pandas.Series.sort_values¶

Series.sort_values(axis=0, ascending=True, inplace=False, kind='quicksort', na_position='last', ignore_index=False, key=None)[source]

Sort by the values.

Sort a Series in ascending or descending order by some criterion.

Parameters
axis{0 or ‘index’}, default 0

Axis to direct sorting. The value ‘index’ is accepted for compatibility with DataFrame.sort_values.

ascendingbool, default True

If True, sort values in ascending order, otherwise descending.

inplacebool, default False

If True, perform operation in-place.

kind{‘quicksort’, ‘mergesort’ or ‘heapsort’}, default ‘quicksort’

Choice of sorting algorithm. See also numpy.sort() for more information. ‘mergesort’ is the only stable algorithm.

na_position{‘first’ or ‘last’}, default ‘last’

Argument ‘first’ puts NaNs at the beginning, ‘last’ puts NaNs at the end.

ignore_indexbool, default False

If True, the resulting axis will be labeled 0, 1, …, n - 1.

New in version 1.0.0.

keycallable, optional

If not None, apply the key function to the series values before sorting. This is similar to the key argument in the builtin sorted() function, with the notable difference that this key function should be vectorized. It should expect a Series and return an array-like.

New in version 1.1.0.

Returns
Series

Series ordered by values.

Series.sort_index

Sort by the Series indices.

DataFrame.sort_values

Sort DataFrame by the values along either axis.

DataFrame.sort_index

Sort DataFrame by indices.

Examples

>>> s = pd.Series([np.nan, 1, 3, 10, 5])
>>> s
0     NaN
1     1.0
2     3.0
3     10.0
4     5.0
dtype: float64


Sort values ascending order (default behaviour)

>>> s.sort_values(ascending=True)
1     1.0
2     3.0
4     5.0
3    10.0
0     NaN
dtype: float64


Sort values descending order

>>> s.sort_values(ascending=False)
3    10.0
4     5.0
2     3.0
1     1.0
0     NaN
dtype: float64


Sort values inplace

>>> s.sort_values(ascending=False, inplace=True)
>>> s
3    10.0
4     5.0
2     3.0
1     1.0
0     NaN
dtype: float64


Sort values putting NAs first

>>> s.sort_values(na_position='first')
0     NaN
1     1.0
2     3.0
4     5.0
3    10.0
dtype: float64


Sort a series of strings

>>> s = pd.Series(['z', 'b', 'd', 'a', 'c'])
>>> s
0    z
1    b
2    d
3    a
4    c
dtype: object

>>> s.sort_values()
3    a
1    b
4    c
2    d
0    z
dtype: object


Sort using a key function. Your key function will be given the Series of values and should return an array-like.

>>> s = pd.Series(['a', 'B', 'c', 'D', 'e'])
>>> s.sort_values()
1    B
3    D
0    a
2    c
4    e
dtype: object
>>> s.sort_values(key=lambda x: x.str.lower())
0    a
1    B
2    c
3    D
4    e
dtype: object


NumPy ufuncs work well here. For example, we can sort by the sin of the value

>>> s = pd.Series([-4, -2, 0, 2, 4])
>>> s.sort_values(key=np.sin)
1   -2
4    4
2    0
0   -4
3    2
dtype: int64


More complicated user-defined functions can be used, as long as they expect a Series and return an array-like

>>> s.sort_values(key=lambda x: (np.tan(x.cumsum())))
0   -4
3    2
4    4
1   -2
2    0
dtype: int64