st: scrolling over observations

["Dr. J. Clovis, Economics" <Joel.Clovis@bristol.ac.uk>]

Dear listers,

I have been trying to scroll through observations of a variable and assign 
an identifying code to each occurrence of a key value.

For example, I want to scroll though the variable CoName and give each 
occurrence of the company BCA, say, the code 4, say. I want to arrange it 
so that the 1st company (in alpha order) receives code 1 and the last, 680 
or whatever is the maximum number of companies in the database.

I have tried the following which gives me a '1' at the start of the 
occurrence of a new company name and zeros for all other occurrences for 
that company:

gen new=0
local count =0
bysort CoName: replace new = `count'+1  if CoName[_n] ~= CoName[_n-1]
count = `count'+1


Can anyone say where I'm going wrong.  It may help to know that I do not 
know 'a priori' the number of companies in the dataset or indeed how many 
times each companies is observed.

I did look at the FAQs on the STATA website but could not understand much 
of what was said there.  Although the for command should help, I can't seem 
to get it to do the above.

I have been away from this list for a number of years and so protocol may 
have moved on, so if I am breaching any please excuse my ignorance.

Thanks in advance

Kind regards

J.S. Clovis,

*
*   For searches and help try:
*   http://www.stata.com/support/faqs/res/findit.html
*   http://www.stata.com/support/statalist/faq
*   http://www.ats.ucla.edu/stat/stata/