unable to update matplotlib figure in pyqt5

SGaist

@Kotaro your widget has self.forcemapWidget, that's the one you want to update.

Kotaro

@SGaist Yes, that's right. As a beginner, I had to wait 600 seconds.

SGaist

Since your issue is solved, please mark the thread as solved using the "Topic Tools" button or the three dotted menu beside the answer you deem correct so other forum members may know a solution has been found :-)

Kotaro

@SGaist I’m sorry.
I don't know where to fix the code.

SGaist

Use self.forcemapWidget in onclick.

Kotaro

@SGaist

   def onclick(self,event):
        x,y=event.xdata,event.ydata
        forcemap=self.forcemapWidget (x)

このようにしても更新できません。
何回もすみません。

SGaist

@Kotaro you should add a method to the ForcemapWidget class that takes that x value and do the required update.

Kotaro

@SGaist
Isn't it def initUI in class ForcemapWidget?
Is it wrong?
maybe i don't understand the basics

SGaist

Sorry for being blunt but yes you are. Updating a widget by recreating it every time you want to change a value is wrong.

initUI should be used once at construction time to put the various pieces in place. You should then have a separate function that take that x value and update the canvas content however you see fit. Such a method can also be called from the initUI method.

Kotaro

@SGaist Thank you for your kindness
I thought I could update it by recreating the widget each time I changed the value.
How should I write the update function?
Do you have any examples?

Kotaro

@SGaist
I changed it like this but it doesn't work.

class HeatmapWidget(QWidget):
    def __init__(self):
        super().__init__()
        self.forcemapWidget=ForcemapWidget()
        fig,ax=plt.subplots (figsize = (1,1))

        heatmap=np.random.rand (256,256)
        im=ax.imshow (heatmap,cmap = "hot")
        fig.colorbar (im)
        ax.set_title ("Heatmap")
        fig.canvas.mpl_connect ("button_press_event",self.onclick)

        canvas=FigureCanvas (fig)
        layout=QVBoxLayout ()
        layout.addWidget (canvas)
        self.setLayout (layout)

    def onclick(self, event):
        x, y = event.xdata, event.ydata
        self.forcemapWidget.click(x)


class ForcemapWidget (QWidget):
    def __init__(self):
        super ().__init__ ()
        self.figure=plt.figure ()
        self.ax=self.figure.add_subplot (111)
        heatmap=np.random.rand (256,256)
        self.im=self.ax.imshow (heatmap,cmap = "hot")
        canvas=FigureCanvas (self.figure)
        layout=QVBoxLayout ()
        layout.addWidget (canvas)
        self.setLayout (layout)

    def click(self,x):
        self.figure=plt.figure ()
        self.ax=self.figure.add_subplot (111)
        heatmap=np.random.rand (int (x),256)
        self.im=self.ax.imshow (heatmap,cmap = "hot")
        canvas=FigureCanvas (self.figure)
        layout=QVBoxLayout ()
        layout.addWidget (canvas)
        self.setLayout (layout)
        self.update()

SGaist

You are rebuilding the whole widget and likely are getting warnings on the terminal.

Please take the time to learn how matplotlib works. What you have to do is update the plot and refresh the canvas.

Kotaro

@SGaist I can understand by looking at the example that I am doing the mouse events in one class.
I'm confused because there is no example of mouse events between two classes
Do you have a simple example?

SGaist

You handling the click event of your canvas, not multiple widgets. The fact that you called all methods click or onclick does not mean they are click event handler.

You really should use meaningful name for your methods and variables. That will make your code easier to follow and reason about.

Kotaro

@SGaist
I made one that updates the color when clicked, but it doesn't.
Do you know why?

import numpy as np
import matplotlib.pyplot as plt
from PyQt5.QtWidgets import QVBoxLayout,QApplication,QWidget,QMainWindow,QMdiArea,QAction,QMdiSubWindow,QTextEdit, \
   QComboBox,QLineEdit,QPushButton,QCheckBox,QFormLayout
import sys
from matplotlib.backends.backend_qt5agg import FigureCanvasQTAgg as FigureCanvas

class MDIWindow (QMainWindow):
   count=0
   def __init__(self):
       super ().__init__ ()
       self.mdi=QMdiArea ()
       self.setCentralWidget (self.mdi)
       self.setWindowTitle ("MDI Application")
       sub2=QMdiSubWindow ()
       form_widget=ForcemapWidget ()
       sub2.setWidget (form_widget)
       sub2.setWindowTitle ("Sub Window 2")
       self.mdi.addSubWindow (sub2)
       sub2.show()
       sub3=QMdiSubWindow ()
       form_widget=HeatmapWidget ()
       sub3.setWidget (form_widget)
       sub3.setWindowTitle ("Sub Window 2")
       self.mdi.addSubWindow (sub3)
       sub3.show()
class HeatmapWidget(QWidget):
   def __init__(self,parent=None):
       super().__init__()
       # self.forcemapWidget=ForcemapWidget()
       fig,ax=plt.subplots (figsize = (1,1))
       heatmap=np.random.rand (256,256)
       im=ax.imshow (heatmap,cmap = "hot")
       fig.colorbar (im)
       ax.set_title ("Heatmap")
       fig.canvas.mpl_connect ("button_press_event",self.onclick)
       canvas=FigureCanvas (fig)
       layout=QVBoxLayout ()
       layout.addWidget (canvas)
       self.setLayout (layout)
   def onclick(self, event):
       self.force=ForcemapWidget()
       self.force.updates()
class ForcemapWidget(QWidget):
   def __init__(self):
       super().__init__()
       self.figure = plt.figure(figsize=(5, 4))
       ax = self.figure.add_subplot(111)
       heatmap = np.random.rand(256, 256)
       self.im = ax.imshow(heatmap, cmap="Oranges")
       self.colorbar = self.figure.colorbar(self.im)
       canvas = FigureCanvas(self.figure)
       layout = QVBoxLayout()
       layout.addWidget(canvas)
       self.setLayout(layout)
   def updates(self):
       self.im.set_cmap("Blues")
       self.figure.canvas.draw()
app = QApplication(sys.argv)
mdi = MDIWindow()
mdi.show()
app.exec_()

Kotaro

I understand this.
Here is the code as an example.

import numpy as np
import matplotlib.pyplot as plt
from PyQt5.QtWidgets import QVBoxLayout,QApplication,QWidget,QMainWindow,QMdiArea,QAction,QMdiSubWindow,QTextEdit, \
   QComboBox,QLineEdit,QPushButton,QCheckBox,QFormLayout
import sys
from matplotlib.backends.backend_qt5agg import FigureCanvasQTAgg as FigureCanvas

class MDIWindow (QMainWindow):
   count=0
   def __init__(self):
       super ().__init__ ()
       self.mdi=QMdiArea ()
       self.setCentralWidget (self.mdi)
       self.setWindowTitle ("MDI Application")
       sub2=QMdiSubWindow ()
       form_widget=ForcemapWidget ()
       sub2.setWidget (form_widget)
       sub2.setWindowTitle ("Sub Window 2")
       self.mdi.addSubWindow (sub2)
       sub2.show ()
       sub3 = QMdiSubWindow()
       form_widget = HeatmapWidget(forcemap_widget=form_widget)
       sub3.setWidget(form_widget)
       sub3.setWindowTitle("Sub Window 3")
       self.mdi.addSubWindow(sub3)
       sub3.show()
class HeatmapWidget(QWidget):
   def __init__(self, forcemap_widget, parent=None):
       super().__init__()
       self.forcemap_widget = forcemap_widget  
       fig,ax=plt.subplots (figsize = (1,1))
       heatmap=np.random.rand (256,256)
       im=ax.imshow (heatmap,cmap = "hot")
       fig.colorbar (im)
       ax.set_title ("Heatmap")
       fig.canvas.mpl_connect ("button_press_event",self.onclick)
       self.canvas=FigureCanvas (fig)
       layout=QVBoxLayout ()
       layout.addWidget (self.canvas)
       self.setLayout (layout)
   def onclick(self, event):
       x, y = event.xdata, event.ydata
       self.forcemap_widget.updates()  # 正
class ForcemapWidget(QWidget):
   def __init__(self):
       super().__init__()
       self.figure = plt.figure(figsize=(5, 4))
       ax = self.figure.add_subplot(111)
       heatmap = np.random.rand(256, 256)
       self.im = ax.imshow(heatmap, cmap="Oranges")
       self.colorbar = self.figure.colorbar(self.im)
       self.canvas = FigureCanvas(self.figure)
       layout = QVBoxLayout()
       layout.addWidget(self.canvas)
       self.setLayout(layout)
   def updates(self):
       self.im.set_cmap("Blues")
       self.figure.canvas.draw()
       # self.show()
app = QApplication(sys.argv)
mdi = MDIWindow()
mdi.show()
app.exec_()