:orphan:
:html_theme.sidebar_secondary.remove:

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

.. _gallery_density_stack:


Stacked Density Estimates
-------------------------
To plot a stacked graph of estimates, use a shared ``extent`` and a fixed
number of subdivision ``steps`` to ensure that the points for each area align
well.  Density estimates of measurements for each iris flower feature are plot
in a stacked method.  In addition, setting ``counts`` to true multiplies the
densities by the number of data points in each group, preserving proportional
differences.


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



    import altair as alt
    from vega_datasets import data

    source = data.iris()

    alt.Chart(source).transform_fold(
        ['petalWidth', 
         'petalLength', 
         'sepalWidth', 
         'sepalLength'], 
        as_ = ['Measurement_type', 'value']
    ).transform_density(
        density='value', 
        bandwidth=0.3, 
        groupby=['Measurement_type'], 
        extent= [0, 8], 
        counts = True, 
        steps=200
    ).mark_area().encode(
        alt.X('value:Q'), 
        alt.Y('density:Q', stack='zero'),
        alt.Color('Measurement_type:N')
    ).properties(width=400, height=100)


.. tab-set::

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

        .. code:: python



            import altair as alt
            from vega_datasets import data

            source = data.iris()

            alt.Chart(source).transform_fold(
                ['petalWidth', 
                 'petalLength', 
                 'sepalWidth', 
                 'sepalLength'], 
                as_ = ['Measurement_type', 'value']
            ).transform_density(
                density='value', 
                bandwidth=0.3, 
                groupby=['Measurement_type'], 
                extent= [0, 8], 
                counts = True, 
                steps=200
            ).mark_area().encode(
                alt.X('value:Q'), 
                alt.Y('density:Q').stack('zero'),
                alt.Color('Measurement_type:N')
            ).properties(width=400, height=100)


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

        .. code:: python



            import altair as alt
            from vega_datasets import data

            source = data.iris()

            alt.Chart(source).transform_fold(
                ['petalWidth', 
                 'petalLength', 
                 'sepalWidth', 
                 'sepalLength'], 
                as_ = ['Measurement_type', 'value']
            ).transform_density(
                density='value', 
                bandwidth=0.3, 
                groupby=['Measurement_type'], 
                extent= [0, 8], 
                counts = True, 
                steps=200
            ).mark_area().encode(
                alt.X('value:Q'), 
                alt.Y('density:Q', stack='zero'),
                alt.Color('Measurement_type:N')
            ).properties(width=400, height=100)