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

.. _gallery_trail_marker:


Line Chart with Varying Size
----------------------------
This is example of using the ``trail`` marker to vary the size of a line.


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

    
    import altair as alt
    from vega_datasets import data

    source = data.wheat()

    alt.Chart(source).mark_trail().encode(
        x='year:T',
        y='wheat:Q',
        size='wheat:Q'
    )


.. toctree::
   :hidden: