# Filtering and splitting by tag in a workbook

Filter a [workbook](https://dev.nominal.io/platform/reference/glossary.md#workbook "Where you analyze time-series data from assets and runs, in tabs and panels, after a test or live.") by [tag](https://dev.nominal.io/platform/reference/glossary.md#tag "A key-value pair on your data points, such as motor_id: 1, that lets you filter a subset of points from a single dataset.") to show only the points with certain values, or split by a tag to plot each value as its own series.

## In the Nominal app

To filter a single variable by tag with a transform, see [🔒︎Using variables with tags](https://docs.nominal.io/core/documentation/platform/workbooks/manipulating-time-series#using-variables-with-tags).

### Filter by a tag

Show only the points with certain tag values:

1. In the workbook’s left sidebar, click the **Data** icon to open the **DATA** panel.
2. In its **TAG FILTERS** section, click **+** (**Add tag filter**). Choose the **Tag key**, pick the values under **Tag values**, and click **ADD TAG FILTER**.
3. On the filter’s row, after **Apply to**, click **TAB** to filter every [variable](https://dev.nominal.io/platform/reference/glossary.md#variable "A reference to a channel, with any tag filters, splits, and transforms applied, or a formula built from other variables. Workbooks plot variables, and checklists check them.") in the current tab, or **WORKBOOK** for every variable in the workbook.

![The TAG FILTERS section with one filter set and Apply to TAB or WORKBOOK, and the Add tag filter popover choosing a Tag key and its Tag values](https://dev.nominal.io/quickstart/_images/workbook-tag-filter.png)

### Split by a tag

Plot each tag value as its own series by splitting the variable that plots the channel:

1. In the left sidebar’s **Channels & variables** view, find the **VARIABLES** section, hover over the variable, and click its **Transform** icon.
2. In the **Transform** window, click the settings icon on the **Series** row.
3. In the **Series** window, choose the tag under **Split by tags**, and click **APPLY**.

![Arrows from a channel under CHANNELS to its variable under VARIABLES, then from the variable's Transform icon to the Transform window, and from its Series settings icon to Split by tags and APPLY in the Series panel](https://dev.nominal.io/quickstart/_images/workbook-split-by-tags.png)

## In code

To filter by tag in code, pass the tags when you pull the data, as in [Pull data into your code](https://dev.nominal.io/platform/data-model/paradigms/stories/post-test.md#pull-data-into-your-code).