如何跳过序列的其余部分

Question

I have a couple of functions that are being called recursively inside nested loops. The ultimate objective of my program is to:

a) loop through each year,
b) within each each year, loop through each month (12 total),
c) within each month, loop through each day (using a self generated day counter),
d) and read 2 files and merge them together into a another file.

In each instance, I am going down into the directory only if exists. Otherwise, I'm to just skip it and go to the next one. My code does a pretty good job when all the files are present, but when one of the files is missing, I would like to just simply skip the whole process of creating a merged file and continue the loops. The problem I am getting is a syntax error that states that continue is not properly in the loop. I am only getting this error in the function definitions, and not outside of them.

Can someone explain why I'm getting this error?

import os, calendar

file01 = 'myfile1.txt'
file02 = 'myfile2.txt'
output = 'mybigfile.txt'

def main():
    #ROOT DIRECTORY
    top_path = r'C:\directory'    
    processTop(top_path)

def processTop(path):
    year_list = ['2013', '2014', '2015']

    for year in year_list:
        year_path = os.path.join(path, year)
        if not os.path.isdir(year_path):  
            continue
        else:
            for month in range(1, 13):
                month_path = os.path.join(year_path, month)
                if not os.path.isdir(month_path):
                    continue
                else:
                    numDaysInMth = calendar.monthrange(int(year), month)[1]
                    for day in range(1, numDaysInMth+1):
                        processDay(day, month_path)
    print('Done!')


def processDay(day, path):
    day_path = os.path.join(path, day)
    if not os.path.isdir(day_path):
        continue
    else:
        createDailyFile(day_path, output)


def createDailyFile(path, dailyFile):
    data01 = openFile(file01, path)
    data02 = openFile(file02, path)

    if len(data01) == 0 or len(data02) == 0: 
        # either file is missing
        continue
    else:
        # merge the two datalists into a single list
        # create a file with the merged list
        pass

def openFile(filename, path):
    # return a list of contents of filename
    # returns an empty list if file is missing
    pass

if __name__ == "__main__": main()

Answer 1

You are probably getting that error in processDay and createDailyFile , right? That's because there is no loop in these functions, and yet you use continue . I'd recommend using return or pass in them.

Answer 2

当错误消息表明如果函数的结构如您所显示的那样，仅可以使用pass ， continue语句仅在循环中适用。

Answer 3

continue can only appear in a loop since it tells python not to execute the lines below and go to the next iteration. Hence, this syntax here is not valid :

def processDay(day, path):
    day_path = os.path.join(path, day)
    if not os.path.isdir(day_path):
        continue # <============ this continue is not inside a loop !
    else:
        createDailyFile(day_path, output)enter code here

Same for your createDailyFile function.

You may want to replace it with a return ?

Answer 4

You can use continue only plainly inside a loop (otherwise, what guarantee you have that the function was called in a loop in the first place?) If you need stack unwinding, consider using exceptions ( Python exception handling ).

I think you can get away with having your functions return a value that would say if operation was completed successfully:

def processDay(day, path):
  do_some_job()
  if should_continue:
     return False
  return True

And then in your main code simply say

if not processDay(day, path):
  continue