Question

为什么这个“pythonic”代码不适用于tz_localize()行？

import pandas as pd

df = pd.DataFrame([{ "Localtime":"2016-01-01 12:00:00", "Timezone":"Europe/London" }, 
                   { "Localtime":"2016-01-01 12:00:00", "Timezone":"Europe/Paris" }])

df['UtcDateTime'] = pd.to_datetime(df['Localtime']).tz_localize(df['Timezone'])
df

我正在寻找一些比以下代码更漂亮的代码（工作正常btw）：

import pandas as pd

df = pd.DataFrame([{ "Localtime":"2016-01-01 12:00:00", "Timezone":"Europe/London" },
                   { "Localtime":"2016-01-01 12:00:00", "Timezone":"Europe/Paris" }])

df['UtcDateTime'] = 'NA'
i=0
for ts in df.Localtime:
    ts1 = pd.to_datetime(ts).tz_localize(df.Timezone[i])
    df['UtcDateTime'][i] = ts1
    i=i+1
df

预期结果：

    Localtime           Timezone        UtcDateTime
0   2016-01-01 12:00:00 Europe/London   2016-01-01 12:00:00+00:00
1   2016-01-01 12:00:00 Europe/Paris    2016-01-01 12:00:00+01:00

Answer 1

您可能只想选择apply

df.apply(lambda x: pd.to_datetime(x.Localtime).tz_localize(x.Timezone), axis=1)

<强>演示

>>> df['UtcDateTime'] = df.apply(lambda x:  pd.to_datetime(x.Localtime).tz_localize(x.Timezone), axis=1)

>>> df
             Localtime       Timezone                UtcDateTime
0  2016-01-01 12:00:00  Europe/London  2016-01-01 12:00:00+00:00
1  2016-01-01 12:00:00   Europe/Paris  2016-01-01 12:00:00+01:00

您的简短方法不起作用的原因是tz_localize确实需要索引来处理，而不是值。我建议你将它转换为类似pd.DatetimeIndex的DatetimeIndex，然而，tz_localize只接受一个时区，因此无论如何你最终会申请过行。

Answer 2

您的代码无效，因为tz_localize()期望将单个时区应用于系列中的多个值。为了使你的循环更清洁，你可以使用apply()：

<强>代码：

def localize_ts(row):
    return pd.to_datetime(row['Localtime']).tz_localize(row['Timezone'])

df['UtcDateTime'] = df.apply(localize_ts, axis=1)

<强>产地：

             Localtime       Timezone                UtcDateTime
0  2016-01-01 12:00:00  Europe/London  2016-01-01 12:00:00+00:00
1  2016-01-01 12:00:00   Europe/Paris  2016-01-01 12:00:00+01:00

如何正确设置pandas tz_localize？

2 个答案: