How to Extract Data from a MATLAB Figure (.fig)

Step 1: Extract Line Plot Coordinates (X, Y, Z)

If you lost your original source dataset but saved the MATLAB plot figure (.fig), follow this exact script to extract all data points:

% Step 1: Open figure invisibly in memory
figHandle = openfig('sample_plot.fig', 'reuse', 'invisible');

% Step 2: Find all line objects in current axes
lineHandles = findobj(figHandle, 'Type', 'line');

% Step 3: Extract X, Y, and Z data arrays
xData = get(lineHandles(1), 'XData');
yData = get(lineHandles(1), 'YData');

% Step 4: Close figure handle
close(figHandle);

% Output dataset dimensions
fprintf('Extracted %d data points successfully.\n', length(xData));

Step 2: Extract Data from Multi-Subplot Figures

When a .fig file contains multiple subplots, iterate through every axis handle to extract distinct datasets:

fig = openfig('multi_subplot.fig', 'reuse', 'invisible');

% Retrieve all axis handles
allAxes = findobj(fig, 'Type', 'axes');

extractedData = struct();

for k = 1:length(allAxes)
    currentLine = findobj(allAxes(k), 'Type', 'line');
    if ~isempty(currentLine)
        extractedData(k).X = get(currentLine(1), 'XData');
        extractedData(k).Y = get(currentLine(1), 'YData');
        fprintf('Subplot %d: Extracted %d points.\n', k, length(extractedData(k).X));
    end
end

close(fig);

Step 3: Extract Matrix Data from Images, Heatmaps & Contour Plots

To extract numerical matrix data from heatmaps, images, or contour figures, extract the CData property:

fig = openfig('heatmap_plot.fig', 'reuse', 'invisible');

% Locate image or surface handle
imgObj = findobj(fig, 'Type', 'image');
if isempty(imgObj)
    imgObj = findobj(fig, 'Type', 'surface');
end

% Extract raw matrix array
matrixData = get(imgObj(1), 'CData');
close(fig);

disp('Extracted Matrix Size:');
disp(size(matrixData));

Step 4: Export Extracted MATLAB Data (CSV, Excel, MAT-file)

Save your extracted arrays to `.csv`, `.xlsx`, or `.mat` formats for downstream work:

% Option A: Export to CSV / Excel
dataTable = table(xData', yData', 'VariableNames', {'X_Values', 'Y_Values'});
writetable(dataTable, 'ExtractedFigureData.csv');

% Option B: Save directly to MAT-file
save('ExtractedDataset.mat', 'xData', 'yData', 'matrixData');