如何在Qt小部件中显示matplotlib.pyplot？

Question

I want to show the pyplot image in widget (QWidget) that I put in a gui designed in QtDesigner:

When I push the Çiz button I want to show the image that I can create in python with that code:

points = np.array([(1, 1), (2, 4), (3, 1), (9, 3)])

x = points[:,0]
y = points[:,1]
# calculate polynomial
z = np.polyfit(x, y, 2)
f = np.poly1d(z)

x_fit = np.linspace(min(x), max(x), 10000)
y_fit = [f(_x) for _x in x_fit]

plt.plot(x, y)
plt.plot(x_fit, y_fit)
plt.show()

EDIT

I made some changes according to the answer but I have new problems.

After I promote it:

I rearrange my code below:

# calculate polynomial and r
self.x_fit = np.linspace(min(self.itemX), max(self.itemY), 10000)
self.y_fit = [f(_x) for _x in self.x_fit]

self._dlg.plotwidget.plot(self.itemX, self.itemY)
self._dlg.plotwidget.plot(self.x_fit, self.y_fit)

self.itemX is x values in a list.

self.itemY is y values in a list.

self._dlg is the MainWindow that you see.

When I try to open that window I get this error message:

Answer 1

Sorry I don't exactly answer the question but I don't use matplotlib.pyplot with pyqt. I recommend using pyqtgraph ( http://pyqtgraph.org ), which is quite convenient and powerful. With Qt Designer:

• you just insert a 'graphics view' in your GUI
• you right-click on it and promote it to "plotwidget" using pyqtgraph. I guess the english tab is something like this: base class 'QGraphicsView'; promoted class 'PlotWidget'; header file 'pyqtgraph', then 'add', then 'promote'
• then you can make plotwidget.plot(x,y,...), plotwidget.clear(), and co. It will plot everything inside the plotwidget with a bunch of interacting possibilities

Answer 2

I just tested the code below works for me:

import sys
import numpy as np
import pyqtgraph as pg
from pyqtgraph.Qt import QtCore, QtGui, uic
uifilename = 'test.ui'
form_class = uic.loadUiType(uifilename)[0] #dirty reading of the ui file. better to convert it to a '.py'

class MyWindowClass(QtGui.QMainWindow, form_class):

    def __init__(self):
        QtGui.QMainWindow.__init__(self)
        self.setupUi(self)
        self.onInit()

    def onInit(self):
#usually a lot of connections here
        self.x_fit = np.linspace(1,10000, 10000)
        self.y_fit = [f(_x) for _x in self.x_fit]
        self.plotwidget.plot(self.x_fit,self.y_fit,symbol='o',pen=None)
        self.plotwidget.setLabel('left',text='toto',units='')
        self.plotwidget.setLabel('top',text='tata',units='')

def f(x):
    return x**2+1

if __name__ == '__main__':
    if (sys.flags.interactive != 1) or not hasattr(QtCore, 'PYQT_VERSION'):
        app = QtGui.QApplication([])
        pg.setConfigOption('background', 'w') 
        win = MyWindowClass()
        win.show()
        app.exec_()

with this test.ui : https://github.com/steph2016/profiles/blob/master/test.ui . Note the plotwidget is encapsulated inside a layout. I thought it works with just the Main Window, but I'm not sure anymore...