MatLab相对于第一列转换矩阵 [英] MatLab to convert a matrix with respect to 1st col

问题描述

这个问题是通过第一列索引将不同行中的值分组

如果

      A = [2 3 234 ; 2 44 99999; 2 99999 99999; 3 123 99; 3 1232 45; 5 99999 57]

1st column |  2nd column | 3rd column
--------------------------------------
2             3          234
2             44         99999
2             99999      99999
3             123        99
3             1232       45
5             99999        57

我想做

1st col |  2nd col | 3rd col | 4th col | 5th col | 6th col| 7th col
--------------------------------------------------------------------
2         3        234       44       
3         123      99        1232      45
5         57

也就是说，对于A的第1个列中的每个数字，我想输入除"99999"以外的数字

That is, for each numbers in the 1st col of A, I want to put numbers EXCEPT "99999"

如果我们忽略"99999除外"部分，则可以将代码编码为按第一列索引将不同行中的组值分组

If we disregard the "except 99999" part, we can code as Group values in different rows by their first-column index

[U, ix, iu] = unique(A(:,1));
vals = reshape(A(:, 2:end).', [], 1);                    %'// Columnize values
subs = reshape(iu(:, ones(size(A, 2) - 1, 1)).', [], 1); %'// Replicate indices
r = accumarray(subs, vals, [], @(x){x'});

但是显然，此代码不会忽略99999.

But obviously this code won't ignore 99999.

我想有两种方法

1. first make r, and then remove 99999
2. remove 99999 first, and then make r

无论如何，我只想快一点.

Whichever, I just want faster one.

提前谢谢！

推荐答案

我认为选项1更好，即先设为r，然后删除99999 .有了r，您可以按以下方式删除99999:

I think options 1 is better, i.e. first make r, and then remove 99999. Having r, u can remove 99999 as follows:

r2 = {}; % new cell array without 99999

for i = 1:numel(r)    
    rCell = r{i};
    whereIs9999 = rCell == 99999; 
    rCell(whereIs9999) = []; % remove 99999
    r2{i} = rCell;
end

或更花哨的方式:

r2= cellfun(@(c) {c(c~=99999)}, r);

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