How to split data matrix conditionally?

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Andi
Andi on 14 Apr 2022
Commented: Andi on 14 Apr 2022
I have a data matrix of 59 columns and variabale number of rows, Required to extract a new matrix such that it include only those values that are in a specific bound.
As a result, we left with variable number of observations in each coloumn. How can i get new matrix, in such a condition:
An examplry random data set with my approach as below, but did not get required results.
p = rand(10, 10)
for i=1:10
q = p((p(:,ii) > .2) & (p(:,ii) < .4) , :)
end

Accepted Answer

Chunru
Chunru on 14 Apr 2022
Edited: Chunru on 14 Apr 2022
You will not get an matrix for the output since the number of entries satisfying the condition for each column will be different.
Your output can be combined as a cell array instead.
n = 50;
p = rand(n, n);
for i=1:n
pi = p(:, i);
q{i} = pi(pi > .2 & pi < .4);
end
q
q = 1×50 cell array
{13×1 double} {13×1 double} {9×1 double} {12×1 double} {11×1 double} {6×1 double} {9×1 double} {14×1 double} {8×1 double} {13×1 double} {10×1 double} {9×1 double} {9×1 double} {10×1 double} {8×1 double} {10×1 double} {17×1 double} {10×1 double} {14×1 double} {11×1 double} {9×1 double} {7×1 double} {5×1 double} {9×1 double} {8×1 double} {12×1 double} {12×1 double} {14×1 double} {9×1 double} {7×1 double} {5×1 double} {13×1 double} {9×1 double} {10×1 double} {10×1 double} {15×1 double} {9×1 double} {13×1 double} {12×1 double} {9×1 double} {11×1 double} {13×1 double} {10×1 double} {6×1 double} {12×1 double} {11×1 double} {12×1 double} {10×1 double} {11×1 double} {10×1 double}
%% counting base on q (actually you can do that on p instead)
count = cellfun(@numel, q)
count = 1×50
13 13 9 12 11 6 9 14 8 13 10 9 9 10 8 10 17 10 14 11 9 7 5 9 8 12 12 14 9 7
% number of cells with >=10 elements
nc = sum(count>=10)
nc = 31
  12 Comments
Andi
Andi on 14 Apr 2022
we did mistake here that why we get NaN
e{ii, kk}=a(a(:, ii)>L_lim(:,kk) & a(:,ii)<U_lim(:, kk), ii);
Thank you for help.

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