Convert epoch time to formatted date string in pandas dataframe

Question

I have a DataFrame with epoch timestamp and I want to create a new column with a formatted date string.

index   timestamp
0       1456407930
1       1456407945
2       1456407961
3       1456407977
4       1456407992
5       1456408008
6       1456408024
7       1456408040
8       1456408055
9       1456408071
10      1456408087
11      1456408102

First, I successfully convert the timestamp to datetime format using

data['date_num'] = mdate.epoch2num(data['timestamp'])

But I didn't find a function to get a new column with a string formatted date (such as “%Y-%m-%d”).

I would appreciate any ideas? Patricio

Answer 1

Specify unit='s' with pd.to_datetime. Then use pd.Series.dt.strftime.

df['date'] = pd.to_datetime(df['timestamp'], unit='s')\
               .dt.strftime('%Y-%m-%d')

print(df)

    index   timestamp        date
0       0  1456407930  2016-02-25
1       1  1456407945  2016-02-25
2       2  1456407961  2016-02-25
3       3  1456407977  2016-02-25
4       4  1456407992  2016-02-25
5       5  1456408008  2016-02-25
6       6  1456408024  2016-02-25
7       7  1456408040  2016-02-25
8       8  1456408055  2016-02-25
9       9  1456408071  2016-02-25
10     10  1456408087  2016-02-25
11     11  1456408102  2016-02-25

Answer 2

You can use map method by passing a lambda expression as argument.

df['new_column'] = df['timestamp'].map(lambda val: datetime.datetime.fromtimestamp(val).strftime('%Y-%m-%d'))

Output

    timestamp  new_column
0  1456407930  2016-02-25
1  1456407945  2016-02-25
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