contourc - plotting contour matrix
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I would like to find the contours, manipulate them, and then plot them.
This plots contours
x = 0:0.1:1; y = 0:0.1:1;
[X,Y] = meshgrid(x,y);
Z = sin(X).*cos(Y);
[con_mat, h] = contour(x, y, Z);
To get the contour information without plotting, can use contourc.
con_mat = contourc(x, y, Z);
However, there appears to be no built-in way to plot this "contour matrix".
Any thoughts?
John
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Darin
le 5 Juin 2012
Try this: it uses cplot, which you can find on Matlab central.
If you find something more elegant, please let us all know... it MUST be buried in the Matlab library function SOMEWHERE.
function[] = plot_contourmatrix(C);
% plot_countourmatrix - Plots a contour matrix c as returned from contour
%
% plot_contourmatrix(C)
% Rev History:
% 06-04-12 Created
figure(gcf);
holdstate = ishold;
hold on;
i = 1;
while i<=length(C)
lev = C(1,i);
cnt = C(2,i);
cplot(C(1,i+(1:cnt)),C(2,i+(1:cnt)),repmat(lev,1,cnt));
i = i+cnt+1;
end;
if ~holdstate
hold off;
end;
return
test code - execute as cell
figure(1);
[x,y] = meshgrid(-3:.1:3);
z = sinc(hypot(x,y));
[C,h] = contour(x,y,z);
axis equal
figure(2)
plot_contourmatrix(C);
axis equal
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Plus de réponses (1)
Liviu Ivanescu
le 18 Août 2018
Modifié(e) : Liviu Ivanescu
le 18 Août 2018
Here is a way to plot contourc data containing several contours of the same value.
cnt = contourc(matrix,[-2 -2]);
szc = size(cnt);
idz = 1;
while idz<szc(2)
izi = cnt(2,idz);
cnt(2,idz) = nan;
idz = idz+izi+1;
end
plot(cnt(1,:),cnt(2,:))
3 commentaires
Eduardo Vicente Wolf Trentini
le 2 Sep 2021
in the first line did you mean "cntr = contourc(matrix,[-2 -2]);"?
i think you forget the "r" in cntr
thanks
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