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Apply filter to LazyFrame

Source code

Description

Filter rows with an Expression defining a boolean column. Multiple expressions are combined with & (AND). This is equivalent to dplyr::filter().

Usage

<LazyFrame>$filter(...)

Arguments

… Polars expressions which will evaluate to a boolean.

Details

Rows where the condition returns NA are dropped.

Value

A new LazyFrame object with add/modified column.

Examples

library("polars")

lf = as_polars_lf(iris)

lf$filter(pl$col("Species") == "setosa")$collect()

#> shape: (50, 5)
#> ┌──────────────┬─────────────┬──────────────┬─────────────┬─────────┐
#> │ Sepal.Length ┆ Sepal.Width ┆ Petal.Length ┆ Petal.Width ┆ Species │
#> │ ---          ┆ ---         ┆ ---          ┆ ---         ┆ ---     │
#> │ f64          ┆ f64         ┆ f64          ┆ f64         ┆ cat     │
#> ╞══════════════╪═════════════╪══════════════╪═════════════╪═════════╡
#> │ 5.1          ┆ 3.5         ┆ 1.4          ┆ 0.2         ┆ setosa  │
#> │ 4.9          ┆ 3.0         ┆ 1.4          ┆ 0.2         ┆ setosa  │
#> │ 4.7          ┆ 3.2         ┆ 1.3          ┆ 0.2         ┆ setosa  │
#> │ 4.6          ┆ 3.1         ┆ 1.5          ┆ 0.2         ┆ setosa  │
#> │ 5.0          ┆ 3.6         ┆ 1.4          ┆ 0.2         ┆ setosa  │
#> │ …            ┆ …           ┆ …            ┆ …           ┆ …       │
#> │ 4.8          ┆ 3.0         ┆ 1.4          ┆ 0.3         ┆ setosa  │
#> │ 5.1          ┆ 3.8         ┆ 1.6          ┆ 0.2         ┆ setosa  │
#> │ 4.6          ┆ 3.2         ┆ 1.4          ┆ 0.2         ┆ setosa  │
#> │ 5.3          ┆ 3.7         ┆ 1.5          ┆ 0.2         ┆ setosa  │
#> │ 5.0          ┆ 3.3         ┆ 1.4          ┆ 0.2         ┆ setosa  │
#> └──────────────┴─────────────┴──────────────┴─────────────┴─────────┘

# This is equivalent to
# lf$filter(pl$col("Sepal.Length") > 5 & pl$col("Petal.Width") < 1)
lf$filter(pl$col("Sepal.Length") > 5, pl$col("Petal.Width") < 1)

#> polars LazyFrame
#>  $explain(): Show the optimized query plan.
#> 
#> Naive plan:
#> FILTER [(col("Sepal.Length")) > (5.0)] FROM
#>   FILTER [(col("Petal.Width")) < (1.0)] FROM
#>     DF ["Sepal.Length", "Sepal.Width", "Petal.Length", "Petal.Width"]; PROJECT */5 COLUMNS; SELECTION: None