Hi

I have say a large vector of 3500 digits. Initially the digits are 0s and
1s. I need to check for a rule to change some of the 0s to -1s in this
vector. But once I change a 0 to -1 then I need to start applying the rule
to change the next 0 only after I see the next 1 in the vector.

Say for example x = (0,0,0,0,0,0,0,1,0,0,1,1,0,0,1,0,0,0,1)
I need to traverse from the 9th element to the last ( because the first
occurrence of 1 is at 8) . Let us assume that according to our rule we
change the 13th element (only 0s can be changed) to -1. Now we need to go to
the next occurrence of 1 (which is 15) and begin the rule application from
the 16th till the end of the vector and once replaced a 0 to a -1 then start
again from the next 1. How do we code this? I 'feel' recursion is the best
possible solution but I am not a programmer and will await experts' views.
If this is not a typical R-forum question then my advance apologies.

Many thx
-- 
'Raghu'

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