split matrix into multiple matrices with variable number of rows according to value of a column

Hi

I have a large mx2 matrix that i want to split into multpile mx2 matrices according the value of column 1. so lets say for values of [20,100[ of column 1 i want to create a seperate mx2 matrix. then for [100,500[ another one and so one. The numner of rows can change for the large matrix but i always want to create 5 smaller matrices according to the value of the first column. So the smaller matrices wil also have a different number of rows. I added an example of a matrix in excell. Can someone help me with this problem?

thanks in advance

[darova]

How do you want to define 5 matrices? How should it be divided?

[dpb]

See

doc mat2cell

I'd recommend against creating multiple separately-named arrays; use the resulting cell array indices to select the desired pieces.

[Sören Gevaert]

Thanks for the reply. So lets say this is my large matrix. I want to create 5 new matrices based on the value of column 1. De number of rows can vary for every smaller matrix. so matrix 1 for freq(Hz): [20,50[, matrix 2 for freq(Hz): [54,74[ and so on.

I hope this figure explains my problem?

Thanks in advance

[Stephen23]

"I hope this figure explains my problem? "

Not really. Your sample file has values in the first column that range from 20 to 2001: you have not explained the general rule/s for how you want to split up those values (or any other values that you might have) into five groups.

[Sören Gevaert]

Thanks for the answer. The figure above is just an example. so first i need to set the limits. So lets say for column1 the values from 20 to 100 wil be the first matrix. then the values from 100 to 500 will be the second matrix. But for each matrix i need to have the corresponding values of column2 like my figure above. So at the end the large matrix will be split into 5 matrixes according to the values of column1.

Thanks in advance!

Answer 1

[darova]

Here is how i see the solution

S = importdata('Bspectrumgloei.xlsx');
A = S.data;
ind = [ 20 54 78 98 132 ];
A1 = cell(5,1);

for i = 1:length(ind)-1
    ix1 = find(A(:,1)==ind(i),   1,'first');
    ix2 = find(A(:,1)==ind(i+1), 1,'first');
    A1{i} = A(ix1:ix2-1,:);
end
A1{end} = A(ix2+1:end,:);

[Sören Gevaert]

Thanks for the answer. unfortunately its not quite the answer what i need as i get ix1 = 17, and ix2 = 24. So it just gives me the number of rows between 2 limits. also i dont quite understand the code. What i want is to make 5 new matrices from the large matrix so i get 5 new matrices with 2 colums. the number of rows depends on the limits from column 1 (freq). The values of the limits wil always be fixed but the number of rows can vary.

thanks in advance

[darova]

I think you need mat2cell as dpd suggested earlier

Just divide your matrix into 5 equal