spitting up a character

I want to split up any given number (as a character) with "," in such a way that if there is a 2 or a 6, it and the next digit are taken as a pair and put a "," around them.

e.g. '1357320676222345' would become '13573,20,67,62,22,345'

my attempts just end up just putting a lot of ',' around the first pair that meets this condition

I realise it has to do with the fact the character length keeps increasing with each itteration, but I don't know how to get around this problem.

clear
c = '1357320676222345'

L = length(c)

for i = 1:L
    
    if c(i) == '2'
        j = i
        c = insertBefore(c,i,',')
        c = insertAfter(c,i+2,',')
        
        continue
        
    end
    if c(i) == '6'
        j = i
        c = insertBefore(c,i,',')
        c = insertAfter(c,i+2,',')
        
        continue
    end
end 

Answer 1

[tmarske]

Try doing it in two passes, one to add a comma before, another to add one after:

c = '1357320676222345'
c = regexprep(c, '([26]\d)', ',$1')
c = regexprep(c, '([26]\d)[^,]', '$1,')

The first regexprep adds a comma before each instance, the second adds one after, so long as there is not one already present.

Check that this is actually the behaviour you want (how '62' should be treated, whether you want commas at the beginning or end of the character sequence, etc.)

Answer 2

[Daniel Dolan]

How about htis?

clear
c = '1357320676222345';
L = length(c);

out=repmat('0',[1 3*L]);
i=1;
k=1;
while i < L
    if (c(i) == '2') || (c(i) == '6')
        out(k:k+3)=[',' c(i:i+1) ','];
        k=k+4;
        i=i+2;
    else
        out(k)=c(i);
        k=k+1;
        i=i+1;
    end
end
out(k)=c(end);
c=out(1:k);
c=strrep(c,',,',',')