Can -levelsof- help you?
Best regards,
Even
>-----Original Message-----
>From: [email protected] [mailto:owner-
>[email protected]] On Behalf Of Davide Cantoni
>Sent: Monday, May 19, 2008 1:39 PM
>To: [email protected]
>Subject: Re: st: Creating a new variable with information from other
>observations
>
>Thank you, Teresio. That works fine.
>
>More generally, could I ask you statalisters again about the last
>doubt I expressed in my previous email, i.e.:
>
>:: is there a way to run a "foreach" over all (numeric) values that a
>given variable takes, without having to specify exactly the values
>that this variable takes? Ok, I see, in most cases this would be a job
>for "by(sort)", but I cannot help thinking that there are some cases
>in which bysort does not help me -- for example when I want to run
>more than one command, as I would do within the braces of
>"foreach...", or when the units the loop runs over (the `X' in
>"foreach X", so to speak) are used in some logical condition.
>
>In brief: is there a way to create a numlist from the unique values
>that a variable takes? Or how would you proceed?
>
>Thanks,
>
>Davide
>
>
>
>2008/5/18 Teresio Poggio <[email protected]>:
>> Dear Davide,
>>
>> from your dataset I'd build a just capitals dataset:
>> - select just the capitals (drop if cityid !=capitalid)
>> - in the new dataset keep just capitalid and latitude
>> - rename latitude into latitude_capital
>> - sort the data by capitalid and save it
>>
>> then open you original data set and sort it by capitalid,
>> merge it with the new "just capital dataset" using capitalid as a key
>> and the option uniqmaster
>> (help merge for details)
>>
>> Hope this helps.
>>
>> Teresio
>>
>> On Sun, May 18, 2008 at 2:22 PM, Davide Cantoni
>> <[email protected]> wrote:
>>> Hello,
>>>
>>> I am having a rather intricate problem in creating a new variable in
>a
>>> panel dataset, and I appreciate any help you could offer. I hope the
>>> problem can potentially be of general interest.
>>>
>>> I have a panel dataset of cities and their characteristics in
>>> different countries. I know the latitude of each one of these cities,
>>> but now I want to create an additional variable reflecting the
>>> latitude of the capital city of the country a given city lies in. So
>>> for example: for the cities of New York, Chicago, etc., I want this
>>> new variable to contain the latitude of Washington, DC.
>>>
>>> Here is a description of the dataset's structure: it is a panel in
>>> long form, with cities in different countries, observed over
>different
>>> years. Each city has a unique numeric identifier, "cityid". Then
>there
>>> is a country identifier, called "countryid". Finally, there is a
>>> variable that repeats the capital city's cityid for each city in a
>>> given country, "capitalid". For instance, if the cityid of London was
>>> 135, all cities in the dataset that are in the UK would get a value
>of
>>> 135 in the variable "capitalid". Finally, there is a variable called
>>> "latitude" that refelcts the latitude of each city.
>>>
>>> How would I now proceed to create this new variable, call it
>>> "latitude_capital", by using the variables above?
>>>
>>> Basically, the problem I'm having is
>>> - tell stata to look up for each city its capitalid
>>> - browse the dataset until you find a city that has the cityid equal
>>> to this capitalid
>>> - find out the latitude of this capital city
>>> - go back to the original city and replace "latitude_capital" with
>the
>>> latitude you've just retrieved
>>>
>>> The additional problem I encounter while trying to construct
>something
>>> with "foreach..." (that, at least, is what I was trying so far) is
>>> that the values that the capitalid variable takes are of course not a
>>> clean numlist (like "1(1)100"), but rather a sequence of numbers
>>> without any regularity, such as 11 12 50 54 60 131... and so on.
>>> Thanks for your suggestions!
>>>
>>> Davide Cantoni
>>> *
>>> * 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/
>>>
>>
>>
>>
>> --
>> ____________________________________________________
>> dr. Teresio Poggio
>> LaboR - Dipartimento di Sociologia e ricerca sociale
>> Universit� degli studi di Trento
>> Piazza Venezia, 41
>> 38100 Trento, Italy
>> Tel +39 0461/881406
>> fax: +39 0461/881348
>>
>> *
>> * 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/
*
* 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/
