# PythonQt properties shadowing methods
**URL:** https://discourse.slicer.org/t/pythonqt-properties-shadowing-methods/16992
**Category:** Development
**Created:** [April 8, 2021, 1:38am UTC](https://discourse.slicer.org/t/pythonqt-properties-shadowing-methods/16992 "2021-04-08T01:38:10Z")
**Posts on this page:** 1
**Showing post:** 9
### Author:  [@fbordignon](https://discourse.slicer.org/u/fbordignon)
#### Post date: [August 30, 2021, 1:14pm UTC](https://discourse.slicer.org/t/pythonqt-properties-shadowing-methods/16992/9 "2021-08-30T13:14:19Z")
For this example, the user needs to have the [python3.dll fix](https://github.com/Slicer/Slicer/pull/5822), alternatively one can temporarily [download and install WinPython 3.6.7](https://sourceforge.net/projects/winpython/files/WinPython_3.6/3.6.7.0/WinPython64-3.6.7.0Zero.exe/download) and copy python3.dll from `winpython/python-3.6.7.amd64/python3.dll` to `Slicer/bin/python3.dll`
Slicer can crash if one does not have PythonQt compiled with [this fix](https://github.com/commontk/PythonQt/pull/81). It works without it, but Slicer can become unstable.
Working example based on [plotting example of pyqtgraph](https://github.com/pyqtgraph/pyqtgraph/blob/master/examples/Plotting.py):
```python
# Copy and paste this on Slicer's python terminal
pip_install('pyside2==5.15.1') # must be important to match pyside2 version to slicer's qt version
pip_install('pyqtgraph')
import textwrap
from PySide2.QtWidgets import QVBoxLayout
import shiboken2
import numpy as np
from pyqtgraph.Qt import QtGui, QtCore
import pyqtgraph as pg
# Custom layout base class
class BaseLayout:
TAG = "EmptyScreen"
UID = 1010
LAYOUT = textwrap.dedent(
f"""
-
<{TAG}>
"""
)
@classmethod
def register(cls):
viewFactory = slicer.qSlicerSingletonViewFactory()
viewFactory.setTagName(cls.TAG)
if slicer.app.layoutManager() is not None:
slicer.app.layoutManager().registerViewFactory(viewFactory)
container = cls.build(viewFactory)
layoutManager = slicer.app.layoutManager()
layoutManager.layoutLogic().GetLayoutNode().AddLayoutDescription(cls.UID, cls.LAYOUT)
return container
@classmethod
def build(cls, factory):
viewWidget = qt.QWidget()
viewWidget.setAutoFillBackground(True)
factory.setWidget(viewWidget)
viewLayout = qt.QVBoxLayout()
viewWidget.setLayout(viewLayout)
return viewWidget
@classmethod
def show(cls):
slicer.app.layoutManager().setLayout(cls.UID)
#my plot layout class
class PlotLayout(BaseLayout):
TAG = "MyPlotWidget"
UID = 1019
LAYOUT = textwrap.dedent(f"""
-
<{TAG}>
""")
lw = PlotLayout.register().layout()
PlotLayout.show()
# wrap pythonQt instance with shiboken2 (pyside2)
pysidelayout = shiboken2.wrapInstance(hash(lw), QVBoxLayout)
pg.mkQApp()
# start of pyqtgraph plotting example https://github.com/pyqtgraph/pyqtgraph/blob/master/examples/Plotting.py
win = pg.GraphicsLayoutWidget(show=True, title="Basic plotting examples")
pysidelayout.addWidget(win)
# Enable antialiasing for prettier plots
pg.setConfigOptions(antialias=True)
p1 = win.addPlot(title="Basic array plotting", y=np.random.normal(size=100))
p2 = win.addPlot(title="Multiple curves")
p2.plot(np.random.normal(size=100), pen=(255,0,0), name="Red curve")
p2.plot(np.random.normal(size=110)+5, pen=(0,255,0), name="Green curve")
p2.plot(np.random.normal(size=120)+10, pen=(0,0,255), name="Blue curve")
p3 = win.addPlot(title="Drawing with points")
p3.plot(np.random.normal(size=100), pen=(200,200,200), symbolBrush=(255,0,0), symbolPen='w')
win.nextRow()
p4 = win.addPlot(title="Parametric, grid enabled")
x = np.cos(np.linspace(0, 2*np.pi, 1000))
y = np.sin(np.linspace(0, 4*np.pi, 1000))
p4.plot(x, y)
p4.showGrid(x=True, y=True)
p5 = win.addPlot(title="Scatter plot, axis labels, log scale")
x = np.random.normal(size=1000) * 1e-5
y = x*1000 + 0.005 * np.random.normal(size=1000)
y -= y.min()-1.0
mask = x > 1e-15
x = x[mask]
y = y[mask]
p5.plot(x, y, pen=None, symbol='t', symbolPen=None, symbolSize=10, symbolBrush=(100, 100, 255, 50))
p5.setLabel('left', "Y Axis", units='A')
p5.setLabel('bottom', "Y Axis", units='s')
p5.setLogMode(x=True, y=False)
p6 = win.addPlot(title="Updating plot")
curve = p6.plot(pen='y')
data = np.random.normal(size=(10,1000))
ptr = 0
def update():
global curve, data, ptr, p6
curve.setData(data[ptr%10])
if ptr == 0:
p6.enableAutoRange('xy', False) ## stop auto-scaling after the first data set is plotted
ptr += 1
timer = QtCore.QTimer()
timer.timeout.connect(update)
timer.start(50)
win.nextRow()
p7 = win.addPlot(title="Filled plot, axis disabled")
y = np.sin(np.linspace(0, 10, 1000)) + np.random.normal(size=1000, scale=0.1)
p7.plot(y, fillLevel=-0.3, brush=(50,50,200,100))
p7.showAxis('bottom', False)
x2 = np.linspace(-100, 100, 1000)
data2 = np.sin(x2) / x2
p8 = win.addPlot(title="Region Selection")
p8.plot(data2, pen=(255,255,255,200))
lr = pg.LinearRegionItem([400,700])
lr.setZValue(-10)
p8.addItem(lr)
p9 = win.addPlot(title="Zoom on selected region")
p9.plot(data2)
def updatePlot():
p9.setXRange(*lr.getRegion(), padding=0)
def updateRegion():
lr.setRegion(p9.getViewBox().viewRange()[0])
lr.sigRegionChanged.connect(updatePlot)
p9.sigXRangeChanged.connect(updateRegion)
updatePlot()
```
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