwtScaleEngine: sets the axis type (Lin or Log).
• int : sets the attributes of the axis.
• string or QString: sets the title of the axis.

class Curve(x, y, *rest)

A command line friendly layer over QwtPlotCurve.

Parameters:

• x: sequence of numbers
• y: sequence of numbers

The interpretation of the *rest parameters is type dependent:

• Axis: attaches an axis to the curve.
• Pen: sets the pen to connect the data points.
• Symbol: sets the symbol to draw the data points.
• str, QString, or QwtText: sets the curve title.

class IPlot(*rest)

A QMainWindow widget with a Plot widget as central widget. It provides:

1. a toolbar for printing and piping into Grace.
2. a legend with control to toggle curves between hidden and shown.
3. mouse tracking to display the coordinates in the status bar.
4. an infinite stack of zoom regions.

The interpretation of the rest parameters is type dependent:

• Axis: enables the axis.
• Curve: adds a curve.
• str or QString: sets the title.
• int: sets a set of mouse events to the zoomer actions.
• (int, int): sets the size.

class Pen(*rest)

A command line friendly layer over QPen.

The interpretation of the *rest parameters is type dependent:

• Qt.PenStyle: sets the pen style.
• QColor or Qt.GlobalColor: sets the pen color.
• int: sets the pen width.

class Plot(*rest)

A command line interpreter friendly layer over QwtPlot.

The interpretation of the *rest parameters is type dependent:

• Axis: enables the axis.
• Curve: adds a curve.
• str or QString: sets the title.
• int: sets a set of mouse events to the zoomer actions.
• (int, int): sets the size.
• QWidget: sets the parent widget

clearZoomStack()

Force autoscaling and clear the zoom stack

formatCoordinates(x, y)

Format mouse coordinates as real world plot coordinates.

gracePlot(saveall='', pause=0.2)

Clone the plot into Grace for very high quality hard copy output.

Know bug: Grace does not scale the data correctly when Grace cannot cannot keep up with gracePlot. This happens when it takes too long to load Grace in memory (exit the Grace process and try again) or when ‘pause’ is too short.

plot(*rest)

Plot additional curves and/or axes.

The interpretation of the *rest parameters is type dependent:

• Axis: enables the axis.
• Curve: adds a curve.

setZoomerMouseEventSet(index)

Attach the Qwt.QwtPlotZoomer actions to a set of mouse events.

toggleVisibility(plotItem)

Toggle the visibility of a plot item

class Symbol(*rest)

A command line friendly layer over QwtSymbol.

The interpretation of the *rest parameters is type dependent:

• QColor or Qt.GlobalColor: sets the symbol fill color.
• QwtSymbol.Style: sets symbol style.
• int: sets the symbol size.

PyQt4.Qwt5.grace

class GraceProcess(debug=None)

Provides a simple interface to a Grace subprocess.