There is a standard trade-off here. It is discussed
at some length in Stata Journal 2(4):411--427 (2002)
with reference to issues like that here, in which there
are direct solutions making use of Stata's built-in functions
and canned solutions making use of an -egen- function.
Broadly speaking,
* Most problems in this area can be solved in a few
lines with calls to Stata's built-in functions, although
it can take some rummaging through the documentation
and some experience to become fluent with this approach.
It also helps to be fluent with -by:-, -_n- and -_N-,
and Stata's handling of true and false.
* An -egen- function, when available, also often offers
the convenience of sensible labelling, attention to missing
values and handles for -if- and -in-. These too are applicable
directly, but some problems can get very messy with these
extra complications.
* However, if you rely on there being a canned solution
to each problem, you will often be sorely disappointed.
There is inevitably some capriciousness in whether
someone has decided that a problem is worth writing an
-egen- function for. (Users cannot write their own built-ins.)
I don't think portability is a major issue provided the
functions concerned are identifiable through -search-
or -findit-, although the need to explain where you got
something can easily be overlooked.
Nick
[email protected]
> -----Original Message-----
> From: [email protected]
> [mailto:[email protected]]On Behalf Of Richard
> Williams
> Sent: 07 March 2004 21:43
> To: [email protected]
> Subject: Re: st: Year to start 1st April
>
>
> At 03:46 PM 3/7/2004 -0500, Nick Winter wrote:
> >At 11:20 PM 3/5/2004 -0500, Richard Williams wrote:
> >>Whoops. I think the original solution I posted quickly gets off a
> >>day. I think it is fixable, but how about this instead:
> >>
> >>. gen finyear = year(datevisit)
> >>
> >>. replace finyear = finyear - 1 if month(datevisit) < 4
> >
> >Just a quick note to note, as it were, that this approach
> can be done in
> >one line:
> >
> > . gen finyear = year(datevisit) - (month(datevisit)<4)
> >
> >(This works because the logical condition will evaluate to 0
> or 1, as
> >appropriate.
> >
> >--Nick Winter
>
> I had tried to do something like that but it wasn't working because I
> didn't have the parentheses on the final part of the
> expression right. For
> those determined to use as few lines as possible, here is yet another
> spacesaver:
>
> . gen finyear = cond(month(datevisit) <
> 4, year(datevisit)-1, year(datevisit))
>
> The -cond- option seems like a nice alternative to a
> generate/replace combo
> of commands.
>
> My favorite solution so far is the ncyear solution suggested
> by Nick Cox -
> not so much because it saves typing but because it saves you
> a lot of time
> figuring out what to type. But, I suppose there is something
> to be said
> for avoiding the use of addons for relatively simple tasks,
> e.g. if the
> code will be run on different machines then portability is
> easier if you
> stick to built-in functions.
>
> *
> * 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/
>
*
* 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/
