Interpolate line data to grid matlab

How can I find the points (red circles) which an arbitrary line (blue line) intersects in a grid?

Answer 1

[Star Strider]

Use the interp1 function —

x = [0.0 5.0];
y = [1.0 3.8];

figure
plot(x, y)
grid
hold on
Ax = gca;
xtix = Ax.XTick                                         % X-Tick Grid Line Locations

xtix = 1x6

0 1 2 3 4 5

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yvals = interp1(x, y, xtix)                             % Interpolate

yvals = 1x6

1.0000 1.5600 2.1200 2.6800 3.2400 3.8000

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scatter(xtix, yvals)                                    % Plot Results
hold off
ylim([0 5])

Also, if you do not have the information that created the plot, you can get it from the plot —

GetLines = findobj(Ax, 'Type','Line');
xv = GetLines.XData

xv = 1x2

0 5

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yv = GetLines.YData

yv = 1x2

1.0000 3.8000

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yvals = interp1(xv, yv, xtix)

yvals = 1x6

1.0000 1.5600 2.1200 2.6800 3.2400 3.8000

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EDIT — (3 Apr 2024 at 21:47)

Added the last part with ‘GetLines’ and following code.

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