Try this: > aggregate(Project~Country+Iso, df, length) Country Iso Project 1 Burkina Faso BF 2 2 Ethiopia ET 1 3 Ghana GH 1 4 Kenya KE 2 5 Madagascar MG 2 6 Mali ML 1 7 Mozambique MZ 1 8 Nigeria NG 1 9 Tanzania TZ 2 10 South Africa ZA 2 11 Zimbabwe ZW 1
Or if you prefer left-aligned: > print(aggregate(Project~Country+Iso, df, length), right=FALSE) Country Iso Project 1 Burkina Faso BF 2 2 Ethiopia ET 1 3 Ghana GH 1 4 Kenya KE 2 5 Madagascar MG 2 6 Mali ML 1 7 Mozambique MZ 1 8 Nigeria NG 1 9 Tanzania TZ 2 10 South Africa ZA 2 11 Zimbabwe ZW 1 ------------------------------------- David L Carlson Associate Professor of Anthropology Texas A&M University College Station, TX 77840-4352 -----Original Message----- From: r-help-boun...@r-project.org [mailto:r-help-boun...@r-project.org] On Behalf Of Arnaud Michel Sent: Wednesday, June 19, 2013 9:23 AM To: r-help@r-project.org Subject: [R] to build a data.frame Hello I have the following dataframe df <- data.frame( Project=c("Abaco","Abaco","Abac","Abaco","Abaco","Abaco", "Abaco","Adaptclone","Adaptclone","Adaptclone","Adaptclone","Adaptcl one", "Adaptclone","Adopt","Adopt","Adopt"), Country=c("Zimbabwe","Burkina Faso","South Africa","Madagascar","Tanzania", "Mali","Mozambique","Madagascar","Ghana","Nigeria","Kenya","Burkina Faso", "South Africa","Tanzania","Kenya","Ethiopia" ), Iso=c("ZW","BF","ZA","MG","TZ","ML","MZ","MG","GH","NG","KE","BF", "ZA","TZ","KE","ET")) I would like to build a other dataframe with name Country where column 1 is country, the column 2 is number of project (in the country) the column 3 is the code Iso (wich correspond with the country : Ex ZW is ISO of Zimbabwe) Pays PaysIso NbrProj Zimbabwe ZW 1 Burkina Faso BF 2 I know associate Country and Number of projets but how associate Iso Any idea ? Thank you for your help -- Michel ARNAUD Chargé de mission auprès du DRH DGDRD-Drh - TA 174/04 Av Agropolis 34398 Montpellier cedex 5 tel : 04.67.61.75.38 fax : 04.67.61.57.87 port: 06.47.43.55.31 ______________________________________________ R-help@r-project.org mailing list https://stat.ethz.ch/mailman/listinfo/r-help PLEASE do read the posting guide http://www.R-project.org/posting-guide.html and provide commented, minimal, self-contained, reproducible code. ______________________________________________ R-help@r-project.org mailing list https://stat.ethz.ch/mailman/listinfo/r-help PLEASE do read the posting guide http://www.R-project.org/posting-guide.html and provide commented, minimal, self-contained, reproducible code.