.. _example_contour:

================================
Contour plots and Contour Levels
================================

Use the ``contour``-shape to draw contour-plots of regular (or irregular data)
or to indicate contour-levels on top of other plots.

(requires EOmaps >= v7.1)


.. image:: /_static/example_images/example_contour.png
    :width: 75%
    :align: center

.. code-block:: python

    # EOmaps example:  Contour plots and contour levels

    from eomaps import Maps
    import numpy as np

    # ------------- setup some random data
    lon, lat = np.meshgrid(np.linspace(-180, 180, 200), np.linspace(-90, 90, 100))
    data = np.sqrt(lon**2 + lat**2)
    name = "some parameter"

    # ------------- left map
    m = Maps(ax=121)
    m.add_title("Raster plot with contour-levels")
    m.add_feature.preset.coastline()
    # plot raster-data
    m.set_data(data, lon, lat, parameter=name)
    m.set_shape.raster()
    m.plot_map()

    # layer to indicate contour-levels
    m_cont = m.new_layer(inherit_data=True)
    m_cont.set_shape.contour(filled=False)
    m_cont.set_classify.EqualInterval(k=4)
    m_cont.plot_map(colors=("r", "g", "b", "m"))

    # ------------- right map
    m2 = m.new_map(ax=122, inherit_data=True)
    m2.add_title("Filled contour plot")
    m2.set_classify.EqualInterval(k=4)
    m2.set_shape.contour(filled=True)
    m2.plot_map(cmap="viridis")

    # add a colorbar and indicate contour-levels
    cb = m.add_colorbar(label="Data histogram with indicated contour levels highlighted.")
    cb.indicate_contours(m_cont)

    # apply a customized layout
    layout = {
        "figsize": [8.34, 3.9],
        "0_map": [0.03652, 0.44167, 0.45, 0.48115],
        "1_map": [0.51152, 0.44167, 0.45, 0.48115],
        "2_cb": [-0.0125, 0.02673, 1.0125, 0.28055],
        "2_cb_histogram_size": 0.76,
    }
    m.apply_layout(layout)
    m.show()