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From |
"Davide Cantoni" <davide.cantoni@gmail.com> |

To |
statalist@hsphsun2.harvard.edu |

Subject |
Re: st: Creating a new variable with information from other observations |

Date |
Mon, 19 May 2008 14:07:44 +0200 |

Wonderful, that is just what I was looking for. Thank you, Maarten and Even. Davide 2008/5/19 Even Bergseng <even.bergseng@umb.no>: > Can -levelsof- help you? > > Best regards, > Even > > >>-----Original Message----- >>From: owner-statalist@hsphsun2.harvard.edu [mailto:owner- >>statalist@hsphsun2.harvard.edu] On Behalf Of Davide Cantoni >>Sent: Monday, May 19, 2008 1:39 PM >>To: statalist@hsphsun2.harvard.edu >>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 <terlist@gmail.com>: >>> 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 >>> <davide.cantoni@gmail.com> 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 >>> Università 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/ > * * 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/

**References**:**st: Creating a new variable with information from other observations***From:*"Davide Cantoni" <davide.cantoni@gmail.com>

**Re: st: Creating a new variable with information from other observations***From:*"Teresio Poggio" <terlist@gmail.com>

**Re: st: Creating a new variable with information from other observations***From:*"Davide Cantoni" <davide.cantoni@gmail.com>

**RE: st: Creating a new variable with information from otherobservations***From:*Even Bergseng <even.bergseng@umb.no>

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