[R] How to avoid two for loops?

PIKAL Petr petr.pikal at precheza.cz
Wed Feb 25 17:36:49 CET 2015


Hi

It seems to me that it is work for aggregate. Your code is not reproducible so we cannot test it.

> temp<-read.table("clipboard", header=T)
> temp
  Country Product Brand Year_Month DisplaySize OperationSystem
1      AE       1    20     201204           1               1
2      AE       5    20     201204           1               1
3      AE       2    28     201204           3               2
4      AE       3    27     201204           1               1
5      AE       1    20     201205           1               1
6      AE       2    28     201205           3               2
7      AE       4    20     201205           1               2
> aggregate(temp$DisplaySize, list(temp$Brand), sum)
  Group.1 x
1      20 4
2      27 1
3      28 6

> aggregate(temp$DisplaySize, list(temp$Brand, temp$Year_Month), sum)
  Group.1 Group.2 x
1      20  201204 2
2      27  201204 1
3      28  201204 3
4      20  201205 2
5      28  201205 3

More flexible but more complicated is plyr package, which could probably be used too.

Cheers
Petr

> -----Original Message-----
> From: R-help [mailto:r-help-bounces at r-project.org] On Behalf Of conglan
> Sent: Wednesday, February 25, 2015 10:09 AM
> To: r-help at r-project.org
> Subject: [R] How to avoid two for loops?
>
> HI,
>
> I have the following large data set:
> the sample is as the following:
>   Country  Product   Brand  Year_Month   DisplaySize   OperationSystem
>      AE         1           20    201204              1
> 1
>      AE         5           20    201204              1
> 1
>      AE         2           28    201204              3
> 2
>      AE         3           27    201204              1
> 1
>      AE         1           20    201205              1
> 1
>      AE         2           28    201205              3
> 2
>      AE         4           20    201205              1
> 2
>
> I want to calculate the extra three columns as the following:
> Let's say "20" is own brand
>  #The sums of display size produced by competing brand
>  #The sums of display size of other products produced by own brand
>  #The sums of display size of products of competing firm in the same
> operating system
>
> I build up the following codes, apprently two loop takes too long time:
>
> dd<-unique(cl$Year_Month)
>
> fldata<-data.frame(NULL)
>
> for ( i in 1:length(dd)){
>
>   cls<-cl[cl$Year_Month==dd[i],]
>   ws<-numeric(0)  #The sums of characteristics of products produced by
> competing firms
>   ws1<-numeric(0)  #The sums of characteristics of other products
> produced
> by firm
>   ws2<-numeric(0) #The sums of characteristics of products of competing
> firm in the same operating system
>
>
>   for (j in 1:dim(cls)[1]){
>
>    wd<-sum(cls[cls$Brand!=cls$Brand[j],]$DISPLAY_SIZE_INCH)
>    ws[j]<-wd
>    wc<-sum(cls[cls$Brand==cls$Brand[j] & cls$Item_Id!=cls$Item_Id[j]
> ,]$DISPLAY_SIZE_INCH)
>    ws1[j]<-wc
>    wf<-sum(cls[cls$Brand!=cls$Brand[j] &
> cls$OPERATING_SYST==cls$OPERATING_SYST[j]
> ,]$DISPLAY_SIZE_INCH)
>    ws2[j]<-wf
>    }
>
>   cls<-cbind(cls,SumPCf=ws,SumOPf=ws1,SumPCfOp=ws2)
>   fldata<-rbind(fldata,cls)
>
> }
>
>
> how can I avoid two loops and improve the speed of my code??????? any
> other
> solution?
>
>
> Thanks.
>
> Tammy
>
>
>
>
> --
> View this message in context: http://r.789695.n4.nabble.com/How-to-
> avoid-two-for-loops-tp4703799.html
> Sent from the R help mailing list archive at Nabble.com.
>       [[alternative HTML version deleted]]
>
> ______________________________________________
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> and provide commented, minimal, self-contained, reproducible code.

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