# Filter time series

This filter allows you to keep or remove points in a time series based on a time range or mathematical conditions. The **Filter By Time** option filters data based on the timestamp of the data (the x-axis, in many cases), while the **Filter By Condition** filters based on the value of the data (the y-axis, in many cases). Only one of these sections needs to be filled out.

* To filter using an event set, use the [event indicator series card](../card-event-indicator-series/index.md) to generate a series that represents the count of events. Then set the [formula](../cards-formula-syntax/index.md) in the **Filter By Condition** option to filter to when your generated series is greater than zero.
* In the [formula](../cards-formula-syntax/index.md) for the **Filter By Condition** option, we use the *plot reference* to refer to a specific series (`$A`). This allows you to use multiple series in your filter condition (`$A > 100 && $B < 50`). We also use the '@' symbol to refer to any properties on the (optionally) selected object.
* There is a parameter to control whether to keep or remove the data that matches your filter condition.
* There is a **Filter Method** parameter with two options: **Gap** and **Continuous**.
  * If you choose **Gap**, data not matching your condition will be filtered out and will be shown as gaps in your series.
  * With **Continuous**, Quiver will interpolate between the filtered values to produce a continuous series. Interpolation settings are controlled by the **Interpolation Options** dropdowns, with default **Linear**.

[Learn more about how interpolation affects this operation.](../cards-interpolation-usage/index.md#filter-time-series)

## Input type

Time series

## Output type

Time series

## Examples

![Filter on time](../../../assets/935c4206baa3c24b15b12128e83a4077f91f0e02181d8901d10ef0161fba5ffc.webp)

![Filter on condition](../../../assets/f7395227f42abab97a7cf17c738e91b71aa8e1c981f1d23f9d22b24f456a3849.webp)

## Usage information

| Functionality | Availability |
| --- | --- |
| [Standard Quiver card](../core-concepts/index.md#cards) | Supported |
| [Transform table transform](../cards-transform-table/index.md) | Supported |