Series.cumsum() is used to find the cumulative sum of a series. Cumulatively, the length of the returned series is the same as the input, and each item is the sum of all previous items.
Syntax: Series.cumsum (axis = None, skipna = True)
axis: 0 or ’index’ for row wise operation and 1 or ’columns’ for column wise operation
skipna: Skips NaN addition for elements after the very next one if True.
Result type: Series
Example # 1:
This example creates a series from a Python list using the Pandas .Series () method. The list also contains Null, and the skipna parameter remains the default, which is True.
3 7 NaN 14 16 16 dtype: float64
Accumulated amount — it is the sum of the current and all previous values. As shown in the output above, the addition was done as follows
3 3 + 4 = 7 7 + NaN = NaN 7 + 7 = 14 14 + 2 = 16 16 + 0 = 16
Example # 2: skipna = False
This example creates a series in the same way as the example above. But the
skipna parameter remains False. Therefore, NULL values will not be ignored and will be added each time it appears.
0 1.0 1 21.0 2 34.0 3 NaN 4 NaN 5 NaN 6 NaN 7 NaN dtype: float64
Explanation: As in As shown in the output, all values after the first occurrence of NaN are also NaN, since any number + NaN is also NaN.