.. DO NOT EDIT.
.. THIS FILE WAS AUTOMATICALLY GENERATED BY SPHINX-GALLERY.
.. TO MAKE CHANGES, EDIT THE SOURCE PYTHON FILE:
.. "gallery/scalar_data/raster_reprojections.py"
.. LINE NUMBERS ARE GIVEN BELOW.

.. only:: html

    .. note::
        :class: sphx-glr-download-link-note

        :ref:`Go to the end <sphx_glr_download_gallery_scalar_data_raster_reprojections.py>`
        to download the full example code.

.. rst-class:: sphx-glr-example-title

.. _sphx_glr_gallery_scalar_data_raster_reprojections.py:


Raster reprojections
====================

When plotting raster data onto a map with `imshow`, we need to first set the
extent of the map so the reprojection is done correctly.

In this example, we have some raster data stored as a numpy array that is
referenced to a rectangular coordinate system (PlateCarree). Cartopy reprojects the
data to match the map's coordinate system based on the currently set map limits.
This means that the map extent/boundary must be set *before* `imshow` is called.

.. GENERATED FROM PYTHON SOURCE LINES 14-99



.. image-sg:: /gallery/scalar_data/images/sphx_glr_raster_reprojections_001.png
   :alt: ✗ Adding the raster BEFORE setting the map extent, ✓ Adding the raster AFTER setting the map extent
   :srcset: /gallery/scalar_data/images/sphx_glr_raster_reprojections_001.png
   :class: sphx-glr-single-img





.. code-block:: Python


    from matplotlib.patches import Rectangle
    import matplotlib.pyplot as plt
    import numpy as np

    import cartopy.crs as ccrs
    import cartopy.feature as cf


    def main():
        # Generate raster data as a numpy array
        img = np.linspace(0, 1, 10_000).reshape(100, 100)

        # Define the origin and extent of the image following matplotlib's
        # convention `(left, right, bottom, top)`. These are referenced to
        # a rectangular coordinate system.
        img_origin = "lower"
        img_extent = (-87.6, -86.4, 41.4, 42.0)
        img_proj = ccrs.PlateCarree()

        imshow_kwargs = dict(
            extent=img_extent,
            origin=img_origin,
            transform=img_proj,
            cmap="spring",
        )

        # Define extent and projection for the map
        map_extent = (-88.1, -86.1, 41.2, 42.2)
        map_proj = ccrs.RotatedPole(pole_longitude=120.0, pole_latitude=70.0)

        fig, axs = plt.subplots(
            nrows=1,
            ncols=2,
            figsize=(12, 5),
            subplot_kw={"projection": map_proj},
            sharex=True,
            sharey=True,
            layout="constrained",
        )

        # Adding the raster *before* setting the map extent
        ax = axs[0]
        ax.set_title("\u2717 Adding the raster\nBEFORE setting the map extent")

        ax.imshow(img, **imshow_kwargs)
        ax.set_extent(map_extent, crs=img_proj)

        # Adding the raster *after* setting the map extent
        ax = axs[1]
        ax.set_title("\u2713 Adding the raster\nAFTER setting the map extent")

        ax.set_extent(map_extent, crs=img_proj)
        ax.imshow(img, **imshow_kwargs)

        for ax in axs:
            # Add other map features
            ax.add_feature(cf.LAKES, alpha=0.6)
            ax.add_feature(cf.STATES)

            # Highlight raster boundaries
            xy = (img_extent[0], img_extent[2])
            width = img_extent[1] - img_extent[0]
            height = img_extent[3] - img_extent[2]
            ax.add_patch(
                Rectangle(
                    xy,
                    width,
                    height,
                    transform=img_proj,
                    edgecolor="black",
                    facecolor="None",
                    linewidth=3,
                    label="Raster data bounds",
                )
            )

            ax.legend()
            ax.gridlines(draw_labels=True, x_inline=False, dms=True)

        plt.show()


    if __name__ == "__main__":
        main()


.. rst-class:: sphx-glr-timing

   **Total running time of the script:** (0 minutes 12.809 seconds)


.. _sphx_glr_download_gallery_scalar_data_raster_reprojections.py:

.. only:: html

  .. container:: sphx-glr-footer sphx-glr-footer-example

    .. container:: sphx-glr-download sphx-glr-download-jupyter

      :download:`Download Jupyter notebook: raster_reprojections.ipynb <raster_reprojections.ipynb>`

    .. container:: sphx-glr-download sphx-glr-download-python

      :download:`Download Python source code: raster_reprojections.py <raster_reprojections.py>`

    .. container:: sphx-glr-download sphx-glr-download-zip

      :download:`Download zipped: raster_reprojections.zip <raster_reprojections.zip>`


.. only:: html

 .. rst-class:: sphx-glr-signature

    `Gallery generated by Sphinx-Gallery <https://sphinx-gallery.github.io>`_