R: Flatten a list of lists into a simple vector.

flatten {purrr} | R Documentation

## Flatten a list of lists into a simple vector.

### Description

These functions remove a level hierarchy from a list. They are similar to `unlist`, only ever remove a single layer of hierarchy, and are type-stable so you always know what the type of the output is.

### Usage

    flatten(.x)

    flatten_lgl(.x)

    flatten_int(.x)

    flatten_dbl(.x)

    flatten_chr(.x)

    flatten_df(.x, .id = NULL)

### Arguments

`.x` | A list of flatten. The contents of the list can be anything for `flatten` (as a list is returned), but the contents must match the type for the other functions.
`.id` | If not `NULL` a variable with this name will be created giving either the name or the index of the data frame.

### Value

`flatten()` returns a list, `flatten_lgl` a logical vector, `flatten_int` an integer vector, `flatten_dbl` a double vector, and `flatten_chr` a character vector.

### Examples

    x <- rerun(2, sample(4))
    x
    x %>% flatten()
    x %>% flatten_int()

    # You can use flatten in conjunction with map
    x %>% map(1L) %>% flatten_int()
    # But it's more efficient to use the typed map instead.
    x %>% map_int(1L)

[Package purrr version 0.2.2 Index]