Materialize this LazyFrame into a DataFrame

Source code

Description

By default, all query optimizations are enabled. Individual optimizations may be disabled by setting the corresponding parameter to FALSE.

Usage

<LazyFrame>$collect(
  ...,
  engine = c("auto", "in-memory", "streaming"),
  optimizations = pl\$QueryOptFlags()
)

Arguments

…	These dots are for future extensions and must be empty.
engine	The engine name to use for processing the query. One of the followings: “auto” (default): Select the engine automatically. In Polars 1.16, the “in-memory” engine is selected for most cases. Starting with Polars 2.0, the streaming engine is selected instead. Use “in-memory” to keep the current execution engine explicitly. “in-memory”: Use the in-memory engine. This is an escape hatch for queries whose incidental row order differs under streaming. “streaming”: Use the streaming engine.
optimizations	A QueryOptFlags object to indicate optimization passes done during query optimization.

Value

A polars DataFrame

See Also

• $sink_parquet() streams query to a parquet file.
• $sink_ipc() streams query to a arrow file.

Examples

library("polars")

lf <- pl$LazyFrame(
  a = c("a", "b", "a", "b", "b", "c"),
  b = 1:6,
  c = 6:1,
)
lf$group_by("a")$agg(pl$all()$sum())$collect()

#> shape: (3, 3)
#> ┌─────┬─────┬─────┐
#> │ a   ┆ b   ┆ c   │
#> │ --- ┆ --- ┆ --- │
#> │ str ┆ i32 ┆ i32 │
#> ╞═════╪═════╪═════╡
#> │ a   ┆ 4   ┆ 10  │
#> │ b   ┆ 11  ┆ 10  │
#> │ c   ┆ 6   ┆ 1   │
#> └─────┴─────┴─────┘

# Collect in streaming mode
lf$group_by("a")$agg(pl$all()$sum())$collect(
  engine = "streaming"
)

#> shape: (3, 3)
#> ┌─────┬─────┬─────┐
#> │ a   ┆ b   ┆ c   │
#> │ --- ┆ --- ┆ --- │
#> │ str ┆ i32 ┆ i32 │
#> ╞═════╪═════╪═════╡
#> │ a   ┆ 4   ┆ 10  │
#> │ b   ┆ 11  ┆ 10  │
#> │ c   ┆ 6   ┆ 1   │
#> └─────┴─────┴─────┘