Dear R-help I am wondering if somebody wrote some code to convert an adjacency list model into a nested set model. In principal I want to do the same as John Celko mentioned it here with SQL: http://groups.google.co.uk/groups?hl=en&lr=lang_en&selm=8j0n05%24n31%241 %40nnrp1.deja.com
Assume you have a tree structure like this Albert / \ / \ Bert Chuck / | \ / | \ / | \ / | \ Donna Eddie Fred in an adjacency list model: > emp=c("Albert", "Bert", "Chuck", "Donna", "Eddie", "Fred") > boss=c(NA, "Albert", "Albert", "Chuck", "Chuck", "Chuck") > print(Personnel<-data.frame(emp, boss)) emp boss 1 Albert <NA> 2 Bert Albert 3 Chuck Albert 4 Donna Chuck 5 Eddie Chuck 6 Fred Chuck Then it is quite hard to find the all the supervisors of one employee. John's suggestion is to convert the adjacency list model into a nested set model. The organizational chart would look like this as a directed graph: Albert (1,12) / \ / \ Bert (2,3) Chuck (4,11) / | \ / | \ / | \ / | \ Donna (5,6) Eddie (7,8) Fred (9,10) The data is than stored in the following form: > lft=c(1,2,4,5,7,9) > rgt=c(12,3,11,6,8,10) > print(Per<-data.frame(emp, lft, rgt)) emp lft rgt 1 Albert 1 12 2 Bert 2 3 3 Chuck 4 11 4 Donna 5 6 5 Eddie 7 8 6 Fred 9 10 To find now the supervisor of an employee all you have to do is to look where the employees lft figure is between lft and rgt. The supervisors of Eddie are therefore > subset(Per, lft < 7 & rgt > 7) emp lft rgt 1 Albert 1 12 3 Chuck 4 11 In the site mentioned above John provides also some code to transform a adjacency list model into a nested set model. Does somebody know if there is already a package for this in R? Kind Regards Markus Gesmann ************LNSCNTMCS01*************************************************** The information in this E-Mail and in any attachments is CONFIDENTIAL and may be privileged. If you are NOT the intended recipient, please destroy this message and notify the sender immediately. You should NOT retain, copy or use this E-mail for any purpose, nor disclose all or any part of its contents to any other person or persons. Any views expressed in this message are those of the individual sender, EXCEPT where the sender specifically states them to be the views of Lloyd's. Lloyd's may monitor the content of E-mails sent and received via its network for viruses or unauthorised use and for other lawful business purposes." Lloyd's is authorised under the Financial Services and Markets Act 2000 ______________________________________________ R-help@stat.math.ethz.ch mailing list https://stat.ethz.ch/mailman/listinfo/r-help PLEASE do read the posting guide! http://www.R-project.org/posting-guide.html