退出后如何访问 "while True: try/break" 循环内生成的局部变量？

Question

我编写了一个模块，它获取目录中的所有 TIFF 图像，对每个图像文件中的所有帧进行平均，并将平均图像保存到由 outputPath:

指定的自动生成的子目录中

def average_tiff_frames(inputPath):
    '''
    This function opens all TIFF image files in a directory, averages over all frames within each TIFF file,
    and saves the averaged images to a subdirectory.
    
    Parameters
    ----------
    inputPath : string
        Absolute path to the raw TIFF files
    '''
    import datetime
    import os
    
    import numpy as np

    from PIL import Image
    
    
    # Read image file names, create output folder
    while True:
        try:
            inputPath = os.path.join(inputPath, '')    # Add trailing slash or backslash to the input path if missing
            filenames = [filename for filename in os.listdir(inputPath)
                            if filename.endswith(('.tif', '.TIF', '.tiff', '.TIFF'))
                            and not filename.endswith(('_avg.tif'))]
            outputPath = os.path.join(inputPath, datetime.datetime.now().strftime('%Y%m%dT%H%M%S'), '')
            os.mkdir(outputPath)
            break
        except FileNotFoundError:
            print('TIFF file not found - or - frames in TIFF file already averaged (file name ends with "_avg.tif")')

    # Open image files, average over all frames, save averaged image files
    for filename in filenames:
        img = Image.open(inputPath + filename)

        width, height = img.size
        NFrames = img.n_frames

        imgArray = np.zeros((height, width))    # Ordering of axes: img.size returns (width, height), np.zeros takes (rows, columns)
        for i in range(NFrames):
            img.seek(i)
            imgArray += np.array(img)
            i += 1
        imgArrayAverage = imgArray / NFrames

        imgAverage = Image.fromarray(imgArrayAverage)
        imgAverage.save(outputPath + filename.rsplit('.')[0] + '_avg' + '.tif')

        img.close()

    return outputPath
    print('Averaged TIFF images have been saved to ' + outputPath + '. The output path is returned as a string to the variable "outputPath".')

执行模块后，我希望 outputPath（即分配给它的字符串）可用于进一步的步骤。然而，当做

average_tiff_frames(inputPath)
print(outputPath)

我收到以下错误：

---------------------------------------------------------------------------
NameError                                 Traceback (most recent call last)
<ipython-input-5-99d0a947275c> in <module>()
      1 inputPath = '/home/user/Desktop/data/'
      2 average_tiff_frames(inputPath)
----> 3 print(outputPath)

NameError: name 'outputPath' is not defined

这里有什么问题？

我的第一个想法是 outputPath 是 while True: try 循环的局部变量，并在 break 之后被销毁，所以我在 outputPath = '' 之前实例化了一个空字符串 outputPath = ''循环，但没有帮助。

Answer 1

您不是在尝试访问循环外的变量，而是在尝试完全在方法之外访问它。该方法 returns 您要查找的值，因此将该值设置为变量：

outputPath = average_tiff_frames(inputPath)

print(outputPath)

或者直接打印出来：

print(average_tiff_frames(inputPath))

退出后如何访问 "while True: try/break" 循环内生成的局部变量？

How to access a local variable generated inside a "while True: try/break" loop after exiting it?

python

variables

scope

function

global-variables