[R] sequentially process a list

[Mike Lawrence]

Sorry, obviously misread your help request. Jim's solution is what  
you're looking for.

On 21-May-07, at 12:56 PM, Mike Lawrence wrote:

> Try nested ifelse() statements to label the group
>
> ex.
> time$group=ifelse(time$time<5,NA,
> 	ifelse(time$time<9,1,
> 		ifelse(time$time<13,NA,
> 			ifelse(time$time<17,2,NA)
> 		)
> 	)
> )
>
> Then use aggregate to find the max value.
>
> ex.
> time.max=aggregate(time$value,list(group=time$group),max)
>
>
> On 21-May-07, at 6:39 AM, Robert wrote:
>
>> Hi dear R users,
>>
>> I'm a R beginner and I have a basic question about sequential
>> treatments of lists.
>>
>> I have a time based (i.e. events are consecutive) list of values of
>> a biological property.
>>
>> Like :
>>
>> time  value
>> 1        5
>> 2        10
>> 3      7
>> 4      10
>> 5      19
>> 6      21
>> 7      20
>> 8      18
>> 9      10
>> 10      7
>> 11      8
>> 12      12
>> 13      17
>> 14      19
>> 15      24
>> 16      18
>> 17      15
>> 18      10
>> 19      9
>> [...]
>>
>>
>> And I have to define a threshold and to attach each event to his
>> group, i.e. values upper the threshold.
>>
>> Like, for a threshold value of 17
>>
>> time  value   group
>> 1        5       NA
>> 2        10      NA
>> 3      7      NA
>> 4      10      NA
>> 5      19      1
>> 6      21      1
>> 7      20      1
>> 8      18      1
>> 9      10      NA
>> 10      7      NA
>> 11      8      NA
>> 12      12      NA
>> 13      17      2
>> 14      19      2
>> 15      24      2
>> 16      18      2
>> 17      15      NA
>> 18      10      NA
>> 19      9      NA
>> [...]
>>
>>
>> The only solution that I have found is to do a sequentially read
>> and write :
>> for(i in 1:length(my_events_list))
>> {
>>     [...]
>> }
>>
>> But I very slow. Do you have another ideas ?
>>
>> And after I need to extract maximum values for each group
>> Like :
>> group        max_value
>> 1            21
>> 2            24
>> [...]
>>
>> and for each event which is part of a group to know if is't a
>> ascending phase or no.
>>
>>
>> Yes, lot of questions !! Sorry, but I think that the solution may
>> be unique.
>>
>> In advance, thank you a lot
>>
>> regards
>>
>> JS
>>
>>
>>
>>
>>
>>
>>
>>
>> _____________________________________________________________________ 
>> _
>> _______
>>
>> ______________________________________________
>> R-help at 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
>> and provide commented, minimal, self-contained, reproducible code.
>
> --
> Mike Lawrence
> Graduate Student, Dalhousie University Department of Psychology
> http://myweb.dal.ca/mc973993
>
> "The road to wisdom? Well, it's plain and simple to express:
> Err and err and err again, but less and less and less."
> - Piet Hein
>
> ______________________________________________
> R-help at 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
> and provide commented, minimal, self-contained, reproducible code.

--
Mike Lawrence
Graduate Student, Dalhousie University Department of Psychology
http://myweb.dal.ca/mc973993

"The road to wisdom? Well, it's plain and simple to express:
Err and err and err again, but less and less and less."
- Piet Hein