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将一维数组重塑为网格网格格式

reshape matlab arrays

zlon · 技术社区 · 6 年前

我有数据 x 我是说, y , z 和 v ,按列向量组织。可通过以下代码获得类似数据:

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

我无法改变数据生成的方式,因此需要对其进行重新调整,以便以后使用 isosurface() 和 griddedInterpolant() 稍后。原始数据的大小相当大,我希望避免循环。简单使用 reshape() 功能:

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)

给我看,那个 Input grid is not a valid MESHGRID.

你能帮助我以适当的方式重塑数据吗?

1 回复 | 直到 6 年前

Andras Deak -- Ð¡Ð»Ð°Ð²Ð° Ð£ÐºÑÐ°ÑÐ½Ñ 6 年前

数组中项目的顺序与来自的列主顺序不匹配 meshgrid .你已经差不多完成了,但是你需要用不同的形状重塑你的1D数组,然后将结果转换回你需要的实际形状:

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)

上面的内容表明输入数组被复制(我们得到了四个逻辑数组 1 S)。

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,并且三维中的两个具有相同的大小。如果你的测试尺寸不对称,即 [N,M,K] ,更容易找出可能的歧义,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)