"""
Copyright (C) 2014 John Evans

This example code illustrates how to access and visualize a LaRC TES O3 Nadir
HDF-EOS5 Swath file in Python.

If you have any questions, suggestions, or comments on this example, please use
the HDF-EOS Forum (http://hdfeos.org/forums).  If you would like to see an
example of any other NASA HDF/HDF-EOS data product that is not listed in the
HDF-EOS Comprehensive Examples page (http://hdfeos.org/zoo), feel free to
contact us at eoshelp@hdfgroup.org or post it at the HDF-EOS Forum
(http://hdfeos.org/forums).

Usage:  save this script and run

    $python TES-Aura_L2-O3-Nadir_r0000002433_F08_12.he5.py

The HDF file must in your current working directory.

Tested under: Python 3.9.1::Miniconda
Last updated: 2021-11-29
"""

import os
import h5py
import numpy as np
import matplotlib as mpl
import matplotlib.pyplot as plt
from mpl_toolkits.basemap import Basemap

FILE_NAME = 'TES-Aura_L2-O3-Nadir_r0000002433_F08_12.he5'
with h5py.File(FILE_NAME, mode='r') as f:
    name = '/HDFEOS/SWATHS/O3NadirSwath/Data Fields/O3'
    data = f[name][:, 5]
    units = f[name].attrs['Units'].decode()
    longname = f[name].attrs['Title'].decode()
    fillvalue = f[name].attrs['_FillValue']

    data[data == fillvalue] = np.nan

    # Get the geolocation data
    latitude = f['/HDFEOS/SWATHS/O3NadirSwath/Geolocation Fields/Latitude'][:]
    longitude = f['/HDFEOS/SWATHS/O3NadirSwath/Geolocation Fields/Longitude'][:]

    m = Basemap(projection='cyl', resolution='l',
                llcrnrlat=-90, urcrnrlat=90,
                llcrnrlon=-180, urcrnrlon=180)
    m.drawcoastlines(linewidth=0.5)
    m.drawparallels(np.arange(-90, 91, 45))
    m.drawmeridians(np.arange(-180, 180, 45), labels=[True,False,False,True])
    m.scatter(longitude, latitude, c=data, s=1, cmap=plt.cm.jet,
            edgecolors=None, linewidth=0)
    cb = m.colorbar()
    cb.set_label(units)

    basename = os.path.basename(FILE_NAME)
    plt.title('{0}\n{1} at nLevels=5'.format(basename, longname))
    fig = plt.gcf()
    pngfile = "{0}.py.png".format(basename)
    fig.savefig(pngfile)