Selection of array elements with condition

Question

Katerina F 2024-7-28

0
链接

此问题的直接链接

https://ww2.mathworks.cn/matlabcentral/answers/2140926-selection-of-array-elements-with-condition

评论： Katerina F 2024-7-29

I have a 1×294 cell array. For simplicity I show here a shorter verion of this, 1x8

A={[-0.3368 -0.0329]} 
{ [-0.5666   -1.2306   -1.9879   -1.6091   -1.0889   -0.6703]}  {[-0.5950   -0.7264   -0.2151]} {[ -0.3346   -0.8525   -1.0663   -0.7172   -0.3690 ]}  {[-0.3587   -0.2960]}
{[-1.0327   -2.4401   -3.1295   -2.8144   -2.3720   -1.5680   -0.6808]} {[-0.3728   -1.0863   -1.0865   -0.6916   -0.4153   -0.0177]}   {[-0.3969   -1.2583   -1.9764   -2.7800   -2.4100   -1.6038   -0.4912]}

I want to write a code so that I select the array that contains the smallest number, in this case the smallest is -3.1295. So I would like that the answer is

[-1.0327 -2.4401 -3.1295 -2.8144 -2.3720 -1.5680 -0.6808]

Could you please help me with this? I tried this: A(cellfun(@(x) all(all(x==-0.3749)),A)) but it gives me an empty array. Thank you

0 个评论
显示 -2更早的评论隐藏 -2更早的评论

请先登录，再进行评论。

请先登录，再回答此问题。

Answer 1

dpb 2024-7-28

0
链接

此回答的直接链接

https://ww2.mathworks.cn/matlabcentral/answers/2140926-selection-of-array-elements-with-condition#answer_1491581

编辑：dpb 2024-7-28

在 MATLAB Online 中打开

A=[{[-0.3368 -0.0329]} ...
{ [-0.5666   -1.2306   -1.9879   -1.6091   -1.0889   -0.6703]}  {[-0.5950   -0.7264   -0.2151]} {[ -0.3346   -0.8525   -1.0663   -0.7172   -0.3690 ]}  {[-0.3587   -0.2960]} ...
{[-1.0327   -2.4401   -3.1295   -2.8144   -2.3720   -1.5680   -0.6808]} {[-0.3728   -1.0863   -1.0865   -0.6916   -0.4153   -0.0177]}   {[-0.3969   -1.2583   -1.9764   -2.7800   -2.4100   -1.6038   -0.4912]}];
whos A
  Name      Size            Bytes  Class    Attributes

  A         1x8              1136  cell               

Actually, it's 1x8 but who's counting??? :)

You were on the right track, but matching floating point with "==" is risky. Since you have a cell array with differently sized cells, rearranging into a regular 2D array and doing min by column doesn't work without a lot of additional effort.

So

minA=cellfun(@min,A)                    % go ahead and find the min of each
minA = 1x8
   -0.3368   -1.9879   -0.7264   -1.0663   -0.3587   -3.1295   -1.0865   -2.7800
<mw-icon class=""></mw-icon>
<mw-icon class=""></mw-icon>
[minA,ixA]=min(minA)                    % now find the min of the min's and return where it is
minA = -3.1295
ixA = 6
minC=A{ixA}                             % then the desired cell is the one at that location.
minC = 1x7
   -1.0327   -2.4401   -3.1295   -2.8144   -2.3720   -1.5680   -0.6808
<mw-icon class=""></mw-icon>
<mw-icon class=""></mw-icon>

NOTA BENE: If there might be a need for the other minima, you can "have your cake and eat it, too!"

[~,ixA]=min(minA)                    % now find the min of the min's and return ONLY where it is

The above would not overwrite the minA array, returning only the index of where the overall minimum is. (This must replace the above line, not follow it.)