output a llst of vectors from a two column data frame-CodePudding

I am trying to convert a data frame:

df <- data.frame(id=c(1,1,1,2,2), code=c("a","b","c","a","b"))

to this output list where the name of each list contains the row id.

a_list <- list(
  Tr1 = c("a","b","c"),
  Tr2 = c("a","b")
)

Thank you!

CodePudding user response：

if not interested in names:

unstack(df, code~id)
$`1`
[1] "a" "b" "c"

$`2`
[1] "a" "b

or even:

 unstack(rev(df))
$`1`
[1] "a" "b" "c"

$`2`
[1] "a" "b"

with(df, split(code, id))
$`1`
[1] "a" "b" "c"

$`2`
[1] "a" "b"

if interested in names:

  unstack(transform(df, id=paste0('Tr', id)), code~id)
$Tr1
[1] "a" "b" "c"

$Tr2
[1] "a" "b"

or even:

with(df, split(code, paste0('Tr', id)))
$Tr1
[1] "a" "b" "c"

$Tr2
[1] "a" "b"

CodePudding user response：

You can use split, i.e.

l1 <- split(df$code, df$id)
setNames(l1, paste0('Tr', seq_along(l1)))

$Tr1
[1] "a" "b" "c"

$Tr2
[1] "a" "b"