关闭文件上的 Python ValueError I/O 操作
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Python ValueError I/O operation on closed file
提问by Duy Bui
I know this sounds a common error which has been asked multiple times on stackoverflow. However, I am pretty sure my issue is new as I read through almost the related topics.
我知道这听起来是一个常见的错误，在 stackoverflow 上被多次询问过。但是，我很确定我的问题是新的，因为我几乎通读了相关主题。
I have two files as follows:
我有两个文件如下：
ALL_USER_PATH = 'all.csv'
NEW_USER_PATH = 'new.csv'
I open the "all" file for reading first
我先打开“所有”文件进行阅读
with open(ALL_USER_PATH, "r") as f:
df = pd.read_csv(f) #pd is pandas
f.close()
Next, I delete the content of the "new" file and get ready to write new data to it
接下来，我删除“新”文件的内容并准备向其中写入新数据
if os.path.isfile(NEW_USER_PATH):
os.remove(NEW_USER_PATH)
Write to it and it works fine
写信给它，它工作正常
with open(NEW_USER_PATH, "a") as csv_n:
#writer_n is to write new users
writer_n = csv.writer(csv_n, delimiter=",", lineterminator='\n')
for user in customer_records:
if checkExistence(df): # a method I wrote before
continue
else:
writer_n.writerow([data_to_be_written])
Next, I delete the "all" file and write new data to it
接下来，我删除“所有”文件并向其写入新数据
if os.path.isfile(ALL_USER_PATH):
os.remove(ALL_USER_PATH)
with open(ALL_USER_PATH, "a") as csv_a:
writer_a = csv.writer(csv_n, delimiter=",", lineterminator='\n')
for user in customer_records:
writer_a.writerow([all_data_to_be_written])
The error
错误
"ValueError i/o operation on closed file"
“关闭文件上的 ValueError i/o 操作”
is thrown herein at the last line to write data to the "all" file. I think it is because I opened it before, but I do remember to close it after reading the data, don't I? Could somebody please let me know what the problem is?
在最后一行抛出这里将数据写入“所有”文件。我想是因为我之前打开过它，但我确实记得在阅读数据后关闭它，不是吗？有人可以让我知道问题是什么吗？
回答by TheOneWhoLikesToKnow
I also had that error but found another question with an answer and it worked.
我也有这个错误，但找到了另一个有答案的问题，它奏效了。
After you leave the indented block under with open (csv file.csv) as csv:it will close the file.
在您离开缩进块后with open (csv file.csv) as csv:，它将关闭文件。
with open('ALL_USER_PATH','a') as csv_a:
writer_a = csv.writer(csv_n, delimiter=",", lineterminator='\n')
# Here the file stays open
# Here the file is closed
I hope I managed to help.
我希望我能帮上忙。
