contourc - plotting contour matrix
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John Mahoney
am 1 Jun. 2012
Kommentiert: Liviu Ivanescu
am 2 Sep. 2021
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
am 5 Jun. 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
2 Kommentare
Weitere Antworten (1)
Liviu Ivanescu
am 18 Aug. 2018
Bearbeitet: Liviu Ivanescu
am 18 Aug. 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 Kommentare
Eduardo Vicente Wolf Trentini
am 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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