Python3 "If" 没有捕捉到正在检查的内容

Question

我已经查看了其他问题，例如 (Python 'if x is None' not catching NoneType)，但我没有发现这些信息对我的场景有用。

    import pyautogui

##########################
#This is a looping routine to search for the current image and return its coordinates 
##########################

def finder(passedImage, workSpace): #start the finder func
    print (passedImage) #print the image to be found
    currentImage = pyautogui.locateOnScreen(passedImage,region=(workSpace),  grayscale=True) #search for the image on the screen
    if currentImage == None: # if that initial search goes "none" ...
        print ("Looking") #Let us know we are looking
        finder(passedImage,workSpace) #go and do the function again
    print(currentImage) #print out the coordinates
    currentImageX, currentImageY = pyautogui.center(currentImage) #get the X and Y coord
    pyautogui.click(currentImageX, currentImageY) #use the X and Y coords for where to click
    print(currentImageX, currentImageY) #print the X and Y coords

脚本的想法很简单。它只是找到图像的坐标，然后使用 pyautogui 库单击它（模块？对我来说是新术语）

除 "if currentImage == None:" 位外，一切正常。

它有时会在 currentImage 为 None 时捕获，然后适当地重新运行该函数以获取它，但有时它不会。我似乎无法找到它背后的任何韵律或原因，有时有效，有时无效。

任何关于我如何检查 None 然后回应存在 None 的建议都很棒 :)

抛出的示例错误如下：

Traceback (most recent call last):
File "fsr_main_001.py", line 57, in <module>
newItem()
File "fsr_main_001.py", line 14, in newItem
finder.finder(passedImage,workSpace)
File "/home/tvorac/python/formAutomation/finder.py", line 14, in finder
currentImageX, currentImageY = pyautogui.center(currentImage) #get the X and Y coord
File "/usr/local/lib/python3.5/dist-packages/pyscreeze/__init__.py", line 398, in center
return (coords[0] + int(coords[2] / 2), coords[1] + int(coords[3] / 2))
TypeError: 'NoneType' object is not subscriptable

Answer 1

我认为发生的事情是当你说你重新运行这个函数时，你是在递归地这样做。新调用 finder 后没有 return:

if currentImage == None: # if that initial search goes "none" ...
    print ("Looking") #Let us know we are looking
    finder(passedImage,workSpace) #go and do the function again
print(currentImage) #print out the coordinates

一旦 finder() 调用完成它的工作，控制 returns 到 currentImage 是 None 的函数实例，它继续打印, pyautogui.center 等等。

考虑到这可能会导致一些相当深的递归，它可能不是查找图像的最佳方法。相反，某种循环是最好的。

currentImage = None
while currentImage is None:
    currentImage = pyautogui.locateOnScreen(passedImage,region=(workSpace), grayscale=True) #search for the image on the screen

（或类似的东西，添加超时、最大重试次数等）

Python3 "If" 没有捕捉到正在检查的内容

Python3 "If" not catching what it is checking

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typeerror

nonetype

pyautogui