partitionedTransform

The partitionedTransform method applies the supplied transformer to all constituent tables found in this (the PartitionedTable instance that calls partitionedTransform) and other (the other partitioned table that will be merged/joined with this) with the same key column values. It produces a new PartitionedTable containing the results.

other's key columns must match this PartitionedTable's key columns. Two matching mechanisms are supported, and will be attempted in the order listed:

• Match by column name. Both PartitionedTables must have all the same key column names. Like-named columns must have the same data type and component type.
• Match by column order. Both PartitionedTables must have their matchable columns in the same order within their key column names. Like-positioned columns must have the same data type and component type.
• This overload uses the enclosing ExecutionContext and expects the transformer to produce refreshing results if and only if this or other has a refreshing underlying table.

Syntax

partitionedTransform(other, transformer, dependencies...)
partitionedTransform(other, executionContext, transformer, expectRefreshingResults, dependencies...)

Parameters

Parameter	Type	Description
other	PartitionedTable	The other PartitionedTable to find constituents in.
transformer	BinaryOperator<Table>	The BinaryOperator to apply to all pairs of constituent tables.
dependencies	NotificationQueue.Dependency...	Additional dependencies that must be satisfied before applying transformer to added, modified, or newly-matched constituents during update processing; use this when transformer uses additional Table or PartitionedTable inputs besides the constituents of this or other.
executionContext	ExecutionContext	The ExecutionContext to use for the transformer.
expectRefreshingResults	boolean	Whether to expect the results of applying transformer to be refreshing. If true, the resulting PartitionedTable will always be backed by a refreshing table. This hint is important for transforms to static inputs that might produce refreshing output, in order to ensure correct liveness management; incorrectly specifying false will result in exceptions.

Returns

A new PartitionedTable containing the results of applying transformer to all pairs of constituent tables found in this and other with the same key column values.

Examples

In the following example, two tables are created and partitioned by the X column. The partitionedTransform method is used to apply a transformer that returns the first table in the partitioned table. The result is a new partitioned table that is coalesced into a single table with merge.

import io.deephaven.engine.context.ExecutionContext
import io.deephaven.util.SafeCloseable

t1 = emptyTable(10).update('X = i % 2', 'Y = randomDouble(0.0, 100.0)')
t2 = emptyTable(10).update('X = i % 2', 'Z = randomDouble(100.0, 500.0)')

pt1 = t1.partitionBy('X')
pt2 = t2.partitionBy('X')

defaultCtx = ExecutionContext.getContext()

transformer = { t1, t2 ->
    try (SafeCloseable ignored = defaultCtx.open()) {
        return t1
    }
}

pt3 = pt1.partitionedTransform(pt2, transformer)

result = pt3.merge()

result

t1

t2

In this example, the transformer returns the result of joining the two tables on the "X" column. The result is a new partitioned table that is then coalesced into a single table with merge.

import io.deephaven.engine.context.ExecutionContext
import io.deephaven.util.SafeCloseable

t1 = emptyTable(10).update('X = i % 2', 'Y = randomDouble(0.0, 100.0)')
t2 = emptyTable(10).update('X = i % 2', 'Z = randomDouble(100.0, 500.0)')

pt1 = t1.partitionBy('X')
pt2 = t2.partitionBy('X')

defaultCtx = ExecutionContext.getContext()

transformer = { t1, t2 ->
    try (SafeCloseable ignored = defaultCtx.open()) {
        return t1.join(t2, 'X')
    }
}

pt3 = pt1.partitionedTransform(pt2, transformer)

result = pt3.merge()

result

t1

t2

In this example, the transformer returns the result of an aj between two tables. The result is a new partitioned table that is then coalesced into a single table with merge.

import io.deephaven.engine.context.ExecutionContext
import io.deephaven.util.SafeCloseable

trades = newTable(
    stringCol('Ticker', 'AAPL', 'AAPL', 'AAPL', 'IBM', 'IBM'),
    instantCol('Timestamp',
        parseInstant('2021-04-05T09:10:00 ET'), parseInstant('2021-04-05T09:31:00 ET'),
        parseInstant('2021-04-05T16:00:00 ET'), parseInstant('2021-04-05T16:00:00 ET'),
        parseInstant('2021-04-05T16:30:00 ET')),
    doubleCol('Price', 2.5, 3.7, 3.0, 100.50, 110),
    intCol('Size', 52, 14, 73, 11, 6)
)

quotes = newTable(
    stringCol('Ticker', 'AAPL', 'AAPL', 'IBM', 'IBM', 'IBM'),
    instantCol('Timestamp',
        parseInstant('2021-04-05T09:11:00 ET'), parseInstant('2021-04-05T09:30:00 ET'),
        parseInstant('2021-04-05T16:00:00 ET'), parseInstant('2021-04-05T16:30:00 ET'),
        parseInstant('2021-04-05T17:00:00 ET')),
    doubleCol('Bid', 2.5, 3.4, 97, 102, 108),
    intCol('BidSize', 10, 20, 5, 13, 23),
    doubleCol('Ask', 2.5, 3.4, 105, 110, 111),
    intCol('AskSize', 83, 33, 47, 15, 5)
)

ptTrades = trades.partitionBy('Ticker')
ptQuotes = quotes.partitionBy('Ticker')

defaultCtx = ExecutionContext.getContext()

ptAsOfJoin = { quotes, trades ->
    try (SafeCloseable ignored = defaultCtx.open()) {
        return trades.aj(quotes, 'Ticker, Timestamp')
    }
}

pt3 = ptTrades.partitionedTransform(ptQuotes, ptAsOfJoin)

result = pt3.merge()

result

trades

quotes

Related documentation

• Javadoc