:orphan:
:html_theme.sidebar_secondary.remove:

.. This document is auto-generated by the altair-gallery extension. Do not modify directly.

.. _gallery_choropleth:


Choropleth Map
==============
A choropleth map of unemployment rate per county in the US


.. altair-plot::
    :remove-code:
    


    import altair as alt
    from vega_datasets import data

    counties = alt.topo_feature(data.us_10m.url, 'counties')
    source = data.unemployment.url

    alt.Chart(counties).mark_geoshape().encode(
        color='rate:Q'
    ).transform_lookup(
        lookup='id',
        from_=alt.LookupData(source, 'id', ['rate'])
    ).project(
        type='albersUsa'
    ).properties(
        width=500,
        height=300
    )
    # No channel encoding options are specified in this chart
    # so the code is the same as for the method-based syntax.


.. tab-set::

    .. tab-item:: Method syntax
        :sync: method

        .. code:: python


            import altair as alt
            from vega_datasets import data

            counties = alt.topo_feature(data.us_10m.url, 'counties')
            source = data.unemployment.url

            alt.Chart(counties).mark_geoshape().encode(
                color='rate:Q'
            ).transform_lookup(
                lookup='id',
                from_=alt.LookupData(source, 'id', ['rate'])
            ).project(
                type='albersUsa'
            ).properties(
                width=500,
                height=300
            )


    .. tab-item:: Attribute syntax
        :sync: attribute

        .. code:: python


            import altair as alt
            from vega_datasets import data

            counties = alt.topo_feature(data.us_10m.url, 'counties')
            source = data.unemployment.url

            alt.Chart(counties).mark_geoshape().encode(
                color='rate:Q'
            ).transform_lookup(
                lookup='id',
                from_=alt.LookupData(source, 'id', ['rate'])
            ).project(
                type='albersUsa'
            ).properties(
                width=500,
                height=300
            )
            # No channel encoding options are specified in this chart
            # so the code is the same as for the method-based syntax.