Try this:
F = openfig('Bild_versch.fig');
Lines = findobj(F, 'Type','Line');
X = Lines.XData;
Y = Lines.YData;
LM = X > 0; % Logical Mask: Only Positive ‘X’ Values
figure
plot(X(LM), Y(LM))
grid
xlim([0 0.005]) % Optional
Note that since 0 has no sign, it is not considered to be either positive or negative. To include it, change the ‘LM’ assignment to:
LM = X >= 0; % Logical Mask: Only Non-Negative ‘X’ Values
