This may be more than you asked for…
I have a Toolbar subclass that adds a button to graphically select a subset from the data, its sort of similar to the zoom tool only it doesnt zoom. This is specific to Qt4, but maybe you will find it useful. Toolbar._init_toolbar adds a “Select” action, which is wired so that one corner of a rectangle is defined by the mouse press, the opposite by the mouse release:
class Toolbar(MplToolbar):
def init(self, *args, **kwargs):
pixmap = QtGui.QPixmap()
pixmap.load(‘:/cross.png’)
mplCursors.SELECT_POINT = pixmap
super(Toolbar, self).init(*args, **kwargs)
def _init_toolbar(self):
self.basedir = os.path.join(mpl.rcParams[ ‘datapath’ ],‘images’)
a = self.addAction(self._icon(‘home.svg’), ‘Home’, self.home)
a.setToolTip(‘Reset original view’)
a = self.addAction(self._icon(‘back.svg’), ‘Back’, self.back)
a.setToolTip(‘Back to previous view’)
a = self.addAction(self._icon(‘forward.svg’), ‘Forward’, self.forward)
a.setToolTip(‘Forward to next view’)
self.addSeparator()
a = self.addAction(self._icon(‘move.svg’), ‘Pan’, self.pan)
a.setToolTip(‘Pan axes with left mouse, zoom with right’)
a = self.addAction(self._icon(‘zoom_to_rect.svg’), ‘Zoom’, self.zoom)
a.setToolTip(‘Zoom to rectangle’)
a = self.addAction(QtGui.QIcon(‘:/crosshairs.svg’), ‘Select’,
self.selectPointMode)
a.setToolTip(‘Select the nearest data point’)
self.addSeparator()
a = self.addAction(self._icon(‘subplots.png’), ‘Subplots’,
self.configure_subplots)
a.setToolTip(‘Configure subplots’)
a = self.addAction(self._icon(‘filesave.svg’), ‘Save’,
self.save_figure)
a.setToolTip(‘Save the figure’)
self.buttons = {}
Add the x,y location widget at the right side of the toolbar
The stretch factor is 1 which means any resizing of the toolbar
will resize this label instead of the buttons.
if self.coordinates:
self.locLabel = QtGui.QLabel( “”, self )
self.locLabel.setAlignment(
QtCore.Qt.AlignRight | QtCore.Qt.AlignTop )
self.locLabel.setSizePolicy(
QtGui.QSizePolicy(QtGui.QSizePolicy.Expanding,
QtGui.QSizePolicy.Ignored))
labelAction = self.addWidget(self.locLabel)
labelAction.setVisible(True)
reference holder for subplots_adjust window
self.adj_window = None
def mouse_move(self, event):
#print ‘mouse_move’, event.button
if not event.inaxes or not self._active:
if self._lastCursor != mplCursors.POINTER:
self.set_cursor(mplCursors.POINTER)
self._lastCursor = mplCursors.POINTER
else:
if self._active==‘ZOOM’:
if self._lastCursor != mplCursors.SELECT_REGION:
self.set_cursor(mplCursors.SELECT_REGION)
self._lastCursor = mplCursors.SELECT_REGION
if self._xypress:
x, y = event.x, event.y
lastx, lasty, a, ind, lim, trans = self._xypress[0]
self.draw_rubberband(event, x, y, lastx, lasty)
elif (self._active==‘PAN’ and
self._lastCursor != mplCursors.MOVE):
self.set_cursor(mplCursors.MOVE)
self._lastCursor = mplCursors.MOVE
elif self._active==‘SELECT’:
if self._lastCursor != mplCursors.SELECT_POINT:
QtGui.QApplication.restoreOverrideCursor()
QtGui.QApplication.setOverrideCursor(
QtGui.QCursor(mplCursors.SELECT_POINT))
self._lastCursor = mplCursors.SELECT_POINT
if event.inaxes and event.inaxes.get_navigate():
try: s = event.inaxes.format_coord(event.xdata, event.ydata)
except ValueError: pass
except OverflowError: pass
else:
if len(self.mode):
self.set_message(‘%s : %s’ % (self.mode, s))
else:
self.set_message(s)
else: self.set_message(self.mode)
def selectPointMode(self, *args):
if self._active == ‘SELECT’:
self._active = None
else:
self._active = ‘SELECT’
if self._idPress is not None:
self._idPress = self.canvas.mpl_disconnect(self._idPress)
self.mode = ‘’
if self._idRelease is not None:
self._idRelease = self.canvas.mpl_disconnect(self._idRelease)
self.mode = ‘’
if self._active:
self._idRelease = self.canvas.mpl_connect(
‘button_press_event’, self.selectPoint)
self.mode = ‘pixel select mode’
self.canvas.widgetlock(self)
else:
self.canvas.widgetlock.release(self)
self.set_message(self.mode)
def selectPoint(self, event):
if event.inaxes and event.inaxes.get_navigate():
self.xdatastart=event.xdata
self.ydatastart=event.ydata
self.xstart=event.x
self.ystart=event.y
self._banddraw = self.canvas.mpl_connect(
‘motion_notify_event’,self.drawband)
self._idRelease = self.canvas.mpl_disconnect(self._idRelease)
self._idRelease = self.canvas.mpl_connect(
‘button_release_event’, self.selectSecondPoint)
def selectSecondPoint(self, event):
if event.inaxes and event.inaxes.get_navigate():
self._banddraw=self.canvas.mpl_disconnect(self._banddraw)
self._idRelease = self.canvas.mpl_disconnect(self._idRelease)
self._idRelease = self.canvas.mpl_connect(
‘button_press_event’, self.selectPoint)
self.draw_rubberband(event, 0, 0, 0, 0)
self.emit(
QtCore.SIGNAL(‘pickEvent’),
self.xdatastart,
self.ydatastart,
event.xdata,
event.ydata
)
def drawband(self, event):
self.draw_rubberband(event,self.xstart, self.ystart, event.x, event.y)
The mouse release calls selectSecondPoint, which emits a signal containing the x and y start and end data. That gets routed to the onPick method on my Qt4Canvas instance:
def onPick(self, xstart, ystart, xend, yend):
xstart_i, ystart_i = self.getIndices(xstart, ystart)
xend_i, yend_i = self.getIndices(xend, yend)
if xstart_i > xend_i: xstart_i, xend_i = xend_i, xstart_i
if ystart_i > yend_i: ystart_i, yend_i = yend_i, ystart_i
try:
indices = self.indices[ystart_i:yend_i+1, xstart_i:xend_i+1]
self.emit(QtCore.SIGNAL(‘pickEvent’), indices.flatten())
except TypeError:
pass
which determines the indices of my data that are contained within the region defined by the user:
def getIndices(self, xdata, ydata):
xIndex = locateClosest(xdata, self.xPixelLocs)
yIndex = locateClosest(ydata, self.yPixelLocs)
return xIndex, yIndex
def locateClosest(point, points):
compare = numpy.abs(points-point)
return numpy.nonzero(numpy.ravel(compare==compare.min()))[0]
···
On Tuesday 11 November 2008 09:03:30 am jansohn@…2379… wrote:
Dear all,
after looking around for a plotting library I found Matplotlib and I tried
to create a gray scale image in a wxpython application. Looks good!
Now I have to find a line in the image with mainly vertical orientation. To
do this a crosshair cursor would be fine. In Pylab I found a SpanSelector
which also looks promising.
Unfortunately I failed in adding a crosshair cursor or a SpanSelector into
my wxpython application figure.
Does anyone have an example add hand showing me how to achieve this?