> For the complete documentation index, see [llms.txt](https://docs.os.uk/more-than-maps/llms.txt). Markdown versions of documentation pages are available by appending `.md` to page URLs; this page is available as [Markdown](https://docs.os.uk/more-than-maps/advanced-applications/os-ngd-data-in-dashboards/os-power-bi-map-visual/os-power-bi-map-visual-getting-started-guide/using-the-lasso-tool-on-the-map-to-filter-data.md).

# Using the lasso tool on the map to filter data

The visual has been designed so that clicking on a point or polygon on the map displays a pop-up with additional useful information about that location instead of filtering data in other visuals on the page.

{% hint style="info" %}
We have chosen this approach, rather than using the in-built Power BI tooltips, in order to support situations such as overlapping features (with paginated pop-ups)
{% endhint %}

Instead of clicking to select features, the lasso tool allows you to filter the data on other visuals based on a selection taken from the map.

To use the lasso tool:

{% stepper %}
{% step %}

### Select the lasso icon

Select the lasso tool by clicking on the *lasso icon* in the top right of the map.

Your cursor should change shape once the lasso button has been clicked.

{% hint style="info" %}
Note, the lasso tool is only available when the visual is receiving unfiltered data from Power BI. If another visual is already filtering or slicing the data, the lasso tool will be unavailable.
{% endhint %}
{% endstep %}

{% step %}

### Select the data you want

Draw a ‘lasso’ by holding down the left mouse button and dragging the cursor around all the points / polygons that you want to filter the other visualisations on the page by.

A cyan-coloured shape will be created during the process.
{% endstep %}

{% step %}

### Release the left mouse button

Once you’re happy with your selection, release the left mouse button.

Any points / polygons completely within the boundaries of the lasso shape created will now be highlighted cyan and the other visualisations on the page will be update reflecting the selection made.

<figure><img src="/files/45f063fe6a2fadfef3e367d8096a48b733bdc880" alt="A screenshot showing data selected using the lasso tool"><figcaption><p>An example of data selected using the lasso tool.</p></figcaption></figure>

{% hint style="info" %}

#### Maximum number of data points

The lasso tool can only select up to 500 different data points on the map at a time to ensure adequate performance.
{% endhint %}
{% endstep %}
{% endstepper %}


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