PyQtGraph Canvas

PyQtGraph is a data visualization library based on Qt. It provides variety of plot canvases and plot items that can be operated in a interactive way. The magicclass.ext.pyqtgraph submodule tries to integrate many of the pyqtgraph widgets to provide a consistent, magicgui-like API.

You have to install pyqtgraph in advance.

pip install pyqtgraph

Then several pyqtgraph canvases are now available.

from magicclass.ext.pyqtgraph import QtPlotCanvas  # 1-D plot, like plt.plot
from magicclass.ext.pyqtgraph import QtMultiPlotCanvas  # multiple QtPlotCanvas
from magicclass.ext.pyqtgraph import QtImageCanvas  # 2-D image, like plt.imshow
from magicclass.ext.pyqtgraph import QtMultiImageCanvas  # multiple QtImageCanvas

QtPlotCanvas

QtPlotCanvas is a canvas for 1-D plotting.

from magicclass.ext.pyqtgraph import QtPlotCanvas

canvas = QtPlotCanvas()
canvas.show()

A QtPlotCanvas is composed of several \"layers\" and each layer corresponds to a plot item that is in the canvas. Basically you\'ll add new layers to visualize data.

Methods and Attributes

• Major methods
  • add_curve() ... Add a curve possibly with symbols, similar to plt.plot.
  • add_scatter() ... Add scatter plot item, similar to plt.scatter.
  • add_hist() ... Build a histogram from input data, similar to plt.hist.
  • add_bar() ... Add a bar plot, similar to plt.bar.
  • add_infline() ... Add a infinite line, similar to plt.axline.
  • add_text() ... Add list of texts, similar to plt.text.
  • show() ... Show canvas.
• Major attributes and properties
  • layers ... List of all the layers.
  • visible ... Visibility of canvas.
  • enabled ... Interactivity of canvas.
  • xlim ... Minumum and maximum value of x-axis in viewbox.
  • ylim ... Minumum and maximum value of y-axis in viewbox.
  • xlabel ... Label text of x-axis.
  • ylabel ... Label text of y-axis.
  • title ... Title text of the plot canvas.
  • legend ... Legend item of the canvas.
  • mouse_click_callbacks ... list of callback functions that will get called on mouse click.

Add curves

add_curve method will add a Curve layer to the canvas, store the layer in the layers attribute and return the layer.

xdata = np.linspace(0, np.pi, 200)
ydata = np.sin(xdata) * np.exp(-xdata)
layer = canvas.add_curve(xdata, ydata)  # or canvas.add_curve(ydata) if you don't need x scale.

There are other keyword argument that will be useful to visualize differently.

canvas.add_curve(xdata, ydata, name="Data-1")  # name of the layer
canvas.add_curve(xdata, ydata, edge_color="yellow")  # change color
canvas.add_curve(xdata, ydata, lw=4, ls="--")  # change line width and line style
canvas.add_curve(xdata, ydata, symbol="+")  # show symbol at the data points

Layer is available in layers.

layer = canvas.layers[0]  # the first layer

Handle layers

The layer objects are also designed to be easily

1. Show/hide layer

   layer.visible = True  # show
   layer.visible = False  # hide
   

2. Change color

   layer.face_color = "red"  # str
   layer.face_color = [0.4, 0.2, 0.2, 1.0]  # float RGBA
   layer.edge_color = [0.4, 0.2, 0.2, 1.0]  # change edge color
   layer.color = "white"  # change face color and edge color
   

3. Get data

   layer.xdata  # the x data
   layer.ydata  # the y data
   

QtMultiPlotCanvas

QtMultiPlotCanvas is a collection of QtPlotCanvas.

from magicclass.ext.pyqtgraph import QtMultiPlotCanvas

canvas = QtMultiPlotCanvas(1, 2)  # 1 x 2 canvases
canvas.show()

If you want to synchronize axes movements, set sharex and sharey.

canvas = QtMultiPlotCanvas(2, 2, sharex=True, sharey=True)

The i-th canvas is available by simple indexing. Returned items have the same API as QtPlotCanvas.

canvas[0].add_curve(np.random.random(100))  # add curve to the 0-th canvas.
canvas[1].layers  # Layer list of the 1st canvas.