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Version: Python

where_in

The where_in method returns a new table containing rows from the source table, where the rows match values in the filter table. The filter is updated whenever either table changes.

note

where_in is not appropriate for all situations. Its purpose is to enable more efficient filtering for an infrequently changing filter table.

Syntax​

table.where_in(filter_table: Table, cols: Union[str, list[str]]) -> Table

Parameters​

ParameterTypeDescription
filter_tableTable

The table containing the set of values to filter on.

colsUnion[str, list[str]]

A list of columns (as Strings) to match between the two tables.

  • "X" will match on the same column name. Equivalent to "X = X".
  • "X = Y" will match when the columns have different names, with X being the source table column and Y being the filter table column.

Returns​

A new table containing rows from the source table, where the rows match values in the filter table. The filter is updated whenever either table changes.

Examples​

The following example creates a table containing only the colors present in the filter table.

from deephaven import new_table
from deephaven.column import string_col, int_col, double_col
from deephaven.constants import NULL_INT

source = new_table(
    [
        string_col("Letter", ["A", "C", "F", "B", "E", "D", "A"]),
        int_col("Number", [NULL_INT, 2, 1, NULL_INT, 4, 5, 3]),
        string_col(
            "Color", ["red", "blue", "orange", "purple", "yellow", "pink", "blue"]
        ),
        int_col("Code", [12, 14, 11, NULL_INT, 16, 14, NULL_INT]),
    ]
)


filter = new_table([string_col("Colors", ["blue", "red", "purple", "white"])])

result = source.where_in(filter_table=filter, cols=["Color = Colors"])

The following example creates a table containing only the colors and codes not present in the filter table. When using multiple matches, the resulting table will exclude only values that are not in both matches. In this example, only one row matches both color AND codes. This results in a new table that has all but one matching value.

from deephaven import new_table
from deephaven.column import string_col, int_col, double_col
from deephaven.constants import NULL_INT

source = new_table(
    [
        string_col("Letter", ["A", "C", "F", "B", "E", "D", "A"]),
        int_col("Number", [NULL_INT, 2, 1, NULL_INT, 4, 5, 3]),
        string_col(
            "Color", ["red", "blue", "orange", "purple", "yellow", "pink", "blue"]
        ),
        int_col("Code", [12, 13, 11, 10, 16, 14, NULL_INT]),
    ]
)
filter = new_table(
    [
        string_col("Colors", ["blue", "red", "purple", "white"]),
        int_col("Codes", [10, 12, 14, 16]),
    ]
)

result = source.where_in(filter_table=filter, cols=["Color = Colors", "Code = Codes"])