将一维阵列重塑为网格网格格式

Question

我有数据x，y，z和v，组织成列向量。类似的数据可以通过以下代码获得：

N = 5;
[xf,yf,zf,vf] = flow(N);
ux = unique(xf);
uy = unique(yf);
uz = unique(zf);
x = nan(numel(xf),1);
y = nan(numel(yf),1);
z = nan(numel(zf),1);
v = nan(numel(vf),1);
iCount = 1;
for iX = 1:numel(ux)
for iY = 1:numel(uy)
for iZ = 1:numel(uz)
x(iCount) = ux(iX);
y(iCount) = uy(iY);
z(iCount) = uz(iZ);
v(iCount) = vf((xf == x(iCount))&(yf == y(iCount))&(zf == z(iCount)));
iCount = iCount+1;
end
end
end

我无法更改数据生成的方式，因此我需要对其进行重塑，以便以后使用isosurface()和稍后griddedInterpolant()。原始数据的大小相当大，我想避免循环。reshape()功能的简单用法：

X = reshape(x,[N,2*N,N]);
Y = reshape(y,[N,2*N,N]);
Z = reshape(z,[N,2*N,N]);
V = reshape(v,[N,2*N,N]);
isosurface(X,Y,Z,V,-3)

告诉我，那Input grid is not a valid MESHGRID.

你能帮我以适当的方式重塑数据吗？

Answer 1

数组中项目的顺序与来自meshgrid的列主顺序不匹配。您几乎完成了，但您需要用不同的形状重塑您的 1D 数组，然后将结果排列回您需要的实际形状：

N = 5;
[xf,yf,zf,vf] = flow(N);
ux = unique(xf);
uy = unique(yf);
uz = unique(zf);
x = nan(numel(xf),1);
y = nan(numel(yf),1);
z = nan(numel(zf),1);
v = nan(numel(vf),1);
iCount = 1;
for iX = 1:numel(ux)
for iY = 1:numel(uy)
for iZ = 1:numel(uz)
x(iCount) = ux(iX);
y(iCount) = uy(iY);
z(iCount) = uz(iZ);
v(iCount) = vf((xf == x(iCount))&(yf == y(iCount))&(zf == z(iCount)));
iCount = iCount+1;
end
end
end
% new stuff starts here
X = permute(reshape(x,[N,N,2*N]),[2,3,1]);
Y = permute(reshape(y,[N,N,2*N]),[2,3,1]);
Z = permute(reshape(z,[N,N,2*N]),[2,3,1]);
V = permute(reshape(v,[N,N,2*N]),[2,3,1]);
% check equivalence
isequal(X,xf)
isequal(Y,yf)
isequal(Z,zf)
isequal(V,vf)

上面表明输入数组被复制(我们得到四个逻辑1(。

请注意，您的测试用例应该更加不对称，因为现在一些输入数组是彼此的转置，并且三个维度中的两个具有相同的大小。如果您的测试尺寸不对称，即[N,M,K]，找出可能的歧义要容易得多，因为在这种情况下所有维度都是不等价的：

N = 2; M = 3; K = 4;
[xf,yf,zf] = meshgrid(1:N,1:M,1:K);
vf = flow(xf,yf,zf);
ux = unique(xf);
uy = unique(yf);
uz = unique(zf);
x = nan(numel(xf),1);
y = nan(numel(yf),1);
z = nan(numel(zf),1);
v = nan(numel(vf),1);
iCount = 1;
for iX = 1:numel(ux)
for iY = 1:numel(uy)
for iZ = 1:numel(uz)
x(iCount) = ux(iX);
y(iCount) = uy(iY);
z(iCount) = uz(iZ);
v(iCount) = vf((xf == x(iCount))&(yf == y(iCount))&(zf == z(iCount)));
iCount = iCount+1;
end
end
end
X = permute(reshape(x,[K,M,N]),[2,3,1]);
Y = permute(reshape(y,[K,M,N]),[2,3,1]);
Z = permute(reshape(z,[K,M,N]),[2,3,1]);
V = permute(reshape(v,[K,M,N]),[2,3,1]);
% check equivalence
isequal(X,xf)
isequal(Y,yf)
isequal(Z,zf)
isequal(V,vf)