def diff(self, periods=<NUM_LIT:1>):
result = algorithms.diff(com.values_from_object(self), periods)<EOL>return self._constructor(result, index=self.index).__finalize__(self)<EOL>
First discrete difference of element.

Calculates the difference of a Series element compared with another
element in the Series (default is element in previous row).

Parameters
----------
periods : int, default 1
    Periods to shift for calculating difference, accepts negative
    values.

Returns
-------
Series
    First differences of the Series.

See Also
--------
Series.pct_change: Percent change over given number of periods.
Series.shift: Shift index by desired number of periods with an
    optional time freq.
DataFrame.diff: First discrete difference of object.

Examples
--------
Difference with previous row

>>> s = pd.Series([1, 1, 2, 3, 5, 8])
>>> s.diff()
0    NaN
1    0.0
2    1.0
3    1.0
4    2.0
5    3.0
dtype: float64

Difference with 3rd previous row

>>> s.diff(periods=3)
0    NaN
1    NaN
2    NaN
3    2.0
4    4.0
5    6.0
dtype: float64

Difference with following row

>>> s.diff(periods=-1)
0    0.0
1   -1.0
2   -1.0
3   -2.0
4   -3.0
5    NaN
dtype: float64