making chains from pairs

Hello,

having a data frame like test with pairs of characters I would like to
create chains. For instance from the pairs A/B and B/I you get the vector A
B I. It is like jumping from one pair to the next related pair. So for my
example test you should get:
A B F G H I
C F I K
D L M N O P
second <- with(test, tapply(V2, V1, FUN=function(x) test[test$V2==x, ] ) )
Warning messages:
1: In test$V2 == x :
  longer object length is not a multiple of shorter object length
2: In test$V2 == x :
  longer object length is not a multiple of shorter object length
3: In test$V2 == x :
  longer object length is not a multiple of shorter object length
third <- sapply(names(second) , function(df) c(df, second[[df]][ , "V2" ]) )
third
$A
[1] "A" "B" "F" "G" "H"

$B
[1] "B" "F" "I" "F" "I"

$C
[1] "C" "F" "I" "K"

$D
[1] "D" "L" "M" "N"

$L
[1] "L" "O" "P"
fourth <- sapply(names(third), function(d) unique( c(third[[d]], 
unlist(third[ sapply( third[[d]], "[" ) ]) ) ) )
fourth
$A
[1] "A" "B" "F" "G" "H" "I"

$B
[1] "B" "F" "I"

$C
[1] "C" "F" "I" "K"

$D
[1] "D" "L" "M" "N" "O" "P"

$L
[1] "L" "O" "P"

test
  V1 V2
1   A  B
2   A  F
3   A  G
4   A  H
5   B  F
6   B  I
7   C  F
8   C  I
9   C  K
10  D  L
11  D  M
12  D  N
13  L  O
14  L  P

Thanks
Hermann

dput (test)
structure(list(V1 = c("A", "A", "A", "A", "B", "B", "C", "C",
"C", "D", "D", "D", "L", "L"), V2 = c("B", "F", "G", "H", "F",
"I", "F", "I", "K", "L", "M", "N", "O", "P")), .Names = c("V1",
"V2"), row.names = c(NA, -14L), class = "data.frame")

	[[alternative HTML version deleted]]

______________________________________________
R-help at r-project.org mailing list
https://stat.ethz.ch/mailman/listinfo/r-help
PLEASE do read the posting guide http://www.R-project.org/posting-guide.html
and provide commented, minimal, self-contained, reproducible code.
David Winsemius
Alameda, CA, USA

making chains from pairs

Thread (3 messages)