# How to generate sequences from two vectors using rowfun

3 views (last 30 days)
Etsuko on 13 Jul 2016
Edited: Stephen23 on 13 Jul 2016
Hi,
I am trying to generate sequences for which starting values and last values+1 are contained in vectors, without using for-loop. Because there is a lot of data to process, doing for-loop is unfortunately not feasible. As the output, I want to have all the sequences to be concatenated into one vector. I think rowfun can help me here, but so far I have not been successful. If someone can give me a helping hand, I would be grateful.
This is an example;
x = [1,6,12]'; y = [5,10,13]';
the output I wish to obtain: z = [1,2,3,4,6,7,8,9,12];
I imagine it should be something like;
inputvecs = table(x,y);
z = rowfun(@seqgen,inputvecs)
How should the function seqgen look in this case? Should concatenation within the function?
Thank you very much for your help.
Etsuko

Stephen23 on 13 Jul 2016
Edited: Stephen23 on 13 Jul 2016
>> x = [1,6,12]; y = [5,10,13];
>> cell2mat(arrayfun(@(a,b)a:b-1, x,y,'UniformOutput',false))
ans =
1 2 3 4 6 7 8 9 12
or
>> tmp = arrayfun(@(a,b)a:b-1,x,y,'UniformOutput',false);
>> horzcat(tmp{:})
ans =
1 2 3 4 6 7 8 9 12
Note that the inputs must be horizontal vectors.
Etsuko on 13 Jul 2016
Edited: Etsuko on 13 Jul 2016
Thank you so much for your help, Stephen and Andrei!
Here I compared time for these three methods;
>> x = [1,6,12]; y = [5,10,13];
>> tic; cell2mat(arrayfun(@(a,b)a:b-1, x,y,'UniformOutput',false)); toc
Elapsed time is 0.008368 seconds.
>> tic; tmp = arrayfun(@(a,b)a:b-1,x,y,'UniformOutput',false);horzcat(tmp{:}); toc
Elapsed time is 0.000757 seconds.
>> tic; a = (min(x):max(y))';[ii,~] = find(bsxfun(@ge,a,x)&bsxfun(@lt,a,y));out = a(ii);toc
Elapsed time is 0.003983 seconds.
Thank you!
Stephen23 on 13 Jul 2016
Edited: Stephen23 on 13 Jul 2016
@Etsuko: note that to get meaningful timing values for such quick functions, it is recommended to repeat the process a few hundred or thousand times.

Andrei Bobrov on 13 Jul 2016
Edited: Andrei Bobrov on 13 Jul 2016
x = [1,6,12]; y = [5,10,13];
a = (min(x):max(y))';
[ii,~] = find(bsxfun(@ge,a,x)&bsxfun(@lt,a,y));
out = a(ii);
Etsuko on 13 Jul 2016
Thank you very much! It worked.

### Categories

Find more on Logical in Help Center and File Exchange

### Community Treasure Hunt

Find the treasures in MATLAB Central and discover how the community can help you!

Start Hunting!