数据框列中的日期转换为MM / DD / YYYY

Question

I have 4 dataframes named df1 , df2 , df3 , df4 with one column Date . The column consist of dates with different format. df1 has date column of type int64, df2 has date column of type object, df3 has date column has type object, df4 has date column of type object. Below are the dataframe and its data.

df1:
          Date
0     20160301
1     20160301
2     20160301
3     20160301

df2: 
      Date
0   01/03/2016
1   01/03/2016
2   01/03/2016

df3:
      Date
0   31-Mar-16
1   31-Mar-16
2   31-Mar-16

df4:
      Date
0  25/02/2016
1  25/02/2016
2  25/02/2016

I want to convert these dates in the form as mm/dd/yyyy of type date . Can anyone help me on this?

Answer 1

I think you can use to_datetime and dt.strftime , but type is not datetime , but string :

df1['Date'] = pd.to_datetime(df1['Date'], format='%Y%m%d').dt.strftime('%m/%d/%Y')
df2['Date'] = pd.to_datetime(df2['Date']).dt.strftime('%m/%d/%Y')
df3['Date'] = pd.to_datetime(df3['Date']).dt.strftime('%m/%d/%Y')
df4['Date'] = pd.to_datetime(df4['Date']).dt.strftime('%m/%d/%Y')

print df1
print df2
print df3
print df4
         Date
0  03/01/2016
1  03/01/2016
2  03/01/2016
3  03/01/2016
         Date
0  01/03/2016
1  01/03/2016
2  01/03/2016
         Date
0  03/31/2016
1  03/31/2016
2  03/31/2016
         Date
0  02/25/2016
1  02/25/2016
2  02/25/2016

print type(df1.at[0,'Date'])
<type 'str'>

If you want datetime , format is YY-MM-DD :

df1['Date'] = pd.to_datetime(df1['Date'], format='%Y%m%d')
df2['Date'] = pd.to_datetime(df2['Date'])
df3['Date'] = pd.to_datetime(df3['Date'])
df4['Date'] = pd.to_datetime(df4['Date'])

print df1
print df2
print df3
print df4
        Date
0 2016-03-01
1 2016-03-01
2 2016-03-01
3 2016-03-01
        Date
0 2016-01-03
1 2016-01-03
2 2016-01-03
        Date
0 2016-03-31
1 2016-03-31
2 2016-03-31
        Date
0 2016-02-25
1 2016-02-25
2 2016-02-25

print type(df1.at[0,'Date'])
<class 'pandas.tslib.Timestamp'>

More info about formating datetime is here .