[R] aggregate and list elements of variables in data.frame

[Massimo Bressan]

sorry, but by further looking at the example I just realised that the posted solution it's not completely what I need because in fact I do not need to get back the 'indices' but instead the corrisponding values of column A 

#please consider this new example 

t<-data.frame(id=c(18,91,20,68,54,27,26,15,4,97),A=c(123,345,123,678,345,123,789,345,123,789)) 
t 

# I need to get this result 
r<-data.frame(unique_A=c(123, 345, 678, 789),list_id=c('18,20,27,4','91,54,15','68','26,97')) 
r 

# any help for this, please? 





Da: "Massimo Bressan" <massimo.bressan using arpa.veneto.it> 
A: "r-help" <R-help using r-project.org> 
Inviato: Giovedì, 7 giugno 2018 10:09:55 
Oggetto: Re: aggregate and list elements of variables in data.frame 

thanks for the help 

I'm posting here the complete solution 

t<-data.frame(id=1:10,A=c(123,345,123,678,345,123,789,345,123,789)) 
t$A <- factor(t$A) 
l<-sapply(levels(t$A), function(x) which(t$A==x)) 
r<-data.frame(list_id=unlist(lapply(l, paste, collapse = ", "))) 
r<-cbind(unique_A=row.names(r),r) 
row.names(r)<-NULL 
r 

best 



Da: "Massimo Bressan" <massimo.bressan using arpa.veneto.it> 
A: "r-help" <R-help using r-project.org> 
Inviato: Mercoledì, 6 giugno 2018 10:13:10 
Oggetto: aggregate and list elements of variables in data.frame 

#given the following reproducible and simplified example 

t<-data.frame(id=1:10,A=c(123,345,123,678,345,123,789,345,123,789)) 
t 

#I need to get the following result 

r<-data.frame(unique_A=c(123, 345, 678, 789),list_id=c('1,3,6,9','2,5,8','4','7,10')) 
r 

# i.e. aggregate over the variable "A" and list all elements of the variable "id" satisfying the criteria of having the same corrisponding value of "A" 
#any help for that? 

#so far I've just managed to "aggregate" and "count", like: 

library(sqldf) 
sqldf('select count(*) as count_id, A as unique_A from t group by A') 

library(dplyr) 
t%>%group_by(unique_A=A) %>% summarise(count_id = n()) 

# thank you 


-- 

------------------------------------------------------------ 
Massimo Bressan 

ARPAV 
Agenzia Regionale per la Prevenzione e 
Protezione Ambientale del Veneto 

Dipartimento Provinciale di Treviso 
Via Santa Barbara, 5/a 
31100 Treviso, Italy 

tel: +39 0422 558545 
fax: +39 0422 558516 
e-mail: massimo.bressan using arpa.veneto.it 
------------------------------------------------------------ 


-- 

------------------------------------------------------------ 
Massimo Bressan 

ARPAV 
Agenzia Regionale per la Prevenzione e 
Protezione Ambientale del Veneto 

Dipartimento Provinciale di Treviso 
Via Santa Barbara, 5/a 
31100 Treviso, Italy 

tel: +39 0422 558545 
fax: +39 0422 558516 
e-mail: massimo.bressan using arpa.veneto.it 
------------------------------------------------------------ 

	[[alternative HTML version deleted]]