Python 将 Pandas 列转换为日期时间
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Convert Pandas Column to DateTime
提问by Chris
I have one field in a pandas DataFrame that was imported as string format. It should be a datetime variable. How do I convert it to a datetime column and then filter based on date.
我在以字符串格式导入的 Pandas DataFrame 中有一个字段。它应该是一个日期时间变量。如何将其转换为日期时间列，然后根据日期进行过滤。
Example:
例子：
- DataFrame Name: raw_data
- Column Name: Mycol
- Value Format in Column: '05SEP2014:00:00:00.000'
- 数据帧名称：raw_data
- 列名：Mycol
- 列中的值格式：'05SEP2014:00:00:00.000'
采纳答案by chrisb
Use the to_datetimefunction, specifying a formatto match your data.
使用该to_datetime函数，指定一种格式以匹配您的数据。
raw_data['Mycol'] = pd.to_datetime(raw_data['Mycol'], format='%d%b%Y:%H:%M:%S.%f')
回答by mechanical_meat
You can use the DataFrame method .apply()to operate on the values in Mycol:
您可以使用 DataFrame 方法.apply()对Mycol 中的值进行操作：
>>> df = pd.DataFrame(['05SEP2014:00:00:00.000'],columns=['Mycol'])
>>> df
Mycol
0 05SEP2014:00:00:00.000
>>> import datetime as dt
>>> df['Mycol'] = df['Mycol'].apply(lambda x:
dt.datetime.strptime(x,'%d%b%Y:%H:%M:%S.%f'))
>>> df
Mycol
0 2014-09-05
回答by Darth BEHFANS
raw_data['Mycol'] = pd.to_datetime(raw_data['Mycol'], format='%d%b%Y:%H:%M:%S.%f')
works, however it results in a Python warning of
A value is trying to be set on a copy of a slice from a DataFrame.
Try using .loc[row_indexer,col_indexer] = valueinstead
工作，但是它会导致 Python 警告 A value is试图设置在来自 DataFrame 的切片的副本上。尝试.loc[row_indexer,col_indexer] = value改用
I would guess this is due to some chaining indexing.
我猜这是由于一些链接索引。
回答by Vlad Bezden
If you have more than one column to be converted you can do the following:
如果要转换的列不止一列，则可以执行以下操作：
df[["col1", "col2", "col3"]] = df[["col1", "col2", "col3"]].apply(pd.to_datetime)
回答by Prateek Sharma
Use the pandas to_datetimefunction to parse the column as DateTime. Also, by using infer_datetime_format=True, it will automatically detect the format and convert the mentioned column to DateTime.
使用 pandasto_datetime函数将列解析为 DateTime。此外，通过使用infer_datetime_format=True，它会自动检测格式并将提到的列转换为日期时间。
import pandas as pd
raw_data['Mycol'] = pd.to_datetime(raw_data['Mycol'], infer_datetime_format=True)
