%
%  This example code illustrates how to access and visualize TRMM version 7
% 2A25 HDF4 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 TRMM_2A25_20150401_98987_7_HDF
%
% Tested under: MATLAB R2020a
% Last updated: 2020-06-25
%
% Acknowledgement
%
%  Part of this example code is provided by
%  Kelly Luekemeyer, Mapping Toolbox Development, MathWorks, Inc.
import matlab.io.hdf4.*

% Open the HDF4 File
file_name='2A25.20150401.98987.7.HDF';
sd_id = sd.start(file_name, 'rdonly');

% Read data.
datafield_name='nearSurfRain';
sds_index = sd.nameToIndex(sd_id, datafield_name);
sds_id = sd.select(sd_id, sds_index);
[name, dimsizes, data_type, nattrs] = sd.getInfo(sds_id);
data = sd.readData(sds_id);

% Read units attribute.
units_index = sd.findAttr(sds_id, 'units');
units = sd.readAttr(sds_id, units_index);
sd.endAccess(sds_id);

% Read latitude.
geo_name='Latitude';
sds_index = sd.nameToIndex(sd_id, geo_name);
sds_id = sd.select(sd_id, sds_index);
[name, dimsizes, data_type, nattrs] = sd.getInfo(sds_id);
lat = sd.readData(sds_id);
sd.endAccess(sds_id);

% Read longitude.
geo_name='Longitude';
sds_index = sd.nameToIndex(sd_id, geo_name);
sds_id = sd.select(sd_id, sds_index);
[name, dimsizes, data_type, nattrs] = sd.getInfo(sds_id);
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);
lat=double(lat);

% Plot the data using surfacem and axesm.
latlim=[floor(min(min(lat))),ceil(max(max(lat)))];
lonlim=[floor(min(min(lon))),ceil(max(max(lon)))];
min_data=min(min(data));
max_data=max(max(data));

% Create a set of level ranges to be used in converting the data to a
% geolocated image that has a color assigned to each range.
levels = [0.0, 0.1, 1.0, 10.0 30.0];

% Create a color map.
cmap =jet(length(levels) + 1);

% Set the first entry of colormap as white, which will be used for
% fill value.
cmap(1, :,:) = [1 1 1];

% Convert the data to an geolcated image by setting a color for each level
% range.
Z = data;

% Clamp the min and max values to the level index.
Z(Z < levels(1)) = 1;
Z(Z > levels(end)) = length(levels);

% Assign Z as an indexed image with the index value corresponding to the
% level range.
for k = 1:length(levels) - 1
    Z(data >= levels(k) & data < levels(k+1)) = double(k) ;
end

% Set the fill region to the index corresponding the the color white (the
% lowest color value)
Z (data < 0.0) = 0;

% Load coastlines.
landareas = shaperead('landareas.shp', 'UseGeo', true);
coast.lat = [landareas.Lat];
coast.long = [landareas.Lon];

f = figure('Name', file_name, ...
    'Renderer', 'zbuffer', ...
    'Position', [0,0,800,600], ...
    'Visible', 'off', ...
    'PaperPositionMode', 'auto', ...
    'Colormap', jet(2048));

axesm('MapProjection','eqdcylin','Frame','on','Grid','on', ...
      'MeridianLabel','on','ParallelLabel','on')
tightmap
colormap(cmap)

% Use geoshow to plot the data as a geolocated indexed image.
geoshow(lat, lon, uint8(Z), cmap, 'd','image')
geoshow(coast.lat, coast.long, 'Color', 'k')

% Create a colorbar. The colorbar can be moved to the right side of the
% plot by setting 'Location' to 'vertical'.
caxis auto
clevels =  cellstr(num2str(levels'));
clevels = ['missing'; clevels]';

h = lcolorbar(clevels, 'Location', 'horizontal');
set(get(h, 'title'), 'string', units, ...
    'Interpreter', 'none', ...
    'FontSize', 16, 'FontWeight','bold');

% Put title.
tstring = {file_name; datafield_name; ''};
title(tstring, 'Interpreter', 'none', 'FontSize', 16,'FontWeight','bold');
saveas(f, [file_name '.m.png']);

exit;