参考自：http://stackoverflow.com/questions/35312981/using-pandas-to-datetime-with-timestamps
在pandas DataFrame中将timestamp转为datetime，关键要使用unit='s'。而不是ms、us或者其他选项。
0 1450753200.123213,
1 1450756800.123213,
2 1450760400.123213,
3 1450764000.123213,
4 1450767600.123213,
转换为datetime
In [106]:
pd.to_datetime(df['timestamp'], unit='s')
Out[106]:
index
0 2015-12-22 03:00:00
1 2015-12-22 04:00:00
2 2015-12-22 05:00:00
3 2015-12-22 06:00:00
4 2015-12-22 07:00:00
Name: timestamp, dtype: datetime64[ns]
转为字符串
In [107]:
pd.to_datetime(df['timestamp'], unit='s').dt.strftime('%Y-%m-%d %H:%M')
Out[107]:
index
0 2015-12-22 03:00
1 2015-12-22 04:00
2 2015-12-22 05:00
3 2015-12-22 06:00
4 2015-12-22 07:00
Name: timestamp, dtype: object