Add new elements into cell array inside a loop

Question

Michail Isaakidis 2019-1-14

0
链接

此问题的直接链接

https://ww2.mathworks.cn/matlabcentral/answers/439692-add-new-elements-into-cell-array-inside-a-loop

编辑： Stephen23 2019-1-14

Hello all!

I I have a set of 10000 values and according to the thresholds I am setting I want to seperate them into individual matrices that would be inside the cell. The matrices elements are distributed trough a loop as above:

 for i=1:1:length(TestData)
     for k=1:1:4
        if TestData(i,3)>=low(k,1) && TestData(i,3)<=high(k,1)
            CreatedCell{k}=TestData(i,:);
        end
    end
 end

So how could I store my data into the cell and create multiple matrices? With the way I am doing it now it stores only the last value but I need to store the whole matrices.

3 个评论
显示 1更早的评论隐藏 1更早的评论

Guillaume 2019-1-14

The first issue is that you're using length as a synonym for the number of rows on something that is clearly a matrix. length returns the number of rows or columns, whichever is greater, so you're taking a risk. It would be much better to use size(TestData, 1) to ensure you always get the number of rows.

What does it doesn't work mean? If you get an error, what is the full text of the error? If you don't get the result you expect, then what exactly did you expect and what did you get instead.

Michail Isaakidis 2019-1-14

Thats exactly what happens. Leaves the data from last iteration, but I need to store all the values. On my code is not named as Cell, just for the understanding here I named it like that.

请先登录，再进行评论。

请先登录，再回答此问题。

Answer 1

Stephen23 2019-1-14

0
链接

此回答的直接链接

https://ww2.mathworks.cn/matlabcentral/answers/439692-add-new-elements-into-cell-array-inside-a-loop#answer_356348

编辑：Stephen23 2019-1-14

This will store the data each iteration of both loops (but I did not change the logical conditions):

N = size(TestData,1); % much better than length
C = cell(N,4);
for ii = 1:N
     for jj = 1:4
        if TestData(ii,3)>=low(jj,1) && TestData(ii,3)<=high(jj,1)
            C{ii,jj} = TestData(ii,:);
        end
    end
end

Note that this can create copies of the same data in the cell array. This may or may not be what you expect (it is not clear from your question).

4 个评论
显示 2更早的评论隐藏 2更早的评论

Michail Isaakidis 2019-1-14

Ok i.e you have a 10000 samples with values from 1 to 100 and you want to seperate them to different matrices according their values :

Matrix1 10-19

Matrix2 20-30

etc

You can use these as inputs to my code:

TestData = ceil(100*rand(10000,1));

low= [10; 20; 40; 60];

high=[20; 40; 60; 80];

Stephen23 2019-1-14

编辑：Stephen23 2019-1-14

>> TD = randi([1,100],10000,1); % fake data: random integers [1,100].
>> B = 1:20:101;                % bin lower edges.
>> [bin,idx] = histc(TD,B);     % match data to bins: B(n)<=data<B(n+1).
>> C = accumarray(idx,TD,[],@(v){v}); % split data according to matched bins.

请先登录，再进行评论。