This is a compatibility release with dplyr 0.6.0.
dmap(), dmap_at(), dmap_if(), invoke_rows(), slice_rows(), map_rows(), by_slice(), by_row(), and unslice() have been moved to purrrlyr. This is a bit of an aggresive change but it allows us to make the dependencies much lighter.Fix for dev tibble support.
as_function() now supports list arguments which allow recursive indexing using either names or positions. They now always stop when encountering the first NULL (#173).
accumulate and reduce correctly pass extra arguments to the worker function.
as_function() gains a .null argument that for character and numeric values allows you to specify what to return for null/absent elements (#110). This can be used with any map function, e.g. map_int(x, 1, .null = NA)
as_function() is now generic.
New is_function() that returns TRUE only for regular functions.
Fix crash on GCC triggered by invoke_rows().
There are two handy infix functions:
x %||% y is shorthand for if (is.null(x)) y else x (#109).x %@% "a" is shorthand for attr(x, "a", exact = TRUE) (#69).accumulate() has been added to handle recursive folding. It is shortand for Reduce(f, .x, accumulate = TRUE) and follows a similar syntax to reduce() (#145). A right-hand version accumulate_right() was also added.
map_df() row-binds output together. It's the equivalent of plyr::ldply() (#127)
flatten() is now type-stable and always returns a list. To return a simpler vector, use flatten_lgl(), flatten_int(), flatten_dbl(), flatten_chr(), or flatten_df().
invoke() has been overhauled to be more useful: it now works similarly to map_call() when .x is NULL, and hence map_call() has been deprecated. invoke_map() is a vectorised complement to invoke() (#125), and comes with typed variants invoke_map_lgl(), invoke_map_int(), invoke_map_dbl(), invoke_map_chr(), and invoke_map_df().
transpose() replaces zip2(), zip3(), and zip_n() (#128). The name more clearly reflects the intent (transposing the first and second levels of list). It no longer has fields argument or the .simplify argument; instead use the new simplify_all() function.
safely(), quietly(), and possibly() are experimental functions for working with functions with side-effects (e.g. printed output, messages, warnings, and errors) (#120). safely() is a version of try() that modifies a function (rather than an expression), and always returns a list with two components, result and error.
list_along() and rep_along() generalise the idea of seq_along(). (#122).
is_null() is the snake-case version of is.null().
pmap() (parallel map) replaces map_n() (#132), and has typed-variants suffixed pmap_lgl(), pmap_int(), pmap_dbl(), pmap_chr(), and pmap_df().
set_names() is a snake-case alternative to setNames() with stricter equality checking, and more convenient defaults for pipes: x %>% set_names() is equivalent to setNames(x, x) (#119).
We are still figuring out what belongs in dplyr and what belongs in purrr. Expect much experimentation and many changes with these functions.
map() now always returns a list. Data frame support has been moved to map_df() and dmap(). The latter supports sliced data frames as a shortcut for the combination of by_slice() and dmap(): x %>% by_slice(dmap, fun, .collate = "rows"). The conditional variants dmap_at() and dmap_if() also support sliced data frames and will recycle scalar results to the slice size.
map_rows() has been renamed to invoke_rows(). As other rows-based functionals, it collates results inside lists by default, but with column collation this function is equivalent to plyr::mdply().
The rows-based functionals gain a .to option to name the output column as well as a .collate argument. The latter allows to collate the output in lists (by default), on columns or on rows. This makes these functions more flexible and more predictable.
as_function(), which converts formulas etc to functions, is now exported (#123).
rerun() is correctly scoped (#95)
update_list() can now modify an element called x (#98).
map*() now use custom C code, rather than relying on lapply(), mapply() etc. The performance characteristcs are very similar, but it allows us greater control over the output (#118).
map_lgl() now has second argument .f, not .p (#134).
flatmap() -> use map() followed by the appropriate flatten().
map_call() -> invoke().
map_n() -> pmap(); walk_n() -> pwalk().
map3(x, y, z) -> map_n(list(x, y, z)); walk3(x, y, z) ->pwalk(list(x, y, z))`