RE: st: could someone pls explain me this

[tashi lama <ltashi32@hotmail.com>]

thank you. I still have some clouds. 

1.Why do we have to summarize the temp var? 

2.Minimum such obs no r(min). Are we looking the minimum obs in the tempvar? Is it 3 in the following example?

 

epcom                 noncom          __000001 |
     |------------------------------------------|
  1. |  18001                Acheres          . |
  2. |  18002         Ainay-Le_Vieil          . |
  3. |  18003   Les Aix -d'Angillion          3 |
  4. |  18004                Allogny          . |
  5. |  18005                Allouis          . |


 

3. Could we have said instead of minimum or maximum no, non-missing obs no because there is only one obs in tempvar?

----------------------------------------
> Date: Mon, 30 Apr 2012 18:37:56 +0100
> Subject: Re: st: could someone pls explain me this
> From: njcoxstata@gmail.com
> To: statalist@hsphsun2.harvard.edu
>
> The code
>
> tempvar tv1
> gene `tv1'=_n if depcom==18003
> summ `tv1', meanonly
> local index=r(min)
> local mymacro=nomcom[`index']
> drop `tv1'
>
> is a way of looking up the value of -nomcom- when -depcom- is 18003.
> The temporary variable contains observation numbers for which -depcom-
> is 18003. A certain way of finding such an observation if any exist is
> to find the minimum such observation number. The maximum would do fine
> as an alternative. The code could be shortened
>
> tempvar tv1
> gene `tv1'=_n if depcom==18003
> summ `tv1', meanonly
> local mymacro=nomcom[r(min)]
> drop `tv1'
>
> The main point of similar code is to automate value look-up. It's
> usually a long-winded way to proceed if you are working interactively.
>
> Nick
>
> On Mon, Apr 30, 2012 at 6:24 PM, tashi lama <ltashi32@hotmail.com> wrote:
>
> > I am doing sth similar to what I found in archive titiled "Re: st: save the value of a string variable into a macro". I am not sure if I followed the code although it looks relatively st. forward.
> >
> >
> >
> > Here is the dataset and goal
> >
> > +-----------------------------+
> > | depcom nomcom |
> > |-----------------------------|
> > 1. | 18001 Acheres |
> > 2. | 18002 Ainay-le-Vieil |
> > 3. | 18003 Les Aix-d'Angillon |
> > 4. | 18004 Allogny |
> > 5. | 18005 Allouis |
> > +-----------------------------+
> >
> > Where depcom is an id. I want to save a specific values of the variable "nomcom" into a variable, for example, I want to obtain :
> > . di "`mymacro'"
> > Archeres
> >
> >
> >
> > The code is
> >
> >
> >
> > tempvar tv1
> > gene `tv1'=_n if depcom==18003
> > summ `tv1', meanonly
> > local index=r(min)
> > local mymacro=nomcom[`index']
> > drop `tv1'
> >
> >
> >
> >
> > I follow line 1 and 2. I am not sure why we need line 3. Line 4 established a macro which is used in line 5. But, I don't follow why the macro takes r(min) as expression. I would think the macro `index' should capture the value(the only value in fact) in tv1.
>
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