Split or extract a part of the data in a cell

Starting from a cell called "data" sized 17x1, containing each one 1x1487040 double

i would be able to extract the first 1/4 of the content from the 9th to the 14th cells obtaining a matrix of double.

The problem arises because i usually have huge lengths for the double numbers in the cell, so that if i first use cell2mat (with the intention of splitting the array after) an out of memory error comes up.

It is possible to split a cell of double without cell2mat?

Answer 1

[Guillaume]

An alternative to Arnab's answer, using cellfun:

A = cell2mat(cellfun(@(v) v(1:numel(v)/4), data.data(9:14), 'UniformOutput', false))

Answer 2

[Arnab Sen]

Hi greta,

My understanding is that you would like to extract a part of cell from a cell array. You can directly access the cell of the cell array without converting the whole cell array to matrix. As an example, if you want to extract the first 1/4th content from 9th cell, you can do something link below:

 >> A=data{9}(:,1:length(data{9})/4);

You can use a for loop to extract from multiple cell. Something like

 >>for I=9:14
    A[I]=data{I}(:,1:length(data{I})/4);
  end

Regards,

Arnab

[Guillaume]

The gist of the idea is there, but I'd like to point out that:

A[I]

is not valid matlab syntax. At the very least, it should be

A(I, :)

And A should be predeclared before the loop.

Secondly, since the content of the cells are all vector, 2d indexing is not required so

data{I}(:,1:length(data{I})/4)

can be simplified to

data{I}(1:numel(data{I})/4) %and numel is a lot safer than length