Help-Rs,
I'm doing some string manipulation in a file where I converted a string date in
mm/dd/yyyy format and returned the date yyyy.
I've used regexpr (hat tip to Gabor G for a very nice earlier post on this
function) in steps (I've un-nested the code and provided it and an example of
what I did below. My question is: is there a more efficient way to do this.
Specifically is there a way to use regexpr or some other string function to
return not the first instance, but the 2nd (or for that matter 3rd, 4th or 5th
instance) of a certain string?
#first find the first occurence of "/" and create a variable for this
firstslash <- unlist(regexpr("/", dates, fixed = TRUE)) #then use frist/ to cut
the string field into an intermediate variable e.g., from 1/1/2008 to 1/2008.
step1 <- substr( dates, (firstslash + 1), nchar(dates) ) #then repeat steps 1
and 2...there's got to be a better way step2 <- unlist(regexpr("/", step1,
fixed = TRUE)) #then use step2 to cut string into final product e.g., from
1/2008 to 2008. final <- substring(step1,step2 + 1, nchar(step1) )
Thx!
C
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