Re: st: Creating single characters from long strings

[Margaret R Grove <margaret.r.grove@Dartmouth.EDU>]

Thanks much, Nick!  I should have known that one ... it has messed up my 
code on a few occasions. 
Meg

Nick Cox wrote:

> You had, for a string variable -variable-, 
> local len = length(variable) 
> But as -variable- is a variable, what precisely goes into -len-? The
> answer is that Stata uses the value for the first observation, i.e. that
> is equivalent to 
> local len = length(variable[1]) 
> That would be the right answer for your purpose whenever -variable[1]-
> was no shorter than any other value. But there is no summary role
> whereby -length()- looks at the entire set of values and works out some
> summary length (e.g. the maximum, which is most often wanted in my
> experience). As far as -length()- is concerned, it can only take a
> single string argument whenever the assignment is to a macro. 
> The same issue arises whenever you do something like 
> . sysuse auto, clear
> . di make 
> What gets displayed? Answer: make[1]. 
> I have sympathies with anyone who says that this kind of input should
> have been classed as a syntax error, but right at the beginning of Stata
> it was decided that it was legal. My guess is that Stata's designers
> decided that they would rather see some output than be stopped by a
> syntax error. 
> Nick
> n.j.cox@durham.ac.uk 
> Margaret R Grove
>
> Ah yes - early morning fog here!  No `j' needed.  Nick - I'm not sure 
> what you mean about the length(variable) note.  I tried running that 
> little program and it did what I wanted.
>
>
> Nick Cox wrote:
>   
> > For a string variable, -length(variable)- is equivalent to
> > -length(variable[1])-. That may or may not be a correct answer. 
> > Also `j' is the same as `i' here. 
> > Nick
> > n.j.cox@durham.ac.uk 
> > Margaret R Grove
> >
> > Andri,
> >
> > Perhaps something like this ....
> >
> > local len=length(variable)
> > local j=0
> > forval i=1/`len' {
> >     local j=`j'+1
> >     gen str1 var`j'=substr(variable,`i',1)
> > }
> >
> > Meg
> >
> > Andri Rauch wrote:
> >   
> >     
> > > Dear all,
> > > I should create single characters from very long strings (ie around
> > >     
> > >       
> > 500
> >   
> >     
> > > characters).
> > > My original variable abcdefg... should be transformed to:
> > > variable_1: a, variable_2: b, variable_3: c, variable_4: d and so
> > >     
> > >       
> > on...
> >   
> >     
> > > I assume it should be done by combining the substring and foreach
> > > command.
> > >     
> > >       
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