[R] simple coding question

[Kirsten Beyer]

I have a list of ICD9 (disease) codes with various formats - 3 digit,
4 digit, 5 digit.  The first three digits of these codes are what I am
most interested in.  I would like to either add zeros to the 3 and 4
digit codes to make them 5 digit codes or add decimal points to put
them all in the format ###.##.  I did not see a function that allows
me to do this in the formatting command.  This seems simple - can
someone help?

Thanks,
K.Beyer