# tidyr 1.2.0
## Pivoting
* `pivot_wider()` gains new `names_expand` and `id_expand` arguments for turning
implicit missing factor levels and variable combinations into explicit ones.
This is similar to the `drop` argument from `spread()` (#770).
* `pivot_wider()` gains a new `names_vary` argument for controlling the
ordering when combining `names_from` values with `values_from` column names
(#839).
* `pivot_wider()` gains a new `unused_fn` argument for controlling how to
summarize unused columns that aren't involved in the pivoting process (#990,
thanks to @mgirlich for an initial implementation).
* `pivot_longer()`'s `names_transform` and `values_transform` arguments now
accept a single function which will be applied to all of the columns
(#1284, thanks to @smingerson for an initial implementation).
* `pivot_longer()`'s `names_ptypes` and `values_ptypes` arguments now
accept a single empty ptype which will be applied to all of the columns
(#1284).
## Nesting
* `unnest()` and `unchop()`'s `ptype` argument now accepts a single empty
ptype which will be applied to all `cols` (#1284).
* `unpack()` now silently skips over any non-data frame columns specified by
`cols`. This matches the existing behavior of `unchop()` and `unnest()`
(#1153).
## Rectangling
* `unnest_wider()` and `unnest_longer()` can now unnest multiple columns at
once (#740).
* `unnest_longer()`'s `indices_to` and `values_to` arguments now accept
a glue specification, which is useful when unnesting multiple columns.
* For `hoist()`, `unnest_longer()`, and `unnest_wider()`, if a `ptype` is
supplied, but that column can't be simplified, the result will be a list-of
column where each element has type `ptype` (#998).
* `unnest_wider()` gains a new `strict` argument which controls whether or not
strict vctrs typing rules should be applied. It defaults to `FALSE` for
backwards compatibility, and because it is often more useful to be lax
when unnesting JSON, which doesn't always map one-to-one with R's types
(#1125).
* `hoist()`, `unnest_longer()`, and `unnest_wider()`'s `simplify` argument now
accepts a named list of `TRUE` or `FALSE` to control simplification on a per
column basis (#995).
* `hoist()`, `unnest_longer()`, and `unnest_wider()`'s `transform` argument now
accepts a single function which will be applied to all components (#1284).
* `hoist()`, `unnest_longer()`, and `unnest_wider()`'s `ptype` argument now
accepts a single empty ptype which will be applied to all components (#1284).
## Grids
* `complete()` gains a new `explicit` argument for limiting `fill` to only
implicit missing values. This is useful if you don't want to fill in
pre-existing missing values (#1270).
* `complete()` gains a grouped data frame method. This generates a more correct
completed data frame when groups are involved (#396, #966).
* `complete()` and `expand()` no longer allow you to complete or expand on a
grouping column. This was never well-defined since completion/expansion on a
grouped data frame happens "within" each group and otherwise has the
potential to produce erroneous results (#1299).
## Missing values
* `drop_na()`, `replace_na()`, and `fill()` have been updated to utilize vctrs.
This means that you can use these functions on a wider variety of column
types, including lubridate's Period types (#1094), data frame columns, and
the [rcrd](https://vctrs.r-lib.org/reference/new_rcrd.html) type from vctrs.
* `replace_na()` no longer allows the type of `data` to change when the
replacement is applied. `replace` will now always be cast to the type of
`data` before the replacement is made. For example, this means that using a
replacement value of `1.5` on an integer column is no longer allowed.
Similarly, replacing missing values in a list-column must now be done with
`list("foo")` rather than just `"foo"`.
* `replace_na()` no longer replaces empty atomic elements in list-columns
(like `integer(0)`). The only value that is replaced in a list-column is
`NULL` (#1168).
* `drop_na()` no longer drops empty atomic elements from list-columns
(like `integer(0)`). The only value that is dropped in a list-column is
`NULL` (#1228).
## Bug fixes and minor improvements
### General
* @mgirlich is now a tidyr author in recognition of his significant and
sustained contributions.
* All lazyeval variants of tidyr verbs have been soft-deprecated. Expect them
to move to the defunct stage in the next minor release of tidyr (#1294).
* `any_of()` and `all_of()` from tidyselect are now re-exported (#1217).
* dplyr >= 1.0.0 is now required.
### Pivoting
* `pivot_wider()` now gives better advice about how to identify duplicates when
values are not uniquely identified (#1113).
* `pivot_wider()` now throws a more informative error when `values_fn` doesn't
result in a single summary value (#1238).
* `pivot_wider()` and `pivot_longer()` now generate more informative
errors related to name repair (#987).
* `pivot_wider()` now works correctly when `values_fill` is a data frame.
* `pivot_wider()` no longer accidentally retains `values_from` when pivoting
a zero row data frame (#1249).
* `pivot_wider()` now correctly handles the case where an id column name
collides with a value from `names_from` (#1107).
* `pivot_wider()` and `pivot_longer()` now both check that the spec columns
`.name` and `.value` are character vectors. Additionally, the `.name`
column must be unique (#1107).
* `pivot_wider()`'s `names_from` and `values_from` arguments are now
required if their default values of `name` and `value` don't correspond to
columns in `data`. Additionally, they must identify at least 1 column
in `data` (#1240).
* `pivot_wider()`'s `values_fn` argument now correctly allows anonymous
functions (#1114).
* `pivot_wider_spec()` now works correctly with a 0-row data frame and a `spec`
that doesn't identify any rows (#1250, #1252).
* `pivot_longer()`'s `names_ptypes` argument is now applied after
`names_transform` for consistency with the rectangling functions
(i.e. `hoist()`) (#1233).
* `check_pivot_spec()` is a new developer facing function for validating a pivot
`spec` argument. This is only useful if you are extending `pivot_longer()` or
`pivot_wider()` with new S3 methods (#1087).
### Nesting
* The `nest()` generic now avoids computing on `.data`, making it more
compatible with lazy tibbles (#1134).
* The `.names_sep` argument of the data.frame method for `nest()` is now
actually used (#1174).
* `unnest()`'s `ptype` argument now works as expected (#1158).
* `unpack()` no longer drops empty columns specified through `cols` (#1191).
* `unpack()` now works correctly with data frame columns containing 1 row but
0 columns (#1189).
* `chop()` now works correctly with data frames with 0 rows (#1206).
* `chop()`'s `cols` argument is no longer optional. This matches the
behavior of `cols` seen elsewhere in tidyr (#1205).
* `unchop()` now respects `ptype` when unnesting a non-list column (#1211).
### Rectangling
* `hoist()` no longer accidentally removes elements that have duplicated names
(#1259).
### Grids
* The grouped data frame methods for `complete()` and `expand()` now move the
group columns to the front of the result (in addition to the columns you
completed on or expanded, which were already moved to the front). This should
make more intuitive sense, as you are completing or expanding "within" each
group, so the group columns should be the first thing you see (#1289).
* `complete()` now applies `fill` even when no columns to complete are
specified (#1272).
* `expand()`, `crossing()`, and `nesting()` now correctly retain `NA` values of
factors (#1275).
* `expand_grid()`, `expand()`, `nesting()`, and `crossing()` now silently
apply name repair to automatically named inputs. This avoids a number of
issues resulting from duplicate truncated names
(#1116, #1221, #1092, #1037, #992).
* `expand_grid()`, `expand()`, `nesting()`, and `crossing()` now allow
columns from unnamed data frames to be used in expressions after that
data frame was specified, like `expand_grid(tibble(x = 1), y = x)`. This
is more consistent with how `tibble()` behaves.
* `expand_grid()`, `expand()`, `nesting()`, and `crossing()` now work
correctly with data frames containing 0 columns but >0 rows (#1189).
* `expand_grid()`, `expand()`, `nesting()`, and `crossing()` now return a 1
row data frame when no inputs are supplied, which is more consistent with
`prod() == 1L` and the idea that computations involving the number of
combinations computed from an empty set should return 1 (#1258).
### Missing values
* `drop_na()` no longer drops missing values from all columns when a tidyselect
expression that results in 0 columns being selected is used (#1227).
* `fill()` now treats `NaN` like any other missing value (#982).
# tidyr 1.1.4
* `expand_grid()` is now about twice as fast and `pivot_wider()` is a bit faster
(@mgirlich, #1130).
* `unchop()` is now much faster, which propagates through to various functions,
such as `unnest()`, `unnest_longer()`, `unnest_wider()`, and
`separate_rows()` (@mgirlich, @DavisVaughan, #1127).
* `unnest()` is now much faster (@mgirlich, @DavisVaughan, #1127).
* `unnest()` no longer allows unnesting a list-col containing a mix of vector
and data frame elements. Previously, this only worked by accident, and is
considered an off-label usage of `unnest()` that has now become an error.
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