[R] data frame transformation

[Bert Gunter]

... and my reordering of column indices was unnecessary:
    merge(dat, d, all.y = TRUE)
will do.

Bert Gunter

"The trouble with having an open mind is that people keep coming along and
sticking things into it."
-- Opus (aka Berkeley Breathed in his "Bloom County" comic strip )


On Sun, Jan 6, 2019 at 5:16 AM Andras Farkas via R-help <
r-help using r-project.org> wrote:

> Hello Everyone,
>
> would you be able to assist with some expertise on how to get the
> following done in a way that can be applied to a data set with different
> dimensions and without all the line items here?
>
> we have:
>
> id<-c(1,1,1,2,2,2,2,3,3,4,4,4,4,5,5,5,5)#length of unique IDs may differ
> of course in real data set, usually in magnitude of 10000
>
> letter<-c(sample(c("A","B","C","D","E"),3),sample(c("A","B","C","D","E"),4),sample(c("A","B","C","D","E"),2),
>
> sample(c("A","B","C","D","E"),4),sample(c("A","B","C","D","E"),4))#number
> of unique "letters" is less than 4000 in real data set and they are no
> duplicates within same ID
> weight<-c(sample(c(1:30),3),sample(c(1:30),4),sample(c(1:30),2),
>           sample(c(1:30),4),sample(c(1:30),4))#number of unique weights is
> below 50 in real data set and they are no duplicates within same ID
>
>
> data<-data.frame(id=id,letter=letter,weight=weight)
>
> #goal is to get the following transformation where a column is added for
> each unique letter and the weight is pulled into the column if the letter
> exist within the ID, otherwise NA
> #so we would get datatransform like below but without the many steps
> described here
>
> datatransfer<-data.frame(data,apply(data[2],2,function(x)
> ifelse(x=="A",data$weight,NA)))
> datatransfer<-data.frame(datatransfer,apply(datatransfer[2],2,function(x)
> ifelse(x=="B",data$weight,NA)))
> datatransfer<-data.frame(datatransfer,apply(datatransfer[2],2,function(x)
> ifelse(x=="C",data$weight,NA)))
> datatransfer<-data.frame(datatransfer,apply(datatransfer[2],2,function(x)
> ifelse(x=="D",data$weight,NA)))
> datatransfer<-data.frame(datatransfer,apply(datatransfer[2],2,function(x)
> ifelse(x=="E",data$weight,NA)))
>
> colnames(datatransfer)<-c("id","weight","letter","A","B","C","D","E")
> much appreciate the help,
>
> thanks
>
> Andras
>
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