How can I make each cell array consistent in length?

In a cell array each element is 1Xlength. This length is not equal. I want to get the maximum length and then want to make each cell with same length by padding zeros in it.

Answer 1

[Jos (10584)]

A final attempt to answer this question :-)

C = {1:4 1:2 ; 1:5 1:6 ; 1 1:3} % a m-by-n cell array
N = cellfun(@numel, C) % old lengths of cell elements
M = 3 ; % new length should be multiple of M
newN = M * ceil(N / M) % new lengths of cell elements
padfun = @(k) [C{k} zeros(1, newN(k) - N(k))] ;
C2 = arrayfun(padfun, 1:numel(C) , 'un', 0) ; % apply padding to all elements of C
C2 = reshape(C2, size(C)) % reshape (if needed)

[Zara Khan]

Jos (10584):

Thank you so much. You are really great. You dont know how you have saved me. I was trying this from long . Thanks again.

But I apologise for mixing up two questions here. This was my another question where I asked how to divide a cell by32.

[Jos (10584)]

You're welcome, and thank you. I am glad we sorted it out :-)

[Zara Khan]

I am asking something more:

How can I put a condition here to check whether cell length is less than M or not . If it is less than M then only there will be padding otherwise not ?

[Jos (10584)]

After you calculated the new N you can use this:

tf = ~(N < M)    % true for the large cells
newN(tf) = N(tf) % reset to the old lengths

[Zara Khan]

Thank you . It works.

Answer 2

[tmarske]

%set up a dummy example
tst = {[1 1], [1 1 1 1 1], [1 1 1], [1]}
%get the maximum length
maxlen = max(cellfun(@length, tst))
%pad zeros
tstPadded = cellfun(@(x)([x zeros(1, maxlen - length(x))]), tst, 'UniformOutput', false)

[madhan ravi]

'prodofsize'

[Zara Khan]

tmarske:

I am working with mXn cell array. so I am getting this error "Size inputs must be scalar" while implementing your code.

[madhan ravi]

maxlen = max(cellfun('prodofsize', tst),[],[1 2]); % tst is m x n cell array
tstPadded = cellfun(@(x)([x zeros(1, maxlen - numel(x))]), tst, 'un', 0)

[Zara Khan]

Now I am getting this : Dimension argument must be a positive integer scalar within indexing range.

[madhan ravi]

>> tst = {[1 3 2]  7 6 ; 1:6 [11 2] 6} 
maxlen = max(cellfun('prodofsize', tst),[],[1 2]); % tst is m x n cell array
tstPadded = cellfun(@(x)([x zeros(1, maxlen - numel(x))]), tst, 'un', 0)

tst =

  2×3 cell array

    {1×3 double}    {[       7]}    {[6]}
    {1×6 double}    {1×2 double}    {[6]}


tstPadded =

  2×3 cell array

    {1×6 double}    {1×6 double}    {1×6 double}
    {1×6 double}    {1×6 double}    {1×6 double}

>> tstPadded{:}

ans =

     1     3     2     0     0     0

ans =

     1     2     3     4     5     6

ans =

     7     0     0     0     0     0

ans =

    11     2     0     0     0     0

ans =

     6     0     0     0     0     0

ans =

     6     0     0     0     0     0

>> 

[Zara Khan]

madhan ravi :

maxlen = max(cellfun('prodofsize', tst),[],[1 2]);

Error using max

Dimension argument must be a positive integer scalar within indexing range.

[madhan ravi]

M=reshape(cellfun('prodofsize',tst),1,[]);
maxlen=max(M);

[Zara Khan]

Its easy. Thanks for the response. But I am always facing the same problem when using cellfun

Error using cellfun

Input #2 expected to be a cell array, was double instead.

Error in prog_32 (line 66)

tstPadded = cellfun(@(x)([x zeros(1, maxlen - numel(x))]), M, 'un', 0)

Each cell consists of consequtives 0's and 1's. Whenever I am doing padding I am getting this error.

[madhan ravi]

I have no problem with the code , I have no idea why you get an error upload the code & data(as .mat file) that your trying.

[Zara Khan]

A=cell(numImages,8);
 B{k,j}=profile;
 A=B;
 
len = cellfun(@length, B);
len1 = 32 * ceil(len/32);
width_needed=cell(numImages,8);
width_needed=len1-len;

I am making each cell a multiple of 32. Now my task is to pad extra zero after the multiplication. And I want to keep them as cell format , no merging will be done. Here the profile is varying in length. Basically it consists of consequtives 0's and 1's. I am attaching few pictures here too.

[Jos (10584)]

Your code makes little sense. You overwrite A and width_needed.

I thought you needed the maximum of the lengths, so why don't you apply max?

[Zara Khan]

I dont want maxlength . I am making each cell a multiple of 32 . so i just want to add the extra places by zeros. maxlength will only find out maximum length among all.

[Jos (10584)]

Your question reads otherwise ... " I want to get the maximum length and then want to make each cell with same length by padding zeros in it.

Answer 3

[Jos (10584)]

If you make them the same length, you can also store them in a matrix. In that case, my PADCAT function is your friend :-)

C = {[1 2] ; 1 ; [1 2 3]}
[M, tf] = padcat(C{:}) % pads with NaNs 
M(~tf) = 0

PADCAT can be found on the File Exchange, for free:

https://uk.mathworks.com/matlabcentral/fileexchange/22909-padcat

(edited answer)

[Zara Khan]

what it will be if there is C{i,j} like thing ?

[Jos (10584)]

You mean a M-by-N cell array? I suggest you try it! :-)

C = {[1 2]  1 ; [1 2 3] [1 2]} % a 2-by-2 cell array with row vectors

[Zara Khan]

yes yes M×N cell array .

[Zara Khan]

This is shwoing wrong syntax : (M,tf) = padcat(C{:})

[Jos (10584)]

My mistake, should be square brackets of course ... (I edited my answer).

(assuming you also downloaded and installed the function)

[Zara Khan]

Jos (10584):

by using padcat I am getting a matrix where all coloumns are merged. That I dont want. I want to keep each cell as it is, just want want to add extra zeros. Like , first cell is 1X16, second is 1X31 and so on. I want to work on each indivisually. By adding extra zeros the first cell will be suppose 1X32 and so on. Remember I am dealing with mXn cell array.

Answer 4

[Jos (10584)]

C = {1:3 4 ; 5:9 10:12 ; 13:14 15} % a m-by-n cell array
N = cellfun(@numel, C) 
maxN = max(N(:))
padfun = @(v) [v zeros(1, maxN - numel(v))] ;
C2 = cellfun(padfun, C , 'un', 0)

[Zara Khan]

Each cell array consists of consequtives 0's and 1's. Padding with extra zero showing me error

size input must be scalar.

[Jos (10584)]

I do not get this error in the above code for a cell array like this

C = {[1 0 0 1], [0 1] ; [1 0 1 0], [0 0 1]}

You should give more details about the error and the input ...

[Zara Khan]

A=cell(numImages,8);
 B{k,j}=profile;
 A=B;
 
len = cellfun(@length, B);
len1 = 32 * ceil(len/32);
width_needed=cell(numImages,8);
width_needed=len1-len;

I am making each cell a multiple of 32. Now my task is to pad extra zero after the multiplication. And I want to keep them as cell format , no merging will be done. Here the profile is varying in length. Basically it consists of consequtives 0's and 1's. I am attaching few pictures here too.