---
title: "reference-book/4-dataflows/filter"
source: reference-book
version: genesis-0-1-0
id: reference-book/4-dataflows/filter
canonical: /docs/reference-book/4-dataflows/filter
---


As we are progressing toward more advanced features, now is a good time to meet filter operator <<<@>>>.

We discussed the concept of frequency in introduction chapter. A vibration is wholding a layer around it and this layer is shaped from different frequencies. As data moves through the system it absorbs these frequencies.

Now using a filter operator we can filter the incoming vibration and only pass those who fulfill our filter policy. If the incoming vibration has the specified frequency, then it will pass through.

```
$x
$y 

(10 x,20 y) $pointA

pointA @x ? // 10 

```

This operator is still a work in progress and more features will be added to it in future releases. It is a mechanism to quickly pick what we need from incoming data.