[R] data frame transformation

[K. Elo]

Hi!

Maybe this would do the trick:

--- snip ---

library(reshape2) # Use 'reshape2'
library(dplyr)    # Use 'dplyr'

datatransfer<-data %>% mutate(letter2=letter) %>% 
  dcast(id+letter~letter2, value.var="weight")

--- snip ---

Or did I misunderstood something?

Best,

Kimmo

2019-01-06, 13:16 +0000, Andras Farkas via R-help 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),s
> ample(c("A","B","C","D","E"),2),
>          
> sample(c("A","B","C","D","E"),4),sample(c("A","B","C","D","E"),4))#nu
> mber 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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