Combining arrays to form indices

I'm wondering if there's a method to combine 2 linear arrays for matrix indexing purposes.

For example given the arrays:

A = [1 10 15 25 35]

B = [5 13 18 31 52]

How would one create an indexing array such as:

C = [1:5 10:13 15:18 25:31 35:52]

Hopefully that makes sense, thanks for the help!

Answer 1

[dpb]

One way...

C=cell2mat(arrayfun(@colon,A,B,'uniformoutput',false));

[Robert]

Thank you! That works perfectly for my application.

Answer 2

[Chad Greene]

I like dpb's solution. My slower, clunkier solution would have required a loop:

A = [1 10 15 25 35];
B = [5 13 18 31 52];

m = 1; 
for n = 1:length(A)
    d = A(n):B(n); 

      C(m:m+length(d)-1) = d; 
      m = m+length(d); 
end

[dpb]

The thing in coming up w/ such solutions is to remember that Matlab operators like : are implemented as functions syntactically so that there's always a functional name form (here colon, of course) to use where need a function handle or the like. It's always easier to think of with "real" functions like mean, say, whereas it's easy to forget about the symbols having alias names because they're not used as often.

Answer 3

[Andrei Bobrov]

x(B+1)=-1;
x(A)=1;
out = A(1):B(end)+1;
out = out(cumsum(x)>0);