how to change axis of a matix?
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my matrix is M(x,y,z) where:
x=1:90
y=1:3:120
z=1:40
and
c=y./z
and I need to convert M into N(x,c).
Any ideas?
6 个评论
Walter Roberson
2019-9-14
No, length of y and z are the same and y./z would have the same length.
Some of what you wrote does not seem to make sense until you start talking about grids of data, but then you have to ask about the sizes of the grids.
采纳的回答
Bruno Luong
2019-9-15
编辑:Bruno Luong
2019-9-15
load('testdata.mat');
Ufun = @(X,Y,Z) X;
Vfun = @(X,Y,Z) Y./(Z+200);
[X,Y,Z] = ndgrid(x,y,z);
U = Ufun(X,Y,Z);
V = Vfun(X,Y,Z);
U = U(:);
V = V(:);
[umin,umax] = bounds(U);
nu = 21;
u = linspace(umin,umax,nu);
[vmin,vmax] = bounds(V);
nv = 21;
v = linspace(vmin,vmax,nv);
[~,~,I] = histcounts(U,u);
[~,~,J] = histcounts(V,v);
N = accumarray([J I], M(:), [nu nv]-1, @mean, NaN);
midfun = @(x) 0.5*(x(1:end-1)+x(2:end));
u = midfun(u);
v = midfun(v);
surf(u,v,N);
xlabel('u (=x)');
ylabel('v (=y/(200+z)');
![mapping3D.png](https://www.mathworks.com/matlabcentral/answers/uploaded_files/238376/mapping3D.png)
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更多回答(1 个)
Walter Roberson
2019-9-14
[X, Y, Z]=ndgrid(1:90,1:3:120,1:40);
C = round(ceil(Y./Z));
N = accumarray([X(:), C(:)], M(:), [], @mean, nan);
surf(N, 'edgecolor', 'none')
xlabel('x')
ylabel('c')
Or possibly N.' instead of N
8 个评论
Walter Roberson
2019-9-15
(y-z)/y is 1-z/y and since z and y both include 0, you still have nan and infinities.
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