R help - Aug 2013 - Iterate over rows and update values based on condition

Hi,

I have a data set with structure similar to this:
id    user    action
1      12      login
2      12      view
3      12      view
4      12      view
5      12      login
6      12      view
7      12      view
8      12      login

I want to create a list of sessions. That means to split table on every
occurrence of "login". Using Java (or some other language), I would
probably iterate through rows and create new List instance on every
"login", but I guess there is more efficient way to do that using R?

Thanks

	[[alternative HTML version deleted]]

Hi,
May be this helps:
dat1<- read.table(text="
id??? user??? action
1????? 12????? login
2????? 12????? view
3????? 12????? view
4????? 12????? view
5????? 12????? login
6????? 12????? view
7????? 12????? view
8????? 12????? login
",sep="",header=TRUE,stringsAsFactors=FALSE)


split(dat1,cumsum(dat1$action=="login"))
#$`1`
?# id user action
#1? 1?? 12? login
#2? 2?? 12?? view
#3? 3?? 12?? view
#4? 4?? 12?? view
#
#$`2`
?# id user action
#5? 5?? 12? login
#6? 6?? 12?? view
#7? 7?? 12?? view
#
#$`3`
?# id user action
#8? 8?? 12? login
A.K.



----- Original Message -----
From: srecko joksimovic <sreckojoksimovic at gmail.com>
To: R-help at r-project.org
Cc: 
Sent: Tuesday, August 27, 2013 3:29 PM
Subject: [R] Iterate over rows and update values based on condition

Hi,

I have a data set with structure similar to this:
id? ? user? ? action
1? ? ? 12? ? ? login
2? ? ? 12? ? ? view
3? ? ? 12? ? ? view
4? ? ? 12? ? ? view
5? ? ? 12? ? ? login
6? ? ? 12? ? ? view
7? ? ? 12? ? ? view
8? ? ? 12? ? ? login

I want to create a list of sessions. That means to split table on every
occurrence of "login". Using Java (or some other language), I would
probably iterate through rows and create new List instance on every
"login", but I guess there is more efficient way to do that using R?

Thanks

??? [[alternative HTML version deleted]]

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