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PADCAT

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PADCAT

by Jos (10584)

 

06 Feb 2009 (Updated 07 Oct 2011)

concatenate vectors with different lengths by padding with NaN (v1.2, oct 2011)

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Description

PADCAT - concatenate vectors with different lengths by padding with NaN
 
    M = PADCAT(V1, V2, V3, ..., VN) concatenates the vectors V1 through VN
    into one large matrix. All vectors should have the same orientation,
    that is, they are all row or column vectors. The vectors do not need to
    have the same lengths, and shorter vectors are padded with NaNs.
    The size of M is determined by the length of the longest vector. For
    row vectors, M will be a N-by-MaxL matrix and for column vectors, M
    will be a MaxL-by-N matrix, where MaxL is the length of the longest
    vector.
 
    Examples:
       a = 1:5 ; b = 1:3 ; c = [] ; d = 1:4 ;
       padcat(a,b,c,d) % row vectors
          % -> 1 2 3 4 5
          % 1 2 3 NaN NaN
          % NaN NaN NaN NaN NaN
          % 1 2 3 4 NaN
       CC = {d.' a.' c.' b.' d.'} ;
       padcat(CC{:}) % column vectors
          % 1 1 NaN 1 1
          % 2 2 NaN 2 2
          % 3 3 NaN 3 3
          % 4 4 NaN NaN 4
          % NaN 5 NaN NaN NaN
 
 
    [M, TF] = PADCAT(..) will also return a logical matrix TF with the same
    size as R having true values for those positions that originate from an
    input vector. This may be useful if any of the vectors contain NaNs.
 
    Example:
        a = 1:3 ; b = [] ; c = [1 NaN] ;
        [M,tf] = padcat(a,b,c)
        % find the original NaN
        [Vev,Pos] = find(tf & isnan(M))
        % -> Vec = 3 , Pos = 2

This second output can also be used to change the padding value into something else than NaN.

       [M, tf] = padcat(1:3,1,1:4)
       M(~tf) = 99 % change the padding value into 99
 
    Scalars will be concatenated into a single column vector.
 
    See also cat, reshape, strvcat, char, horzcat, vertcat, isempty
             nones, group2cell (Matlab File Exchange)

Acknowledgements

The author wishes to acknowledge the following in the creation of this submission:
padadd
This submission has inspired the following:
CATPAD

MATLAB release MATLAB 7.6 (R2008a)
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Comments and Ratings (5)
04 Jun 2009 Kent Conover

Works as advertised - many thanks!

01 Jul 2009 Laurence Johns  
10 Aug 2011 German

Nice utility, can it be modified to work with matrices and multidimensional arrays?

10 Aug 2011 German  
26 Oct 2011 Jonathan Sullivan

@German. You may want to check out the function catpad, it works on marticies and multidimensional arrrays.
http://www.mathworks.com/matlabcentral/fileexchange/33453

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Updates
07 Oct 2011

added help on how to change the padding value using the secondary output

Tag Activity for this File
Tag Applied By Date/Time
matrix Jos (10584) 06 Feb 2009 12:20:06
matrices Jos (10584) 06 Feb 2009 12:20:06
matrix manipulation Jos (10584) 06 Feb 2009 12:20:06
cat Jos (10584) 06 Feb 2009 12:20:06
concatenate Jos (10584) 06 Feb 2009 12:20:06
add Jos (10584) 06 Feb 2009 12:20:06
merge Jos (10584) 06 Feb 2009 12:20:06
fill Jos (10584) 06 Feb 2009 12:20:06
combine Jos (10584) 06 Feb 2009 12:20:06
lengths Jos (10584) 06 Feb 2009 12:20:06
different Jos (10584) 06 Feb 2009 12:20:06
nans Jos (10584) 06 Feb 2009 12:20:06
vectors Jos (10584) 06 Feb 2009 12:20:06
potw Shari Freedman 04 Sep 2009 14:27:03
pick of the week Jiro Doke 11 Feb 2011 20:12:12

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