CumMax
CumMax calculates the cumulative maximum in an updateBy table operation.
Syntax
CumMax(pairs...)
Parameters
| Parameter | Type | Description |
|---|---|---|
| pairs | String... | The column(s) to be operated on. These can include expressions to rename the output columns (e.g., |
Returns
An UpdateByOperation to be used in an updateBy table operation.
Examples
The following example performs an updateBy on the source table using the CumMax operation. No grouping columns are given. As a result, the cumulative maximum is calculated for all rows.
source = emptyTable(25).update("Letter = (i % 2 == 0) ? `A` : `B`", "X = randomInt(0, 25)")
result = source.updateBy(CumMax("MaxX = X"))
- source
- result
The following example builds on the previous example by specifying Letter as the grouping column. Thus, the result table has cumulative maximum calculated per unique letter in that column.
source = emptyTable(25).update("Letter = (i % 2 == 0) ? `A` : `B`", "X = randomInt(0, 25)")
result = source.updateBy(CumMax("MaxX = X"), "Letter")
- source
- result
The following example builds on the previous example by calculating the cumulative maximum for two columns using a single UpdateByOperation.
source = emptyTable(25).update("Letter = (i % 2 == 0) ? `A` : `B`", "X = randomInt(0, 25)", "Y = randomInt(25, 50)")
result = source.updateBy(CumMax("MaxX = X", "MaxY = Y"), "Letter")
- source
- result
The following example builds on the previous example by specifying two key columns. Thus, each group is a unique combination of letter in the Letter column and boolean in the Truth column.
source = emptyTable(25).update("Letter = (i % 2 == 0) ? `A` : `B`", "Truth = randomBool()", "X = randomInt(0, 25)", "Y = randomInt(25, 50)")
result = source.updateBy(CumMax("MaxX = X", "MaxY = Y"), "Letter", "Truth")
- source
- result