Re: [R] sequentially process a list

From: Mike Lawrence <Mike.Lawrence_at_dal.ca>
Date: Mon, 21 May 2007 13:53:37 -0300

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

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Received on Mon 21 May 2007 - 17:24:14 GMT

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