Extracting data from figures

So i have a set of code that creates a bunch of figures for me. I would then like to extract the data from said figures.

Above are two examples of the figures.

Overlaid they look like this

These figures are origionally plotted using

function plotSpectrum(h,x,y,scale,colour)

% Deal with variable arguments

if nargin < 5 colour='black'; end
if nargin < 4 scale=1; end

% Plot

p=plot(h,x,real(y));
xlimits=[min(x),max(x)];
ylimits=[min(real(y)),max(real(y))/scale];

% Format

set(p,'color',colour,'LineWidth',1);
set(h,'xlim',xlimits,'ylim',ylimits,'xdir','reverse');

and overlaid using

fh1 = open('1hydrogen.fig');
fh2 = open('2hydrogen.fig');
ax1 = get(fh1, 'Children');
ax2 = get(fh2, 'Children');
ax2p = get(ax2(1),'Children');
copyobj(ax2p, ax1(1));

So i then try to extract the data

data = pwd;
dinfo = dir(fullfile(data,'*gen.fig'));
fignames = {dinfo.name};
numfig = length(fignames);
y = cell(numfig, 1);
z = cell(numfig, 1);
inter_y = cell(numfig, 1);
inter_z = cell(numfig, 1);

for K = 1 : numfig
  figfile = fignames{K};
  try
    fig = openfig(figfile,'invisible');
    ax = get(fig, 'CurrentAxes');
    if ~isempty(ax)
      hline = get(ax, 'Children');
        y{K} = get(hline,'XData');
        z{K} = get(hline,'YData');
        
        inter_y{K} = y{K}(1,5:124);
        inter_z{K} = abs(z{K}(1,5:124));
    end
    close(fig);
  end
end

Then if i use something to test this extraction like.

test = inter_z{1,1};
test2 = inter_z{2,1};
testx = 1:120
plot (testx,test)
hold on
plot (testx,test2)

I get

Which is clearly different to the other overlay example. I am trying to get it so that my extracted data looks the same when plotted as the origional as this is needed for later coding.

Any help would be appreciated.

Answer 1

[Cris LaPierre]

You have the code that creates the figures, but you want to extract the data from the figure? Why? Don't you already have the data captured in the variables used to create the plot?

Still, you can do the following. The figure contains a child, which is the axes. You axes contain 2 children, the two lines. Each line has an XData and YData property. You can acces the data from the figure that way.

% Create a figure
plot(0:0.1:1);

% Extract X and Y data
fh = gcf;
ax = fh.Children(1);
ln1 = ax.Children(1);
X = ln1.XData

X = 1×11

1 2 3 4 5 6 7 8 9 10 11

Y = ln1.YData

Y = 1×11

0 0.1000 0.2000 0.3000 0.4000 0.5000 0.6000 0.7000 0.8000 0.9000 1.0000