.. DO NOT EDIT.
.. THIS FILE WAS AUTOMATICALLY GENERATED BY SPHINX-GALLERY.
.. TO MAKE CHANGES, EDIT THE SOURCE PYTHON FILE:
.. "gallery/Contours/NCL_lb_3.py"
.. LINE NUMBERS ARE GIVEN BELOW.

.. only:: html

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

        :ref:`Go to the end <sphx_glr_download_gallery_Contours_NCL_lb_3.py>`
        to download the full example code.

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

.. _sphx_glr_gallery_Contours_NCL_lb_3.py:


NCL_lb_3.py
===============
This script illustrates the following concepts:
   - Drawing a horizontal colorbar
   - Changing the colorbar labels
   - Changing the angle of colorbar labels
   - Changing the font size of the colorbar's labels
   - Adding a title to a colorbar
   - Adjusting colorbar position relavtive to  plot axes

See following URLs to see the reproduced NCL plot & script:
    - Original NCL script: https://www.ncl.ucar.edu/Applications/Scripts/lb_3.ncl
    - Original NCL plot: https://www.ncl.ucar.edu/Applications/Images/lb_3_lg.png

.. GENERATED FROM PYTHON SOURCE LINES 18-19

Import packages:

.. GENERATED FROM PYTHON SOURCE LINES 19-30

.. code-block:: Python


    import numpy as np
    import xarray as xr
    import cartopy.crs as ccrs
    from cartopy.mpl.gridliner import LongitudeFormatter, LatitudeFormatter
    import matplotlib.pyplot as plt
    import cmaps

    import geocat.datafiles as gdf
    import geocat.viz as gv








.. GENERATED FROM PYTHON SOURCE LINES 31-32

Read in data:

.. GENERATED FROM PYTHON SOURCE LINES 32-42

.. code-block:: Python


    # Open a netCDF data file using xarray default engine and load the data into xarrays
    ds = xr.open_dataset(gdf.get("netcdf_files/atmos.nc"), decode_times=False)

    # Extract slice of data
    V = ds.V.isel(time=0, lev=3)

    # Fix the artifact of not-shown-data around 0 and 360-degree longitudes
    V = gv.xr_add_cyclic_longitudes(V, "lon")








.. GENERATED FROM PYTHON SOURCE LINES 43-44

Plot:

.. GENERATED FROM PYTHON SOURCE LINES 44-125

.. code-block:: Python


    # Generate figure (set its size (width, height) in inches)
    fig = plt.figure(figsize=(10, 6))

    # Generate axes using Cartopy and draw coastlines
    ax = plt.axes(projection=ccrs.PlateCarree())
    ax.coastlines(linewidths=0.5, alpha=0.6)

    # Use geocat.viz.util convenience function to set axes limits & tick values
    gv.set_axes_limits_and_ticks(
        ax,
        xlim=(-180, 180),
        ylim=(-90, 90),
        xticks=np.linspace(-180, 180, 13),
        yticks=np.linspace(-90, 90, 7),
    )

    # Use geocat.viz.util convenience function to add minor and major tick lines
    gv.add_major_minor_ticks(ax, labelsize=10)

    # Use geocat.viz.util convenience function to make latitude, longitude tick labels
    gv.add_lat_lon_ticklabels(ax)
    # Remove degree symbol from tick labels
    ax.yaxis.set_major_formatter(LatitudeFormatter(degree_symbol=''))
    ax.xaxis.set_major_formatter(LongitudeFormatter(degree_symbol=''))

    # Use geocat.viz.util convenience function to add titles
    gv.set_titles_and_labels(
        ax,
        lefttitle=V.long_name,
        righttitle=V.units,
        lefttitlefontsize=12,
        righttitlefontsize=12,
    )

    # Import an NCL colormap
    cmap = cmaps.wgne15

    # Specify which contour levels to draw
    contour_lev = np.arange(-20, 28, 4)
    # Plot filled contour
    contour = V.plot.contourf(
        ax=ax,
        transform=ccrs.PlateCarree(),
        cmap=cmap,
        levels=contour_lev,
        add_colorbar=False,
        add_labels=False,
    )
    # Plot line contour
    V.plot.contour(
        ax=ax,
        transform=ccrs.PlateCarree(),
        colors='black',
        linewidths=0.5,
        linestyles='solid',
        levels=contour_lev,
        add_colorbar=False,
        add_labels=False,
    )

    # Create horizontal colorbar
    # By changing the kwarg `pad`, the colorbar can be moved closer to or farther away from
    # the axis parallel to it.
    # `pad` defaults to 0.15 for horizontal colorbars
    # `extendrect` and `extendfrac` format the ends of the colorbar, default is
    # pointed ends to show there are values beyond the given contour levels
    cbar = plt.colorbar(
        contour,
        ax=ax,
        orientation='horizontal',
        shrink=0.75,
        pad=0.11,
        extendrect=True,
        extendfrac='auto',
    )
    # Make colorbar tick labels larger and rotate them
    cbar.ax.tick_params(labelsize=14, rotation=45)
    # Format colorbar title, this will make the title appear above the colorbar
    cbar.ax.set_title('Default position for color bar title', fontsize=10)
    plt.show()



.. image-sg:: /gallery/Contours/images/sphx_glr_NCL_lb_3_001.png
   :alt: meridional wind component, m/s, Default position for color bar title
   :srcset: /gallery/Contours/images/sphx_glr_NCL_lb_3_001.png
   :class: sphx-glr-single-img






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

   **Total running time of the script:** (0 minutes 0.277 seconds)


.. _sphx_glr_download_gallery_Contours_NCL_lb_3.py:

.. only:: html

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

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

      :download:`Download Jupyter notebook: NCL_lb_3.ipynb <NCL_lb_3.ipynb>`

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

      :download:`Download Python source code: NCL_lb_3.py <NCL_lb_3.py>`

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

      :download:`Download zipped: NCL_lb_3.zip <NCL_lb_3.zip>`


.. only:: html

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

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