Too many values to unpack (expected 3) error when splitting a column

Question

Too many values to unpack (expected 3) error when splitting a column

When using the split method for DataFrame Views, an error occurs: too many values to unpack (expected 3). The task is to split the Date column into 3 columns year, month, day, and then translate it into a date. What am I doing wrong, please tell me? Code:

year, month, day = views.Date.str.split('/')

1

python pandas дата

Author: Denis Novik, 2017-01-25

Source

1 answers

score 2 · Accepted Answer

Answering your question about .str.split(...):

In .str.split(..., expand=False) by default expand=False, i.e. it will return pandas.Series where the elements will be lists:

In [49]: df.date.str.split('/')
Out[49]:
0    [2016, 01, 09]
1    [2016, 11, 11]
2    [2016, 12, 30]
Name: date, dtype: object

If you specify expand=True, it returns pandas.DataFrame:

In [50]: df.date.str.split('/', expand=True)
Out[50]:
      0   1   2
0  2016  01  09
1  2016  11  11
2  2016  12  30

You can also use .str.extract() and specify the column names:

In [51]: df.date.str.extract(r'(?P<year>\d{4})[-/\.](?P<month>\d{2})[-/\.](?P<day>\d{2})', expand=True)
Out[51]:
   year month day
0  2016    01  09
1  2016    11  11
2  2016    12  30

In [52]: split = df.date.str.extract(r'(?P<year>\d{4})[-/\.](?P<month>\d{2})[-/\.](?P<day>\d{2})', expand=True)

In [53]: split
Out[53]:
   year month day
0  2016    01  09
1  2016    11  11
2  2016    12  30