[R] appending data to a row

[arun]

HI,
May be this helps:
(assuming that there are only twins)

dat1<- read.table(text="
FamilyID  ParticipantID  IQ  Digit_span
1            1          95  6
1            2          93  7
2            3          102 8
2            4          101 9
3            5          106 7
3            6          108 9
",sep="",header=TRUE)
 dat1$Co_twin_IQ<-NA
 dat1$Co_twin_Digit_span<-NA
 dat1[,5:6]<-do.call(rbind,lapply(split(dat1,dat1$FamilyID),function(x)x[2:1,3:4]))

dat1
#  FamilyID ParticipantID  IQ Digit_span Co_twin_IQ Co_twin_Digit_span
#1        1             1  95          6         93                  7
#2        1             2  93          7         95                  6
#3        2             3 102          8        101                  9
#4        2             4 101          9        102                  8
#5        3             5 106          7        108                  9
#6        3             6 108          9        106                  7


dat2<- read.table(text="
FamilyID  ParticipantID  IQ  Digit_span Co-twin_IQ Co-twin_Digit_span
1            1          95  6          93          7
1            2          93  7          95          6
2            3          102 8          101        9
2            4          101 9          102        8
3            5          106 7          108        9
3            6          108 9          106        7
",sep="",header=TRUE)
colnames(dat2)<- colnames(dat1)
 identical(dat1,dat2)
#[1] TRUE
A.K.




----- Original Message -----
From: Jamie <jms2cor4 at gmail.com>
To: r-help at r-project.org
Cc: 
Sent: Thursday, February 14, 2013 4:07 PM
Subject: [R] appending data to a row

For an analysis of data from twins, I'd like to do some rearranging in my
dataframe. Currently, each twin has his or her own row. I'd like to add
several columns of the co-twin's data to each row. In other words, this is
the current situation:

FamilyID  ParticipantID  IQ  Digit_span
1             1          95  6
1             2          93  7
2             3          102 8
2             4          101 9
3             5          106 7
3             6          108 9

And this is what I'd like to have, only with even more co-twin data:

FamilyID  ParticipantID  IQ  Digit_span Co-twin_IQ Co-twin_Digit_span
1             1          95  6          93          7
1             2          93  7          95          6
2             3          102 8          101         9
2             4          101 9          102         8
3             5          106 7          108         9
3             6          108 9          106         7

I'm not sure how to tell R to take the specified values from the other row
with the same family ID and append them with a new name. Thanks for any
ideas you can offer me.

Jamie in Illinois

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