%
%    This example code illustrates how to access and visualize LaRC
%  CERES ES8 NPP HDF4 Grid file in MATLAB. 
%
%   If you have any questions, suggestions, 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 (without .m at the end)
%
%  $matlab -nosplash -nodesktop -r CER_ES8_NPP_FM5_Edition2_203209_20220131_hdf
%
% Tested under: MATLAB R2021a
% Last updated: 2022-11-29

import matlab.io.hdf4.*

% Open the HDF-EOS2 Grid file.
FILE_NAME='CER_ES8_NPP-FM5_Edition2_203209.20220131.hdf';
DATAFIELD_NAME='CERES LW flux at TOA';

SD_id = sd.start(FILE_NAME, 'rdonly');
sds_index = sd.nameToIndex(SD_id, DATAFIELD_NAME);
sds_id = sd.select(SD_id, sds_index);
data = sd.readData(sds_id);

% Read _FillValue from data field.
fillvalue_index = sd.findAttr(sds_id, '_FillValue');
fillvalue = sd.readAttr(sds_id, fillvalue_index);

% Get the long name from data field.
long_name_index = sd.findAttr(sds_id, 'long_name');
long_name = sd.readAttr(sds_id, long_name_index);

% Read units from the data field.
units_index = sd.findAttr(sds_id, 'units');
units = sd.readAttr(sds_id, units_index);

% Terminate access to the corresponding data set.
sd.endAccess(sds_id);

% Read lat.
sds_index = sd.nameToIndex(SD_id, 'Colatitude of CERES FOV at TOA');
sds_id = sd.select(SD_id, sds_index);
colat = sd.readData(sds_id);
sd.endAccess(sds_id);

% Read lon.
sds_index = sd.nameToIndex(SD_id, 'Longitude of CERES FOV at TOA');
sds_id = sd.select(SD_id, sds_index);
lon = sd.readData(sds_id);
sd.endAccess(sds_id);

% Close the file.
sd.close(SD_id);

% Convert the data to double type for plot.
data = double(data);
lon = double(lon);
colat = double(colat);

% Replace the fill value with NaN.
data(data==fillvalue) = NaN;
colat(data==fillvalue) = NaN;
lon(data==fillvalue) = NaN;

% Convert colat to lat.
lat = 90 - colat;

% Plot the data using surfm and axesm.
f = figure('Name', FILE_NAME, 'visible', 'off');
axesm('MapProjection','eqdcylin', ...
      'Frame','on','Grid','on', ...
      'FontSize', 8, ...
      'MeridianLabel','on','ParallelLabel','on',...
      'MLabelParallel','south');
coast = load('coastlines.mat');
scatterm(lat(:), lon(:), 1, data(:));
plotm(coast.coastlat, coast.coastlon,'k');

% Put color bar.
colormap('Jet');
h=colorbar();

% Set unit.
set (get(h, 'title'), 'string', units);
tightmap;

% Put title. 
tstring = {FILE_NAME; long_name};
title(tstring, 'Interpreter', 'none', 'FontSize', 10, ...
      'FontWeight','bold');
saveas(f,[FILE_NAME '.m.png']);
exit;