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

.. only:: html

    .. meta::
        :keywords: codex

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

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

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

.. _sphx_glr_gallery_axisartist_demo_curvelinear_grid.py:


=====================
Curvilinear grid demo
=====================

Custom grid and ticklines.

This example demonstrates how to use
`~.grid_helper_curvelinear.GridHelperCurveLinear` to define custom grids and
ticklines by applying a transformation on the grid.  This can be used, as
shown on the second plot, to create polar projections in a rectangular box.

.. GENERATED FROM PYTHON SOURCE LINES 13-113



.. image-sg:: /gallery/axisartist/images/sphx_glr_demo_curvelinear_grid_001.png
   :alt: demo curvelinear grid
   :srcset: /gallery/axisartist/images/sphx_glr_demo_curvelinear_grid_001.png, /gallery/axisartist/images/sphx_glr_demo_curvelinear_grid_001_2_00x.png 2.00x
   :class: sphx-glr-single-img





.. code-block:: Python


    import matplotlib.pyplot as plt
    import numpy as np

    from matplotlib.projections import PolarAxes
    from matplotlib.transforms import Affine2D
    from mpl_toolkits.axisartist import Axes, HostAxes, angle_helper
    from mpl_toolkits.axisartist.grid_helper_curvelinear import \
        GridHelperCurveLinear


    def curvelinear_test1(fig):
        """
        Grid for custom transform.
        """

        def tr(x, y): return x, y - x
        def inv_tr(x, y): return x, y + x

        grid_helper = GridHelperCurveLinear((tr, inv_tr))

        ax1 = fig.add_subplot(1, 2, 1, axes_class=Axes, grid_helper=grid_helper)
        # ax1 will have ticks and gridlines defined by the given transform (+
        # transData of the Axes).  Note that the transform of the Axes itself
        # (i.e., transData) is not affected by the given transform.
        xx, yy = tr(np.array([3, 6]), np.array([5, 10]))
        ax1.plot(xx, yy)

        ax1.set_aspect(1)
        ax1.set_xlim(0, 10)
        ax1.set_ylim(0, 10)

        ax1.axis["t"] = ax1.new_floating_axis(0, 3)
        ax1.axis["t2"] = ax1.new_floating_axis(1, 7)
        ax1.grid(True, zorder=0)


    def curvelinear_test2(fig):
        """
        Polar projection, but in a rectangular box.
        """

        # PolarAxes.PolarTransform takes radian. However, we want our coordinate
        # system in degree
        tr = Affine2D().scale(np.pi/180, 1) + PolarAxes.PolarTransform(
            apply_theta_transforms=False)
        # Polar projection, which involves cycle, and also has limits in
        # its coordinates, needs a special method to find the extremes
        # (min, max of the coordinate within the view).
        extreme_finder = angle_helper.ExtremeFinderCycle(
            nx=20, ny=20,  # Number of sampling points in each direction.
            lon_cycle=360, lat_cycle=None,
            lon_minmax=None, lat_minmax=(0, np.inf),
        )
        # Find grid values appropriate for the coordinate (degree, minute, second).
        grid_locator1 = angle_helper.LocatorDMS(12)
        # Use an appropriate formatter.  Note that the acceptable Locator and
        # Formatter classes are a bit different than that of Matplotlib, which
        # cannot directly be used here (this may be possible in the future).
        tick_formatter1 = angle_helper.FormatterDMS()

        grid_helper = GridHelperCurveLinear(
            tr, extreme_finder=extreme_finder,
            grid_locator1=grid_locator1, tick_formatter1=tick_formatter1)
        ax1 = fig.add_subplot(
            1, 2, 2, axes_class=HostAxes, grid_helper=grid_helper)

        # make ticklabels of right and top axis visible.
        ax1.axis["right"].major_ticklabels.set_visible(True)
        ax1.axis["top"].major_ticklabels.set_visible(True)
        # let right axis shows ticklabels for 1st coordinate (angle)
        ax1.axis["right"].get_helper().nth_coord_ticks = 0
        # let bottom axis shows ticklabels for 2nd coordinate (radius)
        ax1.axis["bottom"].get_helper().nth_coord_ticks = 1

        ax1.set_aspect(1)
        ax1.set_xlim(-5, 12)
        ax1.set_ylim(-5, 10)

        ax1.grid(True, zorder=0)

        # A parasite Axes with given transform
        ax2 = ax1.get_aux_axes(tr)
        # note that ax2.transData == tr + ax1.transData
        # Anything you draw in ax2 will match the ticks and grids of ax1.
        ax2.plot(np.linspace(0, 30, 51), np.linspace(10, 10, 51), linewidth=2)

        ax2.pcolor(np.linspace(0, 90, 4), np.linspace(0, 10, 4),
                   np.arange(9).reshape((3, 3)))
        ax2.contour(np.linspace(0, 90, 4), np.linspace(0, 10, 4),
                    np.arange(16).reshape((4, 4)), colors="k")


    if __name__ == "__main__":
        fig = plt.figure(figsize=(7, 4))

        curvelinear_test1(fig)
        curvelinear_test2(fig)

        plt.show()


.. _sphx_glr_download_gallery_axisartist_demo_curvelinear_grid.py:

.. only:: html

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

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

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

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

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

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

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


.. only:: html

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

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