Error With Ipython In Showing Plots With Pyqtgraph

i have successfully installed pyqtgraph library in python 2.7. I forked latest project from GitHub and then python setup.py install. I am now trying to show plots with it. I open

Solution 1:

pyqtgraph plots functions based on PyQT GUI-based programming. So the task of displaying plots have to be treated as starting a GUI. As told above, when I feed the commands to the IPython terminal, it works out fine:

import numpy as np
import pyqtgraph as pg
import sys

x = np.random.normal(size=1000)
y = np.random.normal(size=1000)

As noted above, problem starts when i feed the line:

pg.plot(x, y, symbol='o')

To remedy this: either input these 2 lines in one go

pg.plot(x, y, symbol='o')
pg.QtGui.QApplication.exec_()

or immediately after the previous line pg.plot(x, y, symbol='o') input this line:

pg.QtGui.QApplication.exec_()

Alternatively we could use the default QT-GUI commands also. So we get correct plots even if we run this code:-

import numpy as np
import pyqtgraph as pg
from pyqtgraph.Qt import QtCore, QtGui 
import sys

x = np.random.normal(size=1000)
y = np.random.normal(size=1000)
pg.plot(x, y, symbol='o')
if sys.flags.interactive != 1ornothasattr(QtCore, 'PYQT_VERSION'):
    QtGui.QApplication.instance().exec_()

However, if one wants to avoid invoking QTGui methods explicitly, assuming one has saved the below code as xyz.py, one can run the code successfully displaying the graphics by writing on the command line: pythonw -i xyz.py. This ensures that python has been explicitly asked to run in interactive mode. pythonw is for running in windows.

import numpy as np
import pyqtgraph as pg

x = np.random.normal(size=1000)
y = np.random.normal(size=1000)
pg.plot(x, y, symbol='o')