# What is the Cumulative Sum of a pandas DataFrame?

In many DataFrame operations, the result is based on the value of the current row/observation. Yet, there are many applications where the cumulative value of all rows is essential for analysis.

Below is a dataset of daily confirmed cases of COVID-19:

## Finding the Cumulative Sum

The cumulative sum is calculated by pandas using the `cumsum`

function on the column of a DataFrame. For example, if we want to find the Total Confirmed cases so far this year:

`df["Total Confirmed"] = df["Confirmed"].cumsum()`

Date | Confirmed | Total Confirmed | |
---|---|---|---|

0 | 2022-01-01 | 7 | 7 |

1 | 2022-01-02 | 4 | 11 |

2 | 2022-01-03 | 12 | 23 |

3 | 2022-01-04 | 9 | 32 |

4 | 2022-01-05 | 10 | 42 |

`cumsum`

function to create a cumulative sum.Notice that the new column, `Total Confirmed`

, contains the sum of all the confirmed cases up to, and including, the current row!

## Pandas Documentation

Click Here for the full pandas documentation for the `cumsum`

function