CODEWITHSUNDEEP
rtidyr
jackonator
jackonator

Reputation: 33

R: Tidy row for each comparison pair

I would like to gather the rows for each pair of comparison. In other words, go from:

x=data.frame(id="Study1",
       t1=1,
       t2=2,
       t3=3,
       y2=0.1,
       y3=0.2,
       se2=0.5,
       se3=0.7)

to:

y=data.frame(id=c("Study1", "Study1"),
         t1=c(1,1),
         t2=c(2,3),
         y2=c(0.1,0.2),
         se2=c(0.5,0.7))

Upvotes: 0

Views: 48

Answers (2)

MKR
MKR

Reputation: 20085

An option is to use grouped measure variables of data.table::melt as:

library(data.table)


melt(setDT(x), id=1:2, measure=list(c("t2","t3"), c("y2","y3"), c("se2","se3")), 
                                  value.name=c("t2", "y2", "se2"))

#Or in short form
melt(setDT(x), id=1:2, measure=patterns("^t[2-3]", "^y", "^se"),
                       value.name=c("t2", "y2", "se2"))
#        id t1 variable t2  y2 se2
# 1: Study1  1        1  2 0.1 0.5
# 2: Study1  1        2  3 0.2 0.7

Upvotes: 0

Onyambu
Onyambu

Reputation: 79208

You can use reshape 

n=length(grep("y",names(x)))
reshape(x,t(matrix(3:ncol(x),n)),idvar="id",dir="long")  
             id t1 time t2  y2 se2
Study1.1 Study1  1    1  2 0.1 0.5
Study1.2 Study1  1    2  3 0.2 0.7

or you can use:

library(data.table)
cbind(melt(setDT(x),"id",data.frame(matrix(3:ncol(x),2)),t1=x$t1)
           id variable value1 value2 value3 t1
    1: Study1        1      2    0.1    0.5  1
    2: Study1        2      3    0.2    0.7  1   


reshape(x,data.frame(matrix(3:ncol(x),2)),idvar="id",dir="long")
          id t1 time t2  y2 se2
    1 Study1  1    1  2 0.1 0.5
    2 Study1  1    2  3 0.2 0.7

Upvotes: 1

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