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

.. _gallery_beckers_barley_trellis_plot:


Becker's Barley Trellis Plot
----------------------------
The example demonstrates the trellis charts created by Richard Becker, William Cleveland and others in the 1990s. Using the visualization technique below they identified an anomoly in a widely used agriculatural dataset, which they termed `"The Morris Mistake." <http://ml.stat.purdue.edu/stat695t/writings/Trellis.User.pdf>`_. It became their favored way of showcasing the power of this pioneering plot.


.. altair-plot::
    :code-below:

    
    import altair as alt
    from vega_datasets import data

    source = data.barley()

    alt.Chart(source, title="The Morris Mistake").mark_point().encode(
        alt.X(
            'yield:Q',
            title="Barley Yield (bushels/acre)",
            scale=alt.Scale(zero=False),
            axis=alt.Axis(grid=False)
        ),
        alt.Y(
            'variety:N',
            title="",
            sort='-x',
            axis=alt.Axis(grid=True)
        ),
        color=alt.Color('year:N', legend=alt.Legend(title="Year")),
        row=alt.Row(
            'site:N',
            title="",
            sort=alt.EncodingSortField(field='yield', op='sum', order='descending'),
        )
    ).properties(
        height=alt.Step(20)
    ).configure_view(stroke="transparent")


.. toctree::
   :hidden: