How to load large pkl file in pytq window?

Question

I have to load very huge pandas dataframe stored in a local HDD when PyQt GUI is loaded.

The problem is, GUI window hangs until loading huge file is finished.

The below is my sample code.

I think my hanging problem can be solved by using thread and progressbar window.

But, most thread examples I found are using global functions and variables.

In my situation, self.pkl.file should have loaded data. So I should find proper way to toss instance to thread class/function.

I hope you to introduce several sample code or guideline for my situation.

Thank you in advance.

#!/usr/bin/python 
# -*- coding: utf-8 -*- 

import sys 
from PyQt4 import QtGui 
import pandas as pd 

class Pkl(): 
    def __init__(self): 
        self.file = pd.read_pickle('file.dat') 


class MyWindow(QtGui.QMainWindow): 
    def __init__(self, parent=None): 
        super(MyWindow, self).__init__(parent) 

        self.setWindowTitle('MyWindow') 
        self.show() 
        self.pkl = Pkl() 
    def close_application(self): 

        self.close() 




def main(): 

    app = QtGui.QApplication(sys.argv) 
    GUI = MyWindow() 

    ''' 
    w = QtGui.QWidget() 
    w.resize(250, 150) 
    w.move(300, 300) 
    w.setWindowTitle('Simple') 
    w.show() 
    ''' 

    sys.exit(app.exec_()) 


if __name__ == '__main__': 
    main()

Answer 1

You need should use QtCore.QThread, on your case pass it the "pkl" object that should be read on the threading code. Then you need to emit a signal from your thread when the read is complete. That signal is connected to your main class/main thread, which will have access to the pkl object and can update the GUI as required.

For the code check. Updating GUI elements in MultiThreaded PyQT