Hi Nick,
I will read more into the tip you gave.. When I gave the command you suggested
by id : gen prev = city[1]
by id : list prev city if prev != city & _n == 2
it just lists all the ids... one by one... Doesn't solve the problem.
Thanks.
Rijo.
On Fri, Nov 21, 2008 at 11:26 AM, Nick Cox <[email protected]> wrote:
> This synthetic example shows that the command will list precisely those
> observations that differ from the previous observation. But this
> includes the first, as city[0] evaluates to string missing, i.e. "".
> More generally, varname[0] is regarded as missing in the sense of the
> variable's data type, i.e. numeric missing . or string missing "". So
> the first in each group will always be listed (unless its value is
> missing).
>
> . l
>
> +------------+
> | city |
> |------------|
> 1. | Durham, UK |
> 2. | Durham, UK |
> 3. | Durham, UK |
> 4. | Durham, NC |
> 5. | Durham, NC |
> |------------|
> 6. | Durham, NH |
> 7. | Durham, NH |
> 8. | Durham, NH |
> 9. | Durham, NH |
> 10. | Durham, NH |
> +------------+
>
> . list if city != city[_n-1]
>
> +------------+
> | city |
> |------------|
> 1. | Durham, UK |
> 4. | Durham, NC |
> 6. | Durham, NH |
> +------------+
>
> You probably want
>
> by id : gen prev = city[1]
> by id : list prev city if prev != city & _n == 2
>
> There is no royal road to cleaning up string variables. The matter was
> discussed on the list earlier this year and written up as a Tip:
>
> SJ-8-3 dm0039 . . . Stata tip 64: Cleaning up user-entered string
> variables
> . . . . . . . . . . . . . . . . . . . . . . . . J. Herrin and
> E. Poen
> Q3/08 SJ 8(3):444--445 (no
> commands)
> tip on how to clean up user-entered string variables
>
> Nick
> [email protected]
>
> Rijo John
>
> I have a data set as follows
>
> ID City Year
> 1 City name 1
> 1 City name 2
>
>
> The data is suppose to have same city names for each ids for year 1
> and two. but there are many occasions where city for the year 1 is
> spelt differently thanthat for year 2. I just want to list out or edit
> those cities where city names are different for year 1 and 2 for the
> same ID. When I issue the following command
>
> bysort ID : list if City!=City[_n-1]
>
> it lists all observations in the data whether or not the city is spelt
> differently in years one and two. Thats strange to me? Can someone
> tell what I am doing wrong here?
>
>
> *
> * For searches and help try:
> * http://www.stata.com/help.cgi?search
> * http://www.stata.com/support/statalist/faq
> * http://www.ats.ucla.edu/stat/stata/
>
--
Rijo M John,
Institute for Health Research and Policy (MC 275),
1747 West Roosevelt Road, Room 558,
Chicago, Illinois 60608.
Ph: 312-413-9057
Fax: 312-355-2801
URL: http://ihrp-web.ihrp.uic.edu/
*
* For searches and help try:
* http://www.stata.com/help.cgi?search
* http://www.stata.com/support/statalist/faq
* http://www.ats.ucla.edu/stat/stata/
