python thread is not working. What's the solution?

Question

This Part of the code has pysimple gui applied to yolo.

I'd like to try the thread in this code,

I want to run a thread inside 'while' and print a sentence every 2.5 seconds.

However, this function does not run every 2.5 seconds, but every when loop.

What is the way to run every 2.5 seconds in while loop

import PySimpleGUIQt as sg
##########thread test########################
def print_text():
print("yolo run")

threading.Timer(2.5, print_text).start()
################################################

thread test method

# loop over frames from the video file stream
win_started = False
if use_webcam:
    cap = cv2.VideoCapture(0)
while True:
    print_text()###########################################test thread

when to declare thread function inside while loop

    # read the next frame from the file or webcam
    if use_webcam:
        grabbed, frame = cap.read()
    else:
        grabbed, frame = vs.read()

    # if the frame was not grabbed, then we have reached the end
    # of the stream
    if not grabbed:
        break

    # if the frame dimensions are empty, grab them
    if W is None or H is None:
        (H, W) = frame.shape[:2]

    # construct a blob from the input frame and then perform a forward
    # pass of the YOLO object detector, giving us our bounding boxes
    # and associated probabilities
    blob = cv2.dnn.blobFromImage(frame, 1 / 255.0, (416, 416),
        swapRB=True, crop=False)
    net.setInput(blob)
    start = time.time()
    layerOutputs = net.forward(ln)
    end = time.time()

    # initialize our lists of detected bounding boxes, confidences,
    # and class IDs, respectively
    boxes = []
    confidences = []
    classIDs = []

    
    # apply non-maxima suppression to suppress weak, overlapping
    # bounding boxes
    idxs = cv2.dnn.NMSBoxes(boxes, confidences, gui_confidence, gui_threshold)

    # ensure at least one detection exists
    if len(idxs) > 0:
        # loop over the indexes we are keeping
        for i in idxs.flatten():
            # extract the bounding box coordinates
            (x, y) = (boxes[i][0], boxes[i][1])
            (w, h) = (boxes[i][2], boxes[i][3])

            # draw a bounding box rectangle and label on the frame
            color = [int(c) for c in COLORS[classIDs[i]]]
            cv2.rectangle(frame, (x, y), (x + w, y + h), color, 2)
            text = "{}: {:.4f}".format(LABELS[classIDs[i]],
                confidences[i])
            cv2.putText(frame, text, (x, y - 5),
                cv2.FONT_HERSHEY_SIMPLEX, 0.5, color, 2)
    



    imgbytes = cv2.imencode('.png', frame)[1].tobytes()  # ditto

And the thread doesn't stop when finish the run. I'd really appreciate it if you could tell me how to stop. — LO-OmJ, Sep 23 '20 at 08:41

score 0 · Answer 1 · answered Sep 24 '20 at 12:46

Maybe you put your while loop inside the code that the thread will be executing.

import time
from threading import Thread

def print_text():
     while True:
         print('yolo run')
         time.sleep(2.5) 
# Thread waits 2.5 seconds and then return to the beginning of the while loop

For your main code

# creating thread
print_thread = threading.Thread(target=print_text(), args=(1,))
# start thread
print_thread.start()
# wait thread to finish
print_thread.join()

This code will create one single thread capable of doing your calculations until some stop condition are met.

python thread is not working. What's the solution?

1 Answers1