pandas 使用pandas.to_csv到YYYY-MM-DD时如何指定日期格式？
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How to specify date format when using pandas.to_csv to YYYY-MM-DD?
提问by NumenorForLife
The OP of this posthighlighted the lack of documentation for using the date_format argument in pandas. I would like to format the data into YYYY-MM-DD, not MM/DD/YYYY when using the to_csv command.
这篇文章的 OP强调了在Pandas中使用 date_format 参数的文档的缺乏。我想在使用 to_csv 命令时将数据格式化为 YYYY-MM-DD，而不是 MM/DD/YYYY。
I've tried: frame.to_csv(output_dir, index=False, encoding='utf-8', date_format='%Y-%m-%d')and it is not working, where frame is a DataFrame
我试过：frame.to_csv(output_dir, index=False, encoding='utf-8', date_format='%Y-%m-%d')它不工作，其中 frame 是一个 DataFrame
The file I'm trying to convert can be found here
可以在此处找到我要转换的文件
回答by EdChum
This is already supported in to_csvas a param date_format:
这已经to_csv作为 param支持date_format：
t="""date,val
12/05/1984,sadas
1/11/1980,sadas
2/4/1945,sadas
22/10/1921,sadas"""
df = pd.read_csv(io.StringIO(t), parse_dates=[0])
df.to_csv(r'c:\data\date.csv', date_format='%Y-%m-%d')
Yields:
产量：
,date,val
0,1984-12-05,sadas
1,1980-01-11,sadas
2,1945-02-04,sadas
3,1921-10-22,sadas
The format strings are of the form taken from strftime
格式字符串的格式取自 strftime
回答by Nicholas Aldershof
You can use the standard datetime string formatting behavior, here that would be: df.to_csv('df.csv, date_format="%Y-%m-%d") https://docs.python.org/2/library/datetime.html#strftime-strptime-behavior
您可以使用标准的日期时间字符串格式化行为，这里是： df.to_csv('df.csv, date_format="%Y-%m-%d") https://docs.python.org/2/library /datetime.html#strftime-strptime-behavior
EDIT: don't iterate through the dataframe with strftime, that's highly unoptimized and theres already a built-in function for performing the operation you want
编辑：不要使用 strftime 遍历数据帧，这是高度未优化的，并且已经有一个内置函数来执行您想要的操作
