Hi, May be this helps: dat1<- read.csv("dat7.csv",header=TRUE,stringsAsFactors=FALSE,sep="\t") dat.bru<- dat1[!is.na(dat1$evnmt_brutal),] fun2<- function(dat){?? ????? lst1<- split(dat,dat$patient_id) ??? lst2<- lapply(lst1,function(x) x[cumsum(x$evnmt_brutal==0)>0,]) ??? lst3<- lapply(lst2,function(x) x[!(all(x$evnmt_brutal==1)|all(x$evnmt_brutal==0)),]) ??? lst4<- lst3[lapply(lst3,nrow)!=0] ??? lst5<- lapply(seq_along(lst4),function(i){ ??? ??? ??? ??? ???? do.call(rbind,lapply(which(lst4[[i]]$evnmt_brutal==1),function(x) { ??? ??? ??? ??? ??? ??? ??? ??? ??? ??? x1<-c(x-2,x-1,x) ??? ??? ??? ??? ??? ??? ??? ??? ??? ??? x2<-x1[!any(x1==0)] ??? ??? ??? ??? ??? ??? ??? ??? ??? ??? x3<-lst4[[i]][x2,] ??? ??? ??? ??? ??? ??? ??? ??? ??? ??? x4<-x3[!is.na(match(paste(x3$evnmt_brutal,collapse=""),"001")),] ??? ??? ??? ??? ??? ??? ??? ??? ??? ??? x4[!any(duplicated(x4$number))] ??? ??? ??? ??? ??? ??? ??? ??? ??? ??? } ??? ??? ??? ??? ??? ??? ??? ??? ??? ??? )) ??? ??? ??? ??? ??? ??? ??? ??? ??? }) ?? lst6<-lst5[lapply(lst5,nrow)!=0] ?? names(lst6)<- unlist(lapply(lst6,function(x) unique(x$patient_id))) ?? Mean0bet_01<- do.call(rbind,lapply(lst6,function(x) mean(x[seq(nrow(x))%%3==2,"basdai_d"]))) ?? lst7<-list(lst6,Mean0bet_01) ?? lst7 ?? #lapply(lst7,head,2)??? ?? }?? ??? ??? ??? ??? fun2(dat.bru) ##output from first 2 patients #[[1]] #[[1]]$`2` ?# ? X patient_id number responsed_at? t basdai_d evnmt_brutal #13 13????????? 2???? 12?? 2011-07-05 12???? -1.0??????????? 0 #14 14????????? 2???? 13?? 2011-08-07 13????? 0.9??????????? 0 #15 15????????? 2???? 14?? 2011-09-11 14???? -0.8??????????? 1 # #[[1]]$`5` #??? X patient_id number responsed_at t basdai_d evnmt_brutal #52 52????????? 5????? 8?? 2011-01-11 7???? -2.8??????????? 0 #53 53????????? 5????? 9?? 2011-02-13 8????? 0.0??????????? 0 #54 54????????? 5???? 10?? 2011-03-19 9???? -1.2??????????? 1 # #[[2]] ?# [,1] #2? 0.9 #5? 0.0 A.K. ________________________________ From: GUANGUAN LUO <guanguanluo at gmail.com> To: arun <smartpink111 at yahoo.com> Sent: Tuesday, June 4, 2013 3:54 AM Subject: choose the lines2 Hello, Arun,? now it is nearly the same problem. I want to know if I want to choose three period : one line with evnmt_brutal ==0 , one line with evnmt_brutal==0 and one line with evnmt_brutal==1, then I want to choose the second and third period for each patient, so that i can calculate the average of scores of basdai when evnmt_brutal==0 (in condition that the precedent line with evnmt_brutal==0) and evnmt_brutal==1. In writing with the phrase "if", if i have two conditions, i don't know how can i write that. This is when i want to choose the period with evnmt_brutal ==0 et evnmt_brutal==1 for each patient, you have written this code. If i want to add one condition that before the line evnmt_brutal==0, evnmt_brutal of that line equal to 0 too.? The result i want to get is just the two last lines. Do you know how can i realize that? dat1<- read.csv("dat7.csv",header=TRUE,stringsAsFactors=FALSE,sep="\t") dat.bru<- dat1[!is.na(dat1$evnmt_brutal),] fun1<- function(dat){??? ? ??? lst1<- split(dat,dat$patient_id) ??? lst2<- lapply(lst1,function(x) x[cumsum(x$evnmt_brutal==0)>0,]) ??? lst3<- lapply(lst2,function(x) x[!(all(x$evnmt_brutal==1)|all(x$evnmt_brutal==0)),]) ??? lst4<-lapply(lst3,function(x) {vect.brutal=c() ??? ??? ??? ??? for(line in which(x$evnmt_brutal==1)){ ??? ??? ??? ??? ?? if(x$evnmt_brutal[line-1]==0){ ??? ??? ??? ??? ? vect.brutal=c(vect.brutal,line) ??? ??? ??? ??? ??? } ??? ??? ??? ??? ??? ?? } ??? ??? ??? ????? vect.brutal1<- sort(c(vect.brutal,vect.brutal-1)) ??? ??? ??? ???? x[vect.brutal1,] ??? ??? ??? ??? ??? ?? } ??? ??? ??? ??? ??? ?? ) ??? res<- do.call(rbind,lst4) ??? row.names(res)<- 1:nrow(res) ??? res ??? } fun1(dat.bru)head(fun1(dat.bru),10) #??? X patient_id number responsed_at? t basdai_d evnmt_brutal #1? 14????????? 2???? 13?? 2011-08-07 13??? 0.900??????????? 0 #2? 15????????? 2???? 14?? 2011-09-11 14?? -0.800??????????? 1 #3? 22????????? 3????? 2?? 2010-06-29? 1?? -0.800??????????? 0 #4? 23????????? 3????? 3?? 2010-08-05? 2??? 0.000??????????? 1 #5? 24????????? 3????? 4?? 2010-09-05? 3??? 1.200??????????? 0 #6? 25????????? 3????? 5?? 2010-10-13? 4??? 1.925??????????? 1 #7? 26????????? 3????? 6?? 2010-11-15? 5?? -2.525??????????? 0 #8? 27????????? 3????? 7?? 2010-12-18? 6?? -0.200??????????? 1 #9? 53????????? 5????? 9?? 2011-02-13? 8??? 0.000??????????? 0 #10 54????????? 5???? 10?? 2011-03-19? 9?? -1.200??????????? 1