Subset rows using their positions

This is a method for the dplyr::slice_head() generic. slice_head() selects the first rows.

# S3 method for class 'duckplyr_df'
slice_head(.data, ..., n, prop, by = NULL)

Arguments

.data

A data frame, data frame extension (e.g. a tibble), or a lazy data frame (e.g. from dbplyr or dtplyr). See Methods, below, for more details.

...

For slice(): <data-masking> Integer row values.

Provide either positive values to keep, or negative values to drop. The values provided must be either all positive or all negative. Indices beyond the number of rows in the input are silently ignored.

For slice_*(), these arguments are passed on to methods.

n, prop

Provide either n, the number of rows, or prop, the proportion of rows to select. If neither are supplied, n = 1 will be used. If n is greater than the number of rows in the group (or prop > 1), the result will be silently truncated to the group size. prop will be rounded towards zero to generate an integer number of rows.

A negative value of n or prop will be subtracted from the group size. For example, n = -2 with a group of 5 rows will select 5 - 2 = 3 rows; prop = -0.25 with 8 rows will select 8 * (1 - 0.25) = 6 rows.

by

<tidy-select> Optionally, a selection of columns to group by for just this operation, functioning as an alternative to group_by(). For details and examples, see ?dplyr_by.

Fallbacks

There is no DuckDB translation in slice_head.duckplyr_df()

• if by or prop is provided,

• with a negative n.

These features fall back to dplyr::slice_head(), see vignette("fallback") for details.

See also

dplyr::slice_head()

Examples

library(duckplyr)
df <- data.frame(x = 1:3)
df <- slice_head(df, n = 2)
df
#>   x
#> 1 1
#> 2 2