Accessing multiple columns in cell array

Hi,

I need to calculate the mean of 5 measurements. The 5 measurements are presented in a 5*1 cell array. The variable is called Data.

Thus, I need the mean of:

Data{1, 1}(:,end)

Data{2, 1}(:,end)

Data{3, 1}(:,end)

Data{4, 1}(:,end)

Data{5, 1}(:,end)

How do I acces all 5 columns at once?

Thanks in advance.

-Lasse

Answer 1

[KSSV]

A = cat(3,Data{:}) ;            % convert cell array to 3D matrix
m = cell2mat(mean(A(:,end,:)))    %  mean of last column 

Answer 2

[Scott MacKenzie]

You need to retrieve the elements in their underlying data type (hence the use of braces) and concatenate the values using brackets:

mean([Data{:,1}])

If indeed thare are only 5 values (measurements), then you don't need ",1". Just use

mean([Data{:}])

Have a look here for a summary of the ways to access data in a cell array. Good luck.

Answer 3

[Stephen23]

Fake data:

Data = arrayfun(@(n)randi(9,2,3),1:5,'uni',0).'; % fake data
Data{:}

ans = 2×3

2 5 6 6 5 4

ans = 2×3

9 3 5 1 3 5

ans = 2×3

3 1 9 8 5 2

ans = 2×3

5 6 6 2 4 1

ans = 2×3

2 7 2 1 7 5

Method one:

M = mean(cat(3,Data{:}),3);
M = M(:,end)

M = 2×1

5.6000 3.4000

Method two:

M = mean(cell2mat(reshape(Data,1,1,[])),3);
M = M(:,end)

M = 2×1

5.6000 3.4000

Method three:

M = mean(cell2mat(cellfun(@(m)m(:,end),Data.','uni',0)),2)

M = 2×1

5.6000 3.4000

Method four:

M = mean(cell2mat(arrayfun(@(n)Data{n}(:,end),1:numel(Data),'uni',0)),2)

M = 2×1

5.6000 3.4000