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Indicate if this expression only selects columns (optionally with aliasing)

Description

This can include bare columns, column matches by regex or dtype, selectors and exclude ops, and (optionally) column/expression aliasing.

Usage

<Expr>$meta$is_column_selection(..., allow_aliasing = FALSE)

Arguments

… These dots are for future extensions and must be empty.
allow_aliasing If FALSE (default), any aliasing is not considered pure column selection. Set TRUE to allow for column selection that also includes aliasing.

Value

A logical value.

Examples

library("polars")

e <- pl$col("foo")
e$meta$is_column_selection()

#> [1] TRUE

e <- pl$col("foo")$alias("bar")
e$meta$is_column_selection()

#> [1] FALSE

e$meta$is_column_selection(allow_aliasing = TRUE)

#> [1] TRUE

e <- pl$col("foo") * pl$col("bar")
e$meta$is_column_selection()

#> [1] FALSE

e <- cs$starts_with("foo")
e$meta$is_column_selection()

#> [1] TRUE