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Version: Python

cum_min

cum_min calculates a cumulative minimum in an update_by table operation.

Syntax​

cum_min(cols: list[str]) -> UpdateByOperation

Parameters​

ParameterTypeDescription
colslist[str]

The column(s) to be operated on. These can include expressions to rename the output columns (e.g., NewCol = Col). If None, the cumulative minimum is calculated for all applicable columns in the table.

Returns​

An UpdateByOperation to be used in an update_by table operation.

Examples​

The following example performs an update_by on the source table using the cum_min operation. No grouping columns are given, so the cumulative minimum is calculated across all rows of the table.

from deephaven.updateby import cum_min
from deephaven import empty_table

source = empty_table(25).update(
    ["Letter = (i % 2 == 0) ? `A` : `B`", "X = randomInt(0, 25)"]
)

result = source.update_by(ops=cum_min(cols=["MinX = X"]), by=[])

The following example builds on the previous by specifying Letter as the grouping column. Thus, the cumulative minimum is calculated for each unique letter.

from deephaven.updateby import cum_min
from deephaven import empty_table

source = empty_table(25).update(
    ["Letter = (i % 2 == 0) ? `A` : `B`", "X = randomInt(0, 25)"]
)

result = source.update_by(ops=cum_min(cols=["MinX = X"]), by=["Letter"])

The following example builds on the previous by calculating the cumulative minimum of two different columns using the same UpdateByOperation.

from deephaven.updateby import cum_min
from deephaven import empty_table

source = empty_table(25).update(
    [
        "Letter = (i % 2 == 0) ? `A` : `B`",
        "X = randomInt(0, 25)",
        "Y = randomInt(10, 30)",
    ]
)

result = source.update_by(ops=cum_min(cols=["MinX = X", "MinY = Y"]), by=["Letter"])

The following example builds on the previous by grouping on two columns instead of one. Each group is defined by a unique combination of letter and boolean in the Letter and Truth columns, respectively.

from deephaven.updateby import cum_min
from deephaven import empty_table

source = empty_table(25).update(
    [
        "Letter = (i % 2 == 0) ? `A` : `B`",
        "Truth = randomBool()",
        "X = randomInt(0, 25)",
        "Y = randomInt(10, 30)",
    ]
)

result = source.update_by(
    ops=cum_min(cols=["MinX = X", "MinY = Y"]), by=["Letter", "Truth"]
)