> For the complete documentation index, see [llms.txt](https://motivlabs.gitbook.io/impulse-user-manual/llms.txt). Markdown versions of documentation pages are available by appending `.md` to page URLs; this page is available as [Markdown](https://motivlabs.gitbook.io/impulse-user-manual/content-manipulators-motators/liquid-field/filters/compact.md).

# compact

Removes any `nil` values from an array.

For this example, assume `site.pages` is an array of content pages for a website, and some of these pages have an attribute called `category` that specifies their content category. If we `map` those categories to an array, some of the array items might be `nil` if any pages do not have a `category` attribute.

Input

```
{% assign site_categories = site.pages | map: "category" %}

{% for category in site_categories %}
- {{ category }}
{% endfor %}
```

Output

```
- business
- celebrities
-
- lifestyle
- sports
-
- technology
```

By using `compact` when we create our `site_categories` array, we can remove all the `nil` values in the array.

Input

```
{% assign site_categories = site.pages | map: "category" | compact %}

{% for category in site_categories %}
- {{ category }}
{% endfor %}
```

Output

```
- business
- celebrities
- lifestyle
- sports
- technology
```