/usr/local/lib64/python3.6/site-packages/pandas/core
Edit: /usr/local/lib64/python3.6/site-packages/pandas/core/shared_docs.py (3551B)
from typing import Dict
_shared_docs: Dict[str, str] = dict()
_shared_docs[
"melt"
] = """
Unpivot a DataFrame from wide to long format, optionally leaving identifiers set.
This function is useful to massage a DataFrame into a format where one
or more columns are identifier variables (`id_vars`), while all other
columns, considered measured variables (`value_vars`), are "unpivoted" to
the row axis, leaving just two non-identifier columns, 'variable' and
'value'.
%(versionadded)s
Parameters
----------
id_vars : tuple, list, or ndarray, optional
Column(s) to use as identifier variables.
value_vars : tuple, list, or ndarray, optional
Column(s) to unpivot. If not specified, uses all columns that
are not set as `id_vars`.
var_name : scalar
Name to use for the 'variable' column. If None it uses
``frame.columns.name`` or 'variable'.
value_name : scalar, default 'value'
Name to use for the 'value' column.
col_level : int or str, optional
If columns are a MultiIndex then use this level to melt.
ignore_index : bool, default True
If True, original index is ignored. If False, the original index is retained.
Index labels will be repeated as necessary.
.. versionadded:: 1.1.0
Returns
-------
DataFrame
Unpivoted DataFrame.
See Also
--------
%(other)s : Identical method.
pivot_table : Create a spreadsheet-style pivot table as a DataFrame.
DataFrame.pivot : Return reshaped DataFrame organized
by given index / column values.
DataFrame.explode : Explode a DataFrame from list-like
columns to long format.
Examples
--------
>>> df = pd.DataFrame({'A': {0: 'a', 1: 'b', 2: 'c'},
... 'B': {0: 1, 1: 3, 2: 5},
... 'C': {0: 2, 1: 4, 2: 6}})
>>> df
A B C
0 a 1 2
1 b 3 4
2 c 5 6
>>> %(caller)sid_vars=['A'], value_vars=['B'])
A variable value
0 a B 1
1 b B 3
2 c B 5
>>> %(caller)sid_vars=['A'], value_vars=['B', 'C'])
A variable value
0 a B 1
1 b B 3
2 c B 5
3 a C 2
4 b C 4
5 c C 6
The names of 'variable' and 'value' columns can be customized:
>>> %(caller)sid_vars=['A'], value_vars=['B'],
... var_name='myVarname', value_name='myValname')
A myVarname myValname
0 a B 1
1 b B 3
2 c B 5
Original index values can be kept around:
>>> %(caller)sid_vars=['A'], value_vars=['B', 'C'], ignore_index=False)
A variable value
0 a B 1
1 b B 3
2 c B 5
0 a C 2
1 b C 4
2 c C 6
If you have multi-index columns:
>>> df.columns = [list('ABC'), list('DEF')]
>>> df
A B C
D E F
0 a 1 2
1 b 3 4
2 c 5 6
>>> %(caller)scol_level=0, id_vars=['A'], value_vars=['B'])
A variable value
0 a B 1
1 b B 3
2 c B 5
>>> %(caller)sid_vars=[('A', 'D')], value_vars=[('B', 'E')])
(A, D) variable_0 variable_1 value
0 a B E 1
1 b B E 3
2 c B E 5
"""