splitapply with multiple output variables

Question

Charlotte Mock 2023-2-23

1
链接

此问题的直接链接

https://ww2.mathworks.cn/matlabcentral/answers/1917605-splitapply-with-multiple-output-variables

评论： Matt J 2023-2-23

Hi,

I would like to use splitapply in combination with the function mink on a column of a cell array. My code below gives me the correct number of minimum values for each of my groups, however, it does not give the indices for these values.

This is my code:

quantGroups = findgroups([locAwayFromMean{:,12}]); % grouping info as vector
funcMink = @(x) {mink(x,10)}; % anonymous fct to get 10 lowest values of x
valMink = splitapply(funcMink,cell2mat(locAwayFromMean(:,11)),quantGroups'); % apply fct to each group 

I have a 258x12 cell (locAwayFromMean) where column 12 gives information about grouping. I want to get 10 minimum values (stored in column 11) for each group and also the indices of these data points.

The mink function [B,I] = mink(___) does allow to extract the indices but I am not sure how to implement this into my code above.

If I use this line

[valMink, Idx] = splitapply(funcMink,cell2mat(locAwayFromMean(:,11)),quantGroups');

it produces the following error message:

Error using splitapply

Applying the function '@(x){mink(x,10)}' to the 1st group of data generated the following error:

Insufficient number of outputs from right hand side of equal sign to satisfy assignment.

Thanks in advance!

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

Matt J 2023-2-23

0
链接

此回答的直接链接

https://ww2.mathworks.cn/matlabcentral/answers/1917605-splitapply-with-multiple-output-variables#answer_1178320

编辑：Matt J 2023-2-23

在 MATLAB Online 中打开

quantGroups = findgroups([locAwayFromMean{:,12}]); % grouping info as vector
X=cell2mat(locAwayFromMean(:,11));
I=1:numel(X);
[valMink,indexMink] = splitapply(@funcMink, X(:), I(:), quantGroups(:)); % apply fct to each group 
function [minval,minIndex]=funcMink(X,I)
   [minval{1},j]=mink(X,10);
   minIndex={I(j)};
end

6 个评论
显示 4更早的评论隐藏 4更早的评论

Matt J 2023-2-23

在 MATLAB Online 中打开

Here is a demo:

locAwayFromMean=reshape(1:30*12,30,12);
locAwayFromMean(:,12)=repelem([1;2],15)
locAwayFromMean = 30×12
     1    31    61    91   121   151   181   211   241   271   301     1
     2    32    62    92   122   152   182   212   242   272   302     1
     3    33    63    93   123   153   183   213   243   273   303     1
     4    34    64    94   124   154   184   214   244   274   304     1
     5    35    65    95   125   155   185   215   245   275   305     1
     6    36    66    96   126   156   186   216   246   276   306     1
     7    37    67    97   127   157   187   217   247   277   307     1
     8    38    68    98   128   158   188   218   248   278   308     1
     9    39    69    99   129   159   189   219   249   279   309     1
    10    40    70   100   130   160   190   220   250   280   310     1
locAwayFromMean=num2cell(locAwayFromMean);
quantGroups = findgroups([locAwayFromMean{:,12}]); % grouping info as vector
X=cell2mat(locAwayFromMean(:,11));
I=1:numel(X);
[valMink,indexMink] = splitapply(@funcMink, X(:), I(:), quantGroups(:)); % apply fct to each group 
valMink{:}
ans = 10×1
   301
   302
   303
   304
   305
   306
   307
   308
   309
   310
ans = 10×1
   316
   317
   318
   319
   320
   321
   322
   323
   324
   325
indexMink{:}
ans = 10×1
     1
     2
     3
     4
     5
     6
     7
     8
     9
    10
ans = 10×1
    16
    17
    18
    19
    20
    21
    22
    23
    24
    25
function [minval,minIndex]=funcMink(X,I)
   [minval{1},j]=mink(X,10);
   minIndex={I(j)};
end

Charlotte Mock 2023-2-23

Thank you, Matt!

P.S.: It appears that if I run your demo as an entire script everything works fine. However, if I run it line by line it produces the same error message "undefined function...". Not sure what that is about...

Matt J 2023-2-23

Well, you can't run it line by line, because one of those lines calls a function (funcMink) that Matlab needs to be able to find. You have to make the function visible to Matlab first.

请先登录，再进行评论。