[R] Data indexing issue...

[jim holtman]

Why not use 'split' and get all the groups at once:

result <- split(Calandra, list(Calandra$Day, Calandra$Season, drop = TRUE)

On Tue, Mar 27, 2012 at 7:43 AM, Ivan Calandra
<ivan.calandra at u-bourgogne.fr> wrote:
> Hi HJ,
>
> Take a look at ?"&"; this is probably what you're looking for.
>
> What you could also do is:
> Calender[Calender$Day=='Wd' & Calender$Season=="Winter", ]  # notice the
> last comma
>
> This will subset directly without using which(); it might be helpful to you.
>
> HTH,
> Ivan
>
> --
> Ivan CALANDRA
> Université de Bourgogne
> UMR CNRS/uB 6282 Biogéosciences
> 6 Boulevard Gabriel
> 21000 Dijon, FRANCE
> +33(0)3.80.39.63.06
> ivan.calandra at u-bourgogne.fr
> http://biogeosciences.u-bourgogne.fr/calandra
>
>
> Le 27/03/12 12:32, HJ YAN a écrit :
>
>> Dear R-help,
>>
>> My dataset (which is a data frame, called 'Calender' here)  includes 365
>> rows representing 365 days for a year.  One column ('Season')contains
>> factor data representing seasons, e.g. spring, summer, autumn and winter.
>> Another column (called 'Day') contains data representing wether the day
>>  is
>> a working day  (I use 'Wd' for short here)or weekend (I use 'Wkend' for
>> short here).
>>
>>
>> I want to seperate the index of the working days  and weekends for each
>> season. I used R commend "which" before for one criteria, for example, if
>> I
>> use...
>>
>>
>> WdIndex<-which(Calender$Day=='Wd')
>>
>> that will gives a set of indeices of working days in the year.
>>
>> I wonder in R could I use a combination of something such as 'AND' , 'OR'
>> (e.g. in MySQL) to set 'multi-criteria'  when selecting data. So for
>> example...
>>
>> WinterWdIndex<-which(Calender$Day=='Wd' AND Calender$Season=="Winter")
>>
>>
>> I know the above syntax is wrong, and I checked '?which' which did not
>> give
>> me an answer and also tried '?AND' but seems it doesn`t exist at all...
>>
>>
>> Many thanks!
>> HJ
>>
>>        [[alternative HTML version deleted]]
>>
>> ______________________________________________
>> R-help at r-project.org 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.
>>
>>
>
> ______________________________________________
> R-help at r-project.org 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.



-- 
Jim Holtman
Data Munger Guru

What is the problem that you are trying to solve?
Tell me what you want to do, not how you want to do it.