Contour plot shrinking about its origin

2020 10 10
2 个回答
更新时间：2020 10 10
8 次查看（30 天）

0 个投票

I have a contour plot. I need to shrink it about its origin. I have tried to shrink it as a polygon but it does not work. Could you please help me to overcome the problem? I want shrinking the contour plot about its origin.
I found the code below, but it is for contour plot rotation.
Note: I use matlab ver. 2008.
Any help will be much appreciated.
a = 37;
[x,y] = meshgrid(linspace(-4,4,30));
z = exp(-x.^2/15-y.^2);
contour(x,y,z)
xlim([-5 5])
ylim([-5 5])
axis equal
figure
[C,h] = contour(x,y,z);
rotate(get(h,'children'),[0 0 1],a)
xlim([-5 5])
ylim([-5 5])
axis equal
Many thanks
Israa

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Ameer Hamza
Ameer Hamza 2020-10-10
Can you explain what do you mean by shrinking the plot?
israa abdul jabbar
israa abdul jabbar 2020-10-10
编辑：israa abdul jabbar 2020-10-10
i want to make 2D transformation(scaling ) for the resulting contour plot. I want to reduce( shrink) the size of final contour plot about its origin .

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回答（2 个）

KSSV
KSSV 2020-10-10

0 个投票

You change the x,y limits and use the same z...
a = 37;
[x,y] = meshgrid(linspace(-4,4,30));
z = exp(-x.^2/15-y.^2);
figure(1)
contour(x,y,z)
xlim([-5 5])
ylim([-5 5])
axis equal
[x1,y1] = meshgrid(linspace(-1,1,30));
figure(2)
contour(x1,y1,z)
xlim([-1 1])
ylim([-1 1])
axis equal

7 个评论
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israa abdul jabbar
israa abdul jabbar 2020-10-10
Thank you so much, but i want to make 2D transformation(scaling ) for the resulting contour plot. I want to reduce( shrink) the size of final contour plot about its origin .
KSSV
KSSV 2020-10-10
Yes this can be done....read about Afine transformations. In there you have a transformation matrix to reduce the scale of your polygons.
israa abdul jabbar
israa abdul jabbar 2020-10-10
i did but it failed because contour polt or contour matrix is not a polygon. Thank you so much
KSSV
KSSV 2020-10-10
You have the points in hand...that's enough ..
israa abdul jabbar
israa abdul jabbar 2020-10-10
Below, my code for scaling contour plot, but it failed
center=polygonCentroid(u); % u is my contour plot
scalmatrix=createScaling(center,0.25,0.25); % making scaling matrix
u=transformPoint(u,scalmatrix); % scaling or shrinking process
[c,h] = contour(u,[2 2],'y','linewidth',3);
Star Strider
Star Strider 2020-10-10
What are these functions:
polygonCentroid
createScaling
transformPoint
and where did you get them?
I can find no references for them either in the MATLAB online documentation or in an Interweb search.
You are doing KSSV a definite disservice by not revealing sources for them or posting the code for them.
israa abdul jabbar
israa abdul jabbar 2020-10-10
iI take these functions from library called "geom2d", i got it from site of mathworks(file exchange). I added that library to my matlab(2008). my code is acceptable and implemented, but the results were wrong.
Note:
geom2d
version 1.25 (427 KB) by David Legland
Geometry library for matlab. Performs geometric computations on points, lines, circles, polygons...
https://github.com/mattools/matGeom

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israa abdul jabbar
israa abdul jabbar 2020-10-10

0 个投票

i want to make 2D transformation(scaling ) for the resulting contour plot. I want to reduce( shrink) the size of final contour plot about its origin .

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