Python不会关闭最后一个文件

Question

I created this code to get all excel files in a folder and make a csv file to every sheet in every file. This script works fine, but sometimes the last Excel file converted still locked by python on file system. Can anyone help me to understand what's happening?

import sys
from os import listdir
from os.path import isfile, join
import pandas as pd
import csv
import re

def removeEspecialCharacters(obj):
    if isinstance(obj, str) :
        retorno = re.sub('[(\x90|\x8F)]','',obj).replace("\r","").replace("\n","")
    else:
        retorno = obj
        
    return retorno

myFolder = r'C:\Users\myuser\Downloads\ConvertFilesToCsv'
myFiles = [f for f in listdir(myFolder) if isfile(join(myFolder, f))]

for x in range(len(myFiles)):   
    if (myFiles[x].lower().endswith('.xls') or myFiles[x].lower().endswith('.xlsx') or myFiles[x].lower().endswith('.xlsb')):
        print('Converting file: '+myFiles[x]);
        if (myFiles[x].lower().endswith('.xlsb')):
            file = pd.ExcelFile(myFolder+'\\'+myFiles[x], engine='pyxlsb')
        else:
            file = pd.ExcelFile(myFolder+'\\'+myFiles[x])
    
        for mySheetName in file.sheet_names:
            df = pd.read_excel(file, sheet_name=mySheetName)
            df = df.applymap(removeEspecialCharacters)
            csvFileName = myFolder+'\\'+myFiles[x].replace('.xlsx','').replace('.xlsb','').replace('.xls','')+'_'+mySheetName+'.csv'
            df.to_csv(csvFileName,encoding='utf-8-sig',index=False,sep=",",quoting=csv.QUOTE_NONNUMERIC,quotechar="\"",escapechar="\"",decimal=".",date_format='%Y-%m-%d')#,quotechar='\'', escapechar='\\')
        file.close()
        file = ''

Answer 1

Note : this is a comment putting here for code format.

Your code looks fine to me. I would advise you to use context management, similar to the doc , like this:

for filename in myFiles:   
    extension = filename.split('.')[-1]

    # you didn't seem to check xlsb in your code
    if extension not in ['xls', 'xlsx', 'xlsb']: 
        continue

    kwargs = {'engine': 'pyxlsb'} if extension=='xlsb' else {}

    with pd.ExcelFile(myFolder + '\\' + filename, **kwargs) as file:
        # do other stuff with file
        ...
        # you don't need to close file here
        # file.close()