[FIXED] How to update Progressbar in PyQT through QThread which calls another function

Issue

I am quite new to PyQT. I am learning how to make a Progressbar and update it as my algorithm progresses. I have been able to make a Basic Progressbar that updates itself using this link: Python pyqt pulsing progress bar with multithreading

The problem is, I need to do the same for my algorithm and that algorithm has a different function and can not be written inside the run function of QThread.

This is my code for the QThread class, (same as given in above link)

class External(QThread):

    countChanged = pyqtSignal(int)
    
    def run(self):
        count = 0 
        while count < 100:
            count += 1
            time.sleep(1)
            self.countChanged.emit(count)

And this is the code for my Progressbar,

def generate_timetable(self):
        self.calc = External() 
        self.calc.countChanged.connect(self.onCountChanged)
        self.calc.start()
    
    def onCountChanged(self, value):
        self.ui.progressBar.setValue(value)

Now, this is kind of a pseudocode of my algorithm function (this function will basically replace the time.sleep(1) function)

def algorithm():

    fh = False
    best_solution = None
    count = 1 
    best_fitness = 100000 # any huge number  
    while fh is False:
        fh = True
        solution, solution_fitness = another_function() 
        if solution_fitness < best_fitness:
            best_solution = solution 
            best_fitness = solution_fitness 
            fh = False
        
        print("ITERATION #", count, " is OVER!")
        print("Best Solution FItness: ", best_fitness)
        count += 1 
    
    return best_solution, best_fitness

What I need to do is after every iteration, my Thread class emits a signal and the best solution's fitness value is printed on my main GUI (I have a label for that) and Progressbar's value is also updated (let's say I want it to update by 1 count only, just like it is being done in the current program)

The problem however is this that I can't return the fitness value after one iteration, because if I do that, my algorithm will need to be restarted and hence I will lose my progress. But without returning the value from the function, I don't know how can I possibly know that one iteration is over so now emit the signal, update the progressbar value and also set the label value to the fitness value calculated after the iteration.

Can anyone guide me regarding this? or show me any project that has something similar to this.

Solution

I think you can get what you want by just changing your signal from pyqtSignal(int) to pyqtSignal(int, int) and then within your algorithm loop self.countChanged.emit(count, best_fitness). You could also define a second signal for the fitness if you want them separate.

Answered By - shao.lo