如何将 pandas 时间戳更改为 python 日期时间对象？

Question

我正在寻找一种方法将 pandas 时间戳更改为 python 日期时间对象，但我失败了。我用了 to_pydatetime().

下面是我的代码和注释：

import pandas
import datetime
import pytz

forced_UTC = pytz.timezone("Europe/London").localize(datetime.datetime(2019, 1, 30, 9, 5)).tzinfo
forced_BST = pytz.timezone("Europe/London").localize(datetime.datetime(2019, 4, 27, 9, 5)).tzinfo
#print (forced_UTC, forced_BST)

# Create dataframe and check the value of the first element in the column.
my_df = pandas.DataFrame({"my_column": ["2019-04-01 00:15:00", "2019-02-23 13:00:00", "2019-02-23 14:00:00"]})
first_date = my_df["my_column"].iloc[0]
print (first_date, type(first_date)) # 2019-04-01 00:15:00 <class 'str'>

# Change every element in the column from string to datetime object.
my_df["my_column"] = [datetime.datetime.strptime(element, "%Y-%m-%d %H:%M:%S").replace(tzinfo=forced_UTC) for element in my_df["my_column"]]
first_date = my_df["my_column"].iloc[0]
print (first_date, type(first_date)) # <class 'pandas._libs.tslibs.timestamps.Timestamp'>
# Didn't work, thought it would make them python datetime objects.

# Try creating a new list and replacing the column.
list_to_replace = [element.to_pydatetime() for element in my_df["my_column"]] # make all timestamps datetimes
print (list_to_replace[0],type(list_to_replace[0])) # 2019-04-01 01:15:00+01:00 <class 'datetime.datetime'>
my_df["my_column"] = [element for element in list_to_replace]
first_date = my_df["my_column"].iloc[0] 
print (first_date, type(first_date))# 2019-04-01 01:15:00+01:00 <class pandas._libs.tslibs.timestamps.Timestamp'>
# Didn't work.

# Use to_pydatetime() doesn't work either
print (first_date.to_pydatetime(), type(first_date)) # 2019-04-01 01:15:00+01:00 <class 'pandas._libs.tslibs.timestamps.Timestamp'>

# Using to_pydatetime() like this works!?!?!?!
first_date = my_df["my_column"].iloc[0].to_pydatetime()
print (first_date, type(first_date)) # 2019-04-01 01:15:00+01:00 <class 'datetime.datetime'>

# print (datetime.datetime.strftime(first_date, "%H"))
# print (datetime.datetime(2019, 4, 1, 0, 15, tzinfo=forced_BST) > first_date)

谁能看出我做错了什么？

Answer 1

它可以工作，但是您在打印 type 时没有修改类型。
在这里，您确实打印了一个熊猫日期 (first_date) 和一个熊猫类型 (type(first_date))。

first_date = my_df["my_column"].iloc[0] 
print (first_date, type(first_date)) # 2019-04-01 01:15:00+01:00 <class pandas._libs.tslibs.timestamps.Timestamp'>
# Didn't work.

在这种情况下，您打印的是 python 日期 (first_date.to_pydatetime())，因为您确实在使用 to_pydatetime，但从未修改 first_date 变量，因此type 还是熊猫约会。

print (first_date.to_pydatetime(), type(first_date)) # 2019-04-01 01:15:00+01:00 <class 'pandas._libs.tslibs.timestamps.Timestamp'>

并且在这里您还覆盖 first_date 带有 python 日期的变量，(first_date = first_date.to_pydatetime()) 这就是您考虑它的原因只有那时才工作。所以现在 first_date 将是 python 日期，因此 type(first_date) 将 return 你所期望的

# Using to_pydatetime() like this works!?!?!?!
first_date = my_df["my_column"].iloc[0].to_pydatetime()
print (first_date, type(first_date)) # 2019-04-01 01:15:00+01:00 <class 'datetime.datetime'>

如何将 pandas 时间戳更改为 python 日期时间对象？

How to change pandas timestamps to python datetime objects?

python

pandas

datetime

timestamp

pytz