df-research/dataframe/docs/StardustDocs/topics/cumSum.md

Computes the cumulative sum of values in the selected columns.

cumSum(skipNA = true) [ { columns } ]

Returns a DataFrame or DataColumn containing the cumulative sum.

See column selectors for how to select the columns for this operation.

Parameters:

• skipNA — when true, ignores NA values (null or NaN). When false, all values after first NA will be NaN (for Double and Float columns) or null (for integer columns).

Available for:

• DataFrame
• DataColumn
• GroupBy DataFrame — cumulative sum per every data group

df.cumSum { weight }
df.weight.cumSum()
df.groupBy { city }.cumSum { weight }.concat()