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REPLICATE

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REPLICATE

by

Mark Ruzon

 

04 Dec 2008 (Updated )

Create a larger array by expanding each element of an array into a subarray.

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Description

REPLICATE is a companion to REPMAT, but instead of tiling a larger array with the input array, REPLICATE does the equivalent of calling REPMAT on each individual element and then tile the results together. It is faster than looping over each element. It supports 2D and 3D arrays.

Acknowledgements

This file inspired Expand.

MATLAB release MATLAB 7.5 (R2007b)
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Comments and Ratings (5)
04 Aug 2009 Russell

Russell

I used replicate.m to generate some padding on a string cell array.

AA = {'blank'};
myLabels = {'fish','beer'};
myLabels = [ myLabels (replicate (AA,1,3)) ]
myLabels =
'fish' 'beer' 'blank' 'blank' 'blank'

08 Dec 2008 Mark Ruzon

Mark Ruzon

This is a more elegant and faster solution for the 2D case. The next version of the file will have this solution. Unfortunately, KRON gives 2D results when Y is 3D, so a different approach is needed in the 3D case.
A = reshape(1:6,[1 3 2]);
S = [2 2 2];
A(kron(reshape(1:numel(A),size(A)),ones(S)))
replicate(A,S)

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06 Dec 2008 Jos (10584)

Jos (10584)

Indexing with KRON is equally flexible:
% data
A = {12 {'yy' 'xxx'} ; 'aaa' rand(2)}
nr = 3 ;
nc = 5 ;
% engine
B = A(kron(reshape(1:numel(A),size(A)),ones([nr nc])))

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05 Dec 2008 Mark Ruzon

Mark Ruzon

KRON works for floats and doubles but not integral types, structs, or cell arrays. KRON relies on multiplication, while REPLICATE uses only indexing, thus making it more flexible.

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05 Dec 2008 Jos (10584)

Jos (10584)

Nice try, but KRON can handle the job perfectly, for instance, kron(A,ones([2, 3]))

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Updates
04 Dec 2008

Bug fix: renamed input parameter.

08 Dec 2008

Sped up 2D case using KRON. Thanks go to Jos.

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