你必须打破这个循环

import numpy as np
import cv2
import logging as log

cap = cv2.VideoCapture('5.mpg')

while True:

    ret, image = cap.read()

    if ret == True:
        log.warning('Camera Opened Successfully')
        break

您需要中断while循环，同样由于您希望在ret为True时立即中断循环，因此可以用途：

ret = False
while not ret:

    ret, image = cap.read()

    if ret:
        log.warning('Camera Opened Successfully')
    # any other code

设置一个标志以触发日志，然后将其设置为false。当准备退出循环时，将ret设置为False，以便它退出

import numpy as np
import cv2
import logging as log

cap = cv2.VideoCapture('5.mpg')
ret = True
logit = True
while ret:

    ret, image = cap.read()

    if logit == True:
        log.warning('Camera Opened Successfully')
        logit = False

    gray = cv2.cvtColor(image, cv2.COLOR_BGR2GRAY)
    clahe = cv2.createCLAHE(clipLimit = 15.0, tileGridSize=(8,8))
    gray1 = clahe.apply(gray)
    // process remainder of situation setting

另一种可能性是利用Python中默认的可变参数：

def print_once(string, bucket=[]):
    """
    Print only one time

    >>> print_once("foo")
    foo
    >>> print_once("foo")
    """
    if string not in bucket:
        print(string)
        bucket.append(string)

假设你想用你的主循环来处理你的应用程序逻辑，并且用一个循环来检测它是否被打开，用另一个循环来处理它是没有意义的，那么我认为你想做的是设置一个变量来确定状态是否已经改变。

import numpy as np
import cv2
import logging as log

cap = cv2.VideoCapture('5.mpg')
old_ret = False

while True:

    ret, image = cap.read()

    if old_ret == False and ret == True:
        old_red = True
        log.warning('Camera Opened Successfully')

    if ret == True:
        # Do other things that need the camera but no log

import numpy as np
import cv2
import logging as log

cap = cv2.VideoCapture('5.mpg')
hasOpened = False

while True:

    ret, image = cap.read()

    if ret and not hasOpened:
        log.warning('Camera Opened Successfully')
        hasOpened = True

如果您想在打印后跳出循环，请按照Matt的答案操作。此选项将在循环中继续，并且只打印一次。

添加一个额外的布尔值来跟踪您以前是否打印过它：

import numpy as np
import cv2
import logging as log

cap = cv2.VideoCapture('5.mpg')
printed = False

while True:

    ret, image = cap.read()

    if ret == True and not printed:
        log.warning('Camera Opened Successfully')
        printed = True