HI Ajay,
On Fri, Feb 17, 2012 at 3:20 PM, Ajay Askoolum <aa2e...@yahoo.co.uk> wrote:
> Given
>
> dayOfWeekName<-c("Mon","Tue","Wed","Thu","Fri","Sat","Sun");
> dayOfWeekOrdinal<-c(1,2,3,4,5,6,0);
> dayOfWeekWorkDay<-c(TRUE,TRUE,TRUE,TRUE,TRUE,FALSE,FALSE);
>
> weekProfile<-list(dow=dayOfWeekName,dowI=dayOfWeekOrdinal,dowW=dayOfWeekWorkDay)
>
>
> 1. How can I conditionally get dow, dowI, and dowW from weekProfile?
>
> If another 'arrangement' of this list object will make this task easier,
> please advise.
> 2. What is the point of the list object?
>
> I know that when mixed data types need to be held together, then the only
> option is to use the list data structure.
In your particular case, where all list components are the same length and are
associated with each other in order, a special type of list called a data frame
is easier to work with.
weekProfile<-
data.frame(dow=dayOfWeekName,dowI=dayOfWeekOrdinal,dowW=dayOfWeekWorkDay)
> weekProfile
dow dowI dowW
1 Mon 1 TRUE
2 Tue 2 TRUE
3 Wed 3 TRUE
4 Thu 4 TRUE
5 Fri 5 TRUE
6 Sat 6 FALSE
7 Sun 0 FALSE
I'm not sure what kind of conditional you want, but this can easily be done
with subset() or [
> weekProfile[weekProfile$dowW ,]
dow dowI dowW
1 Mon 1 TRUE
2 Tue 2 TRUE
3 Wed 3 TRUE
4 Thu 4 TRUE
5 Fri 5 TRUE
A regular list is excellent for holding diverse kinds of data, for example 10
lm() objects, or a series of data frames.
In a list, the third element of component 1 may not have anything whatsoever
to do with the third element of component 2.
In a data frame, rows are related.
> If I were to hold recurring (Name, Salary, DateOfBirth) (i.e. character,
> integer and date values) in a list object, what would be the 'optimal'
> arrangement?
Data frame.
> Would that be as the components of weekProfile above? Or will this be better.
>
> Either:
>
> personalDetail<-
> list(rbind(c(Name,Salary,DateOfBirth),c(Name,Salary,DateOfBirth)));
--
Sarah Goslee
http://www.functionaldiversity.org
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