how to change axis of a matix?
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Asliddin Komilov
am 13 Sep. 2019
Bearbeitet: Bruno Luong
am 15 Sep. 2019
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 Kommentare
Walter Roberson
am 14 Sep. 2019
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.
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Bruno Luong
am 15 Sep. 2019
Bearbeitet: Bruno Luong
am 15 Sep. 2019
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)');
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Walter Roberson
am 14 Sep. 2019
[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 Kommentare
Walter Roberson
am 15 Sep. 2019
(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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