# Working with Lists

:::tip
Lists are equivalent to the individual columns of tables. You can think of a list as essentially being a "one-column table" (with no column name). Thus, any command which operates on a column _also_ operates on a list. For instance, [`where`](/commands/docs/where.md) can be used with lists:

```nu
[bell book candle] | where ($it =~ 'b')
# => ╭───┬──────╮
# => │ 0 │ bell │
# => │ 1 │ book │
# => ╰───┴──────╯
```

:::

## Creating lists

A list is an ordered collection of values.
A list is created using square brackets surrounding values separated by spaces, linebreaks, and/or commas.
For example, `[foo bar baz]` or `[foo, bar, baz]`.

::: tip
Nushell lists are similar to JSON arrays. The same `[ "Item1", "Item2", "Item3" ]` that represents a JSON array can also be used to create a Nushell list.
:::

## Updating lists

We can [`insert`](/commands/docs/insert.md) values into lists as they flow through the pipeline, for example let's insert the value `10` into the middle of a list:

```nu
[1, 2, 3, 4] | insert 2 10
# => [1, 2, 10, 3, 4]
```

We can also use [`update`](/commands/docs/update.md) to replace the 2nd element with the value `10`.

```nu
[1, 2, 3, 4] | update 1 10
# => [1, 10, 3, 4]
```

## Removing or Adding Items from List

In addition to [`insert`](/commands/docs/insert.md) and [`update`](/commands/docs/update.md), we also have [`prepend`](/commands/docs/prepend.md) and [`append`](/commands/docs/append.md). These let you insert to the beginning of a list or at the end of the list, respectively.

For example:

```nu
let colors = [yellow green]
let colors = ($colors | prepend red)
let colors = ($colors | append purple)
let colors = ($colors ++ ["blue"])
let colors = (["black"] ++ $colors)
$colors
# => [black red yellow green purple blue]
```

In case you want to remove items from list, there are many ways. [`skip`](/commands/docs/skip.md) allows you skip first rows from input, while [`drop`](/commands/docs/drop.md) allows you to skip specific numbered rows from end of list.

```nu
let colors = [red yellow green purple]
let colors = ($colors | skip 1)
let colors = ($colors | drop 2)
$colors
# => [yellow]
```

We also have [`last`](/commands/docs/last.md) and [`first`](/commands/docs/first.md) which allow you to [`take`](/commands/docs/take.md) from the end or beginning of the list, respectively.

```nu
let colors = [red yellow green purple black magenta]
let colors = ($colors | last 3)
$colors
# => [purple black magenta]
```

And from the beginning of a list,

```nu
let colors = [yellow green purple]
let colors = ($colors | first 2)
$colors
# => [yellow green]
```

### Using the Spread Operator

To append one or more lists together, optionally with values interspersed in between, you can also use the
[spread operator](/book/operators#spread-operator) (`...`):

```nu
let x = [1 2]
[
  ...$x
  3
  ...(4..7 | take 2)
]
# => ╭───┬───╮
# => │ 0 │ 1 │
# => │ 1 │ 2 │
# => │ 2 │ 3 │
# => │ 3 │ 4 │
# => │ 4 │ 5 │
# => ╰───┴───╯
```

## Iterating over Lists

To iterate over the items in a list, use the [`each`](/commands/docs/each.md) command with a [block](types_of_data.html#blocks)
of Nu code that specifies what to do to each item. The block parameter (e.g. `|elt|` in `{ |elt| print $elt }`) is the current list
item, but the [`enumerate`](/commands/docs/enumerate.md) filter can be used to provide `index` and `item` values if needed. For example:

```nu
let names = [Mark Tami Amanda Jeremy]
$names | each { |elt| $"Hello, ($elt)!" }
# Outputs "Hello, Mark!" and three more similar lines.

$names | enumerate | each { |elt| $"($elt.index + 1) - ($elt.item)" }
# Outputs "1 - Mark", "2 - Tami", etc.
```

The [`where`](/commands/docs/where.md) command can be used to create a subset of a list, effectively filtering the list based on a condition.

The following example gets all the colors whose names end in "e".

```nu
let colors = [red orange yellow green blue purple]
$colors | where ($it | str ends-with 'e')