Extract data from a cell array/struct

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Richard Rees
Richard Rees 2019-7-30
评论： Richard Rees 2019-7-31
Good afternoon,
I have been having this probelm all day and I cannot fix it. I am trying to extract the the 3rd column (WaterCumulativeMass) from each of the cell arrays. The problem I am encountering is that the second cell array only contains the headers and no values (which is correct), so to keep consistancy with the other arrays I blank it. This has the effect of turning the cell array into a Struct which I then convert back into a cell array.
The code which works partially (shown) extracts the data from the third column of cell array but combines it into a single column vector where I would like it as columns like it would normally do in a matrix for anything involving a loop function with counter. If I were to use anything with a counter i.e. ABC(i) = array{i}.data(:,3) it states that the left and right sides are not equal or the dot function is not applicable to this etc.
I have tried extracting the data from the struct format aswell but this again will not work
Can someone help please?
% Partially successful cell array method
CC = mydata_EL;
CC{2} = [];
for i = 3:numel(CC); % Needs to start at 3rd column because of the blanks
ABC = CC{i}.data(:,3)% Does extract 3rd columns. Creates a single vector
%ABC(i) = CC{i}.data(:,3) # Does not work with the counter
end
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Richard Rees
Richard Rees 2019-7-31
编辑：Richard Rees 2019-7-31
Apollogies, I didn't realise I saved all the work space variables. Attached is the correct variable (CC.mat)
What I want to do is to extract the third column of the data field from each struct within the cell array and complile it into a matrix, whereby each extraction has its own column.
At the moment I can extract the data but it arranges it into a single vector i.e. 623x1 whereas I need in this instance 191x6
Eva-Maria Weiss
Eva-Maria Weiss 2019-7-31
Maybe reshape would help? lhttps://de.mathworks.com/help/matlab/ref/reshape.html
But since the number of values of both shapes you've written here is not equal, something else might going wrong...

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Guillaume
Guillaume 2019-7-31
What I want to do is to extract the third column of the data field from each struct within the cell array and complile it into a matrix, whereby each extraction has its own column [..] I need in this instance 191x6.
That's a lot clearer and easily done. Except for the 191 which I have no idea where it comes from since each data matrix is 636x3. The following creates a 636x6 matrix:
%concatenate the structure in each cell into a structure array:
data_struct = [mydata_EL{3:end}];
%concatenate the data field of each element of the array into a 3D matrix
data_mat = cat(3, data_struct.data);
%extract column 3 and reshape the Mx1xN array into a MxN array
data_col3 = squeeze(data_mat(:, 3, :));
The first two lines of code use what is known as expansion of cell arrays and structure arrays into comma-separated lists. For example,
[mydata_EL{2:end}]
is automatically expanded by matlab into
[my_data_EL{3}, my_data_EL{4}, .., my_data_EL{end}]
and
cat(3, data_struct.data)
automatically expanded into
cat(3, data_struct(1).data, data_struct(2).data, .., data_struct(end).data)

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