在函数中定义变量时名称定义错误

Question

我有一段代码接受带有文件名列表的 .csv 作为输入，然后将文件名分解为其组成部分，并将它们与一些其他字符一起重新排序。

输入示例：

3006419_3006420_ENG_FRONT.jpg

输出示例：

;E3006419_3006420_FRONT_Image_Container;

但是，我想将 for 循环中将文件名拆分为一个函数，以便我可以在其他地方调用，这样我就可以在第二个 for 循环中重新使用它，该循环以不同的格式输出.但是，当我尝试定义一个函数时，我的变量似乎存在范围错误，无法在 output.write 语句中使用它们。

工作代码

from csv import reader
import sys

if len(sys.argv) != 2:
    print('USAGE ERROR:\nRun like "python <script.py> <input file.csv>"') #error message if code is not run with correct number of arguments
    exit()

file = open(sys.argv[1]) #open input file
output = open('output.impex','w+') #define output impex file

for line in file:
    nameAndExtension = line.split('.') #split file into filename and file extension
    name = nameAndExtension[0] 
    extension = nameAndExtension[1].replace('\n','') #save file extension as variable extension and remove \n
    elements = name.split('_') #split filename into constituent elements. Filenames are formatted as PARENTSKU_CHILDSKU_LANG_ANGLE.extension, eg '3006419_3006420_ENG_FRONT.jpg'
    parentSKU = elements[0]
    childSKU = elements[1]
    lang = elements[2]
    angle = elements[3]

    output.write(";E" + parentSKU + "_" + childSKU + "_" + angle + '_Image_Container;\n') 

非工作代码：

from csv import reader
import sys

if len(sys.argv) != 2:
    print('USAGE ERROR:\nRun like "python <script.py> <input file.csv>"') #error message if code is not run with correct number of arguments
    exit()

file = open(sys.argv[1]) #open input file
output = open('output.impex','w+') #define output impex file

def lineSplitting(x):
    nameAndExtension = x.split('.') #split file into filename and file extension
    name = nameAndExtension[0] 
    extension = nameAndExtension[1].replace('\n','') #save file extension as variable extension and remove \n
    elements = name.split('_') #split filename into constituent elements. Filenames are formatted as PARENTSKU_CHILDSKU_LANG_ANGLE.extension, eg '3006419_3006420_ENG_FRONT.jpg'
    parentSKU = elements[0]
    childSKU = elements[1]
    lang = elements[2]
    angle = elements[3]

for line in file:
    lineSplitting(line)
    output.write(";E" + parentSKU + "_" + childSKU + "_" + angle + '_Image_Container;\n') 

我收到“NameError: name 'parentSKU' is not defined”我认为因为变量范围的原因 - 但我不知道我需要做什么才能使变量可重用在for循环中。我需要做什么才能将所有拆分和变量定义变成一个函数？

Answer 1

你应该从函数中返回你的值

def lineSplitting(x):
    nameAndExtension = x.split('.') #split file into filename and file extension
    name = nameAndExtension[0] 
    extension = nameAndExtension[1].replace('\n','') #save file extension as variable extension and remove \n
    elements = name.split('_') #split filename into constituent elements. Filenames are formatted as PARENTSKU_CHILDSKU_LANG_ANGLE.extension, eg '3006419_3006420_ENG_FRONT.jpg'
    parentSKU = elements[0]
    childSKU = elements[1]
    lang = elements[2]
    angle = elements[3]

    return parentSKU,childSKU,angle 

接下来的代码会调用函数

for line in file:
    parentSKU,childSKU,angle =lineSplitting(line)
    output.write(";E" + parentSKU + "_" + childSKU + "_" + angle + '_Image_Container;\n')