Adding column to cell array

Question

I have a cell that has the following data:

Tom     Student
Jim     Faculty     
Clare   Student

What I want to do is add in another column in front to be a serial number.

1   Tom     Student
2   Jim     Faculty     
3   Clare   Student

Could someone give some advise please?

[{1;2;3}, data] where data is the cell array of strings. — Evgeni Sergeev
– Evgeni Sergeev, Commented Sep 6, 2014 at 7:23

chappjc · Accepted Answer · 2013-10-30 07:18:40Z

11

You have A defined as:

>> A={'Tom', 'Student'; 'Jim', 'Faculty'; 'Clare', 'Student'}

A = 

    'Tom'      'Student'
    'Jim'      'Faculty'
    'Clare'    'Student'

To add a column:

>> newCellCol = strsplit(num2str(1:size(A,1)))'

newCellCol = 

    '1'
    '2'
    '3'

>> A = [newCellCol A]

A = 

    '1'    'Tom'      'Student'
    '2'    'Jim'      'Faculty'
    '3'    'Clare'    'Student'

>>

For numeric arrays in the first column instead:

>> newCellCol = mat2cell(1:size(A,1),1,ones(1,size(A,1)))';
>> A = [newCellCol A]

A = 

    [1]    'Tom'      'Student'
    [2]    'Jim'      'Faculty'
    [3]    'Clare'    'Student'

You can also use num2cell(1:size(A,1))' in place of mat2cell above, as noted by Dan.

edited Oct 30, 2013 at 7:18

answered Oct 30, 2013 at 5:20

chappjc

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Comments

Marcin · Accepted Answer · 2013-10-30 05:18:39Z

1

Not sure exactly how your cell array is organized, but if like below, you can do as follows:

A={{'Tom', 'Student'}, ...
    {'Jim', 'Faculty'}, ...
    {'Clare', 'Student'}};


sizeA = size(A,2);

for i = 1:sizeA
    A{i} = [i, A{i}]
end

% alternatively, instead of a for loop, you can use cellfun
% A = cellfun(@(x, i)[i x], A, num2cell(1:size(A, 2)), 'UniformOutput',0)

A{1}
A{2}
A{3}

ans = 

    [1]    'Tom'    'Student'


ans = 

    [2]    'Jim'    'Faculty'


ans = 

    [3]    'Clare'    'Student'

edited Oct 30, 2013 at 5:18

answered Oct 30, 2013 at 5:10

Marcin

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3 Comments

Dan Over a year ago

Why not just a=num2cell(1:3)'; [a,A];?

Marcin Over a year ago

@Dan Better, but it gives an error "Dimensions of matrices being concatenated are not consistent." I'm sure it could be fixed quickly, but I have to go now. No time to check. Thx.

Dan Over a year ago

I think that's because you have made A a cell array of cell arrays instead of a cell matrix like in the OP.

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