target1.m

% How to create a simple target diagram
%
% A first example of how to create a simple target diagram given one set of
% reference observations and multiple model predictions for the quantity.
% The Matlab code is kept to a minimum.
%
% This example shows how to calculate the required statistics and produce
% the target diagram. All functions in the Skill Metrics Toolbox are
% designed to only work with one-dimensional arrays, e.g. time series of
% observations at a selected location. The one-dimensional data are read in
% as data structures via a mat file. The latter are stored in data
% structures in the format: ref.data, pred1.data, pred2.data, and
% pred3.data. The plot is written to a file in Portable Network Graphics
% (PNG) format.
%
% The reference data used in this example are cell concentrations of a
% phytoplankton collected from cruise surveys at selected locations and 
% time. The model predictions are from three different simulations that
% have been space-time interpolated to the location and time of the sample
% collection. Details on the contents of the data structures (once loaded)
% can be obtained by simply entering the data structure variable name at 
% the command prompt, e.g. for Matlab
% >> ref
% ref = 
%          data: [57x1 double]
%          date: {57x1 cell}
%         depth: [57x1 double]
%      latitude: [57x1 double]
%     longitude: [57x1 double]
%       station: [57x1 double]
%          time: {57x1 cell}
%         units: 'cell/L'
%          jday: [57x1 double]
%
% while for Octave
%
% >> fieldnames(ref)
% ans =
% {
%   [1,1] = data
%   [2,1] = date
%   [3,1] = depth
%   [4,1] = latitude
%   [5,1] = longitude
%   [6,1] = station
%   [7,1] = time
%   [8,1] = units
%   [9,1] = jday
% }

% Author: Peter A. Rochford
%         Symplectic, LLC
%         www.thesymplectic.com
%         prochford@thesymplectic.com

% Close any previously open graphics windows
close all;

% Set the figure properties (optional)
set(gcf,'units','inches','position',[0,10.0,12.0,10.0]);
set(gcf,'defaultLineLineWidth', 1.5); % linewidth for plots
set(gcf,'DefaultAxesFontSize',16); % font size of axes text

% Read in data from a mat file
load('target_data.mat');

% Calculate statistics for target diagram
target_stats1 = target_statistics(pred1,ref,'data');
target_stats2 = target_statistics(pred2,ref,'data');
target_stats3 = target_statistics(pred3,ref,'data');

% Store statistics in arrays
bias = [target_stats1.bias; target_stats2.bias; target_stats3.bias];
crmsd = [target_stats1.crmsd; target_stats2.crmsd; target_stats3.crmsd];
rmsd = [target_stats1.rmsd; target_stats2.rmsd; target_stats3.rmsd];

% Produce the target diagram
% Reference circles are plotted at the maximum range of the axes and at 0.7
% times the maximum range by default.
[hp, ht, axl] = target_diagram(bias,crmsd,rmsd);

% Write plot to file
writepng(gcf,'target1.png');