# Create a density map

{% hint style="success" %}
This is the official documentation of the `forestadmin-agent-django` and `forestadmin-agent-flask` Python agents.
{% endhint %}

![](/files/Lq6KEdfapAfX4pR8Jnh0)

This last example shows how you can achieve virtually anything since you are coding in a sandbox. There's no limit to what you can do with Smart Charts.

In this snippet, notice how we import the [D3js](https://d3js.org) library. Of course, you can choose to use any other library of your choice.

{% hint style="info" %}
This density map chart is inspired by [this one](https://observablehq.com/@d3/bubble-map).
{% endhint %}

The resulting chart can be resized to fit your use.

{% tabs %}
{% tab title="Agent" %}

{% endtab %}

{% tab title="Component" %}

```js
/* eslint-disable */

import Component from '@glimmer/component';
import { loadExternalJavascript } from 'client/utils/smart-view-utils';
import { action } from '@ember/object';
import { tracked } from '@glimmer/tracking';
import { inject as service } from '@ember/service';

// Settings
const height = 610;
const width = 975;

export default class extends Component {
  @service lianaServerFetch;
  @tracked chart;

  constructor(...args) {
    super(...args);

    this.load();
  }

  async load() {
    // Load charting library
    await loadExternalJavascript('https://d3js.org/d3.v6.min.js');
    await loadExternalJavascript('https://unpkg.com/topojson-client@3');

    // Load data from agent
    const response = await this.lianaServerFetch.fetch(
      '/forest/_charts/densitymap',
      {},
    );
    const data = await response.json();

    // Render chart
    this.renderChart(data.contours, data.population);
  }

  @action
  async renderChart(us, population) {
    // Format data
    const format = d3.format(',.0f');
    const path = d3.geoPath();

    const features = new Map(
      topojson.feature(us, us.objects.counties).features.map(d => [d.id, d]),
    );

    const data = population.slice(1).map(([population, state, county]) => {
      const id = state + county;
      const feature = features.get(id);
      return {
        id,
        position: feature && path.centroid(feature),
        title: feature && feature.properties.name,
        value: +population,
      };
    });

    const radius = d3.scaleSqrt([0, d3.max(data, d => d.value)], [0, 40]);

    // Render SVG
    const svg = d3.create('svg').attr('viewBox', [0, 0, width, height]);

    svg
      .append('path')
      .datum(topojson.feature(us, us.objects.nation))
      .attr('fill', '#ddd')
      .attr('d', path);

    svg
      .append('path')
      .datum(topojson.mesh(us, us.objects.states, (a, b) => a !== b))
      .attr('fill', 'none')
      .attr('stroke', 'white')
      .attr('stroke-linejoin', 'round')
      .attr('d', path);

    const legend = svg
      .append('g')
      .attr('fill', '#777')
      .attr('transform', 'translate(915,608)')
      .attr('text-anchor', 'middle')
      .style('font', '10px sans-serif')
      .selectAll('g')
      .data(radius.ticks(4).slice(1))
      .join('g');

    legend
      .append('circle')
      .attr('fill', 'none')
      .attr('stroke', '#ccc')
      .attr('cy', d => -radius(d))
      .attr('r', radius);

    legend
      .append('text')
      .attr('y', d => -2 * radius(d))
      .attr('dy', '1.3em')
      .text(radius.tickFormat(4, 's'));

    svg
      .append('g')
      .attr('fill', 'brown')
      .attr('fill-opacity', 0.5)
      .attr('stroke', '#fff')
      .attr('stroke-width', 0.5)
      .selectAll('circle')
      .data(
        data.filter(d => d.position).sort((a, b) => d3.descending(a.value, b.value)),
      )
      .join('circle')
      .attr('transform', d => `translate(${d.position})`)
      .attr('r', d => radius(d.value))
      .append('title')
      .text(d => `${d.title} ${format(d.value)}`);

    this.chart = svg.node();
  }
}
```

{% endtab %}

{% tab title="Template" %}

```handlebars
<div class='c-smart-view'>{{this.chart}}</div>
```

{% endtab %}
{% endtabs %}


---

# Agent Instructions: Querying This Documentation

If you need additional information that is not directly available in this page, you can query the documentation dynamically by asking a question.

Perform an HTTP GET request on the current page URL with the `ask` query parameter:

```
GET https://docs.forestadmin.com/developer-guide-agents-python/frontend-customization/smart-charts/create-a-density-map.md?ask=<question>
```

The question should be specific, self-contained, and written in natural language.
The response will contain a direct answer to the question and relevant excerpts and sources from the documentation.

Use this mechanism when the answer is not explicitly present in the current page, you need clarification or additional context, or you want to retrieve related documentation sections.