Transpose a list.
Transpose turns a list-of-lists "inside-out"; it turns a pair of lists into a
list of pairs, or a list of pairs into pair of lists. For example,
if you had a list of length n where each component had values a and
b, transpose() would make a list with elements a and
b that contained lists of length n. It's called transpose because
x[[1]][[2]] is equivalent to transpose(x)[[2]][[1]].
transpose(.l, .names = NULL)
.l |
A list of vectors to transpose. The first element is used as the template; you'll get a warning if a subsequent element has a different length. |
.names |
For efficiency, |
Note that transpose() is its own inverse, much like the
transpose operation on a matrix. You can get back the original
input by transposing it twice.
A list with indexing transposed compared to .l.
x <- rerun(5, x = runif(1), y = runif(5))
x %>% str()
x %>% transpose() %>% str()
# Back to where we started
x %>% transpose() %>% transpose() %>% str()
# transpose() is useful in conjunction with safely() & quietly()
x <- list("a", 1, 2)
y <- x %>% map(safely(log))
y %>% str()
y %>% transpose() %>% str()
# Use simplify_all() to reduce to atomic vectors where possible
x <- list(list(a = 1, b = 2), list(a = 3, b = 4), list(a = 5, b = 6))
x %>% transpose()
x %>% transpose() %>% simplify_all()
# Provide explicit component names to prevent loss of those that don't
# appear in first component
ll <- list(
list(x = 1, y = "one"),
list(z = "deux", x = 2)
)
ll %>% transpose()
nms <- ll %>% map(names) %>% reduce(union)
ll %>% transpose(.names = nms)Please choose more modern alternatives, such as Google Chrome or Mozilla Firefox.