Nick
You say 'Stata isn't good at extra-sensory perception' however the command -use- can manage it...
. clear
. use auto.dta if foreign==1
(1978 Automobile Data)
. tab foreign
Car type | Freq. Percent Cum.
------------+-----------------------------------
Foreign | 22 100.00 100.00
------------+-----------------------------------
Total | 22 100.00
. clear
. use auto.dta in 1/10
(1978 Automobile Data)
. count
10
The syntax looks standard, but cannot be parsed by the -syntax- command. Suppose the program I wanted to write was as follows (in reality it is more complex, obviously)...
program foo
syntax [name] [if] [in] [, *]
use `namelist'.dta `if' `in' , `options'
end
Then...
. clear
. foo auto if foreign==1
foreign not found
r(111);
. foo auto in 1/10
Obs. nos. out of range
r(198);
So what I am trying to work out is how to manually parse the input (using -gettoken- and the like) to identify the name (if there is one), if statement (if there is one), in statement (if there is one) and options (if any are specified).
I could get around it by putting the [if] and [in] as options instead, eg
syntax [name] [, ifopt(string) inopt(string) *]
but this goes against the appeal of the intuitive standard syntax of Stata, so I wondered if anyone had overcome this problem before?
David
[email protected]
Nick Cox
> I don't however understand the bit about
> variables not in memory. Stata isn't good
> at extra-sensory perception...
>
> David Harrison
>
> > I want to write a command with the syntax
> >
> > command [name] [if exp] [in range] [, opt1 opt2 *]
> >
> > BUT, the -if exp- and -in range- are to be applied in a -use-
> > statement, so they may involve variables that are not in the
> > dataset in memory. Any suggestions on how I can parse this to
> > get the locals `namelist' `if' `in' `opt1' `opt2' and
> > `options' that would be produced by -syntax-?
> >
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