DataFrame.
set_index
Set the DataFrame index (row labels) using one or more existing columns.
Set the DataFrame index (row labels) using one or more existing columns or arrays (of the correct length). The index can replace the existing index or expand on it.
This parameter can be either a single column key, a single array of the same length as the calling DataFrame, or a list containing an arbitrary combination of column keys and arrays. Here, “array” encompasses Series, Index and np.ndarray.
Series
Index
np.ndarray
Delete columns to be used as the new index.
Whether to append columns to existing index.
Modify the DataFrame in place (do not create a new object).
Changed row labels.
See also
DataFrame.reset_index
Opposite of set_index.
Examples
>>> df = ps.DataFrame({'month': [1, 4, 7, 10], ... 'year': [2012, 2014, 2013, 2014], ... 'sale': [55, 40, 84, 31]}, ... columns=['month', 'year', 'sale']) >>> df month year sale 0 1 2012 55 1 4 2014 40 2 7 2013 84 3 10 2014 31
Set the index to become the ‘month’ column:
>>> df.set_index('month') year sale month 1 2012 55 4 2014 40 7 2013 84 10 2014 31
Create a MultiIndex using columns ‘year’ and ‘month’:
>>> df.set_index(['year', 'month']) sale year month 2012 1 55 2014 4 40 2013 7 84 2014 10 31