unable to update matplotlib figure in pyqt5

[Kotaro]

I am studying MDIwindow in pyqt5 I want to update the ForcemapWidget figure when I click on the HeatmapWidget figure. However, the diagram did not update. It is confirmed that the canvas in the ForcemapWidget is updated by the print function. We know that the coordinates are also obtained. But for some reason, the chart doesn't update.

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)
        bar=self.menuBar ()

        file=bar.addMenu ("File")
        file.addAction ("New")
        file.addAction ("Cascade")
        file.addAction ("Tiled")
        file.triggered[QAction].connect (self.tritri)
        self.setWindowTitle ("MDI Application")

        # 最初のサブウィンドウを作成
        sub=QMdiSubWindow ()
        form_widget=FormWidget ()
        sub.setWidget (form_widget)
        sub.setWindowTitle ("Sub Window 1")
        self.mdi.addSubWindow (sub)
        sub.show ()
        sub2=QMdiSubWindow ()
        # ForcemapWidget.force_update ()
        form_widget=ForcemapWidget ()
        # form_widget.update()
        # print(form_widget)
        sub2.setWidget (form_widget)
        sub2.setWindowTitle ("Sub Window 2")
        self.mdi.addSubWindow (sub2)
        sub2.show()

    def tritri(self,p):
        if p.text ()=="New":
            MDIWindow.count=MDIWindow.count+1
            sub=QMdiSubWindow ()
            heatmap_widget=HeatmapWidget ()
            sub.setWidget (heatmap_widget)
            sub.setWindowTitle ("Sub Window"+str (MDIWindow.count))
            self.mdi.addSubWindow (sub)
            sub.show ()

        if p.text ()=="Cascade":
            self.mdi.cascadeSubWindows ()

        if p.text ()=="Tiled":
            self.mdi.tileSubWindows ()

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
        forcemap=ForcemapWidget (x)

class ForcemapWidget (QWidget):
    def __init__(self,x=None):
        super ().__init__ ()
        self.figure=plt.figure ()
        self.initUI (x)

    def initUI(self,x):
        self.figure.clear ()
        ax=self.figure.add_subplot (111)
        if x is not None:
            heatmap=np.random.rand (int (x),256)
        else:
            heatmap=np.random.rand (256,256)
        im=ax.imshow (heatmap,cmap = "hot")
        # self.figure.colorbar (im)
        canvas=FigureCanvas (self.figure)
        layout=QVBoxLayout ()
        layout.addWidget (canvas)
        self.setLayout (layout)
        self.update ()

    # def abc(self,x):
    #     self.x=x
    #     print(x)


class FormWidget(QWidget):
    def __init__(self):
        super().__init__()

        form_layout = QFormLayout()

        combo = QComboBox()
        combo.addItems(["Option 1", "Option 2", "Option 3"])
        form_layout.addRow("Dropdown:", combo)

        line_edit = QLineEdit()

        form_layout.addRow("Input:", line_edit)

        button = QPushButton("Submit")
        form_layout.addRow(button)

        check_box = QCheckBox()
        form_layout.addRow("Checkbox:", check_box)

        self.setLayout(form_layout)

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_()

[SGaist]

Hi and welcome to devnet,

If you are talking about the onclick method of HeatmapWidget, it just creates a local variable of type ForcemapWidget so I am unsure about what you expect there.

[Kotaro]

thank you for your reply.
I want to get coordinates on click of HeatmapWidget and change dimension of ForcemapWidget figure. How can I update the ForcemapWidget figure?
I am desperately studying object-oriented programming, so I would appreciate it if you could teach me the basics as well.

[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_()