.. DO NOT EDIT.
.. THIS FILE WAS AUTOMATICALLY GENERATED BY SPHINX-GALLERY.
.. TO MAKE CHANGES, EDIT THE SOURCE PYTHON FILE:
.. "gallery/Bar/NCL_bar_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_Bar_NCL_bar_3.py>`
        to download the full example code.

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

.. _sphx_glr_gallery_Bar_NCL_bar_3.py:


NCL_bar_3.py
============
This script illustrates the following concepts:
    - Drawing bars instead of curves in an XY plot
    - Changing the width of the bars in a bar plot
    - Drawing filled bars up or down based on a Y reference value
    - Setting the minimum/maximum value of the Y axis in a bar plot

See following URLs to see the reproduced NCL plot & script:
    - Original NCL script: https://www.ncl.ucar.edu/Applications/Scripts/bar_3.ncl
    - Original NCL plot: https://www.ncl.ucar.edu/Applications/Images/bar_3_lg.png

.. GENERATED FROM PYTHON SOURCE LINES 16-17

Import packages

.. GENERATED FROM PYTHON SOURCE LINES 17-25

.. code-block:: Python


    import numpy as np
    import xarray as xr
    import matplotlib.pyplot as plt

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








.. GENERATED FROM PYTHON SOURCE LINES 26-27

Read in data:

.. GENERATED FROM PYTHON SOURCE LINES 27-43

.. 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/soi.nc"))
    dsoik = ds.DSOI_KET
    date = ds.date
    num_months = np.shape(date)[0]

    # Dates in the file are represented by year and month (YYYYMM)
    # representing them fractionally will make plotting the data easier
    # This produces the same results as NCL's yyyymm_to_yyyyfrac() function
    date_frac = np.empty_like(date)
    for n in np.arange(0, num_months, 1):
        yyyy = int(date[n] / 100)
        mon = (date[n] / 100 - yyyy) * 100
        date_frac[n] = yyyy + (mon - 1) / 12








.. GENERATED FROM PYTHON SOURCE LINES 44-45

Plot

.. GENERATED FROM PYTHON SOURCE LINES 45-83

.. code-block:: Python


    # Generate figure (set its size (width, height) in inches) and axes
    plt.figure(figsize=(12, 6))
    ax = plt.axes()

    # Create a list of colors based on the color bar values
    colors = ['red' if (value > 0) else 'blue' for value in dsoik[::8]]

    # Plot bar chart with defined width
    plt.bar(date_frac[::8], dsoik[::8], color=colors, width=0.25)

    # Use geocat.viz.util convenience function to add minor and major tick lines
    gv.add_major_minor_ticks(ax, x_minor_per_major=4, y_minor_per_major=5, labelsize=16)

    # Use geocat.viz.util convenience function to set axes parameters
    gv.set_axes_limits_and_ticks(
        ax,
        ylim=(-3, 3),
        yticks=np.linspace(-3, 3, 7),
        yticklabels=np.linspace(-3, 3, 7),
        xlim=(date_frac[40], date_frac[-16]),
        xticks=np.linspace(1900, 1980, 5),
    )

    # Use geocat.viz.util convenience function to set titles and labels
    gv.set_titles_and_labels(
        ax,
        maintitle="Darwin Southern Oscillation Index",
        ylabel='Anomalies',
        maintitlefontsize=36,
        labelfontsize=20,
    )

    # Plot horizontal line as a reference
    plt.hlines(0, 1880, 2000, colors="black", linewidth=0.6)

    plt.tight_layout()
    plt.show()



.. image-sg:: /gallery/Bar/images/sphx_glr_NCL_bar_3_001.png
   :alt: Darwin Southern Oscillation Index
   :srcset: /gallery/Bar/images/sphx_glr_NCL_bar_3_001.png
   :class: sphx-glr-single-img






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

   **Total running time of the script:** (0 minutes 0.570 seconds)


.. _sphx_glr_download_gallery_Bar_NCL_bar_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_bar_3.ipynb <NCL_bar_3.ipynb>`

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

      :download:`Download Python source code: NCL_bar_3.py <NCL_bar_3.py>`

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

      :download:`Download zipped: NCL_bar_3.zip <NCL_bar_3.zip>`


.. only:: html

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

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