How Can I Use DateAxisItem Of PyQtGraph?

I'm using PyQtGraph '0.9.8+gd627e39' on Python 3.6.2(32bit) and Windows 10. My goal is to plot real time data with an X-axis that shows datetime. Time

Solution 1:

Based on a previous answer, the plot in pyqtgraph only accept data of numerical type so you must convert it and for this case we use timestamp(), then in a custom AxisItem we convert it to string to show it with the help of fromtimestamp.

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


class TimeAxisItem(pg.AxisItem):
    def tickStrings(self, values, scale, spacing):
        return [datetime.fromtimestamp(value) for value in values]

list_x = [datetime(2018, 3, 1, 9, 36, 50, 136415), 
        datetime(2018, 3, 1, 9, 36, 51, 330912),
        datetime(2018, 3, 1, 9, 36, 51, 382815),
        datetime(2018, 3, 1, 9, 36, 52, 928818)]

list_y = [10, 9, 12, 11]

app = QtGui.QApplication([])

date_axis = TimeAxisItem(orientation='bottom')
graph = pg.PlotWidget(axisItems = {'bottom': date_axis})

graph.plot(x=[x.timestamp() for x in list_x], y=list_y, pen=None, symbol='o')
graph.show()

if __name__ == '__main__':
    import sys
    if (sys.flags.interactive != 1) or not hasattr(QtCore, 'PYQT_VERSION'):
        QtGui.QApplication.instance().exec_()