tidyr 0.6.2

• Register C functions

• Added package docs

• Patch tests to be compatible with dev dplyr.

tidyr 0.6.1

• Patch test to be compatible with dev tibble
• Changed deprecation message of extract_numeric() to point to
  readr::parse_number() rather than readr::parse_numeric()

tidyr 0.6.0

API changes

• drop_na() removes observations which have NA in the given variables. If no
  variables are given, all variables are considered (#194, @JanSchulz).
• extract_numeric() has been deprecated (#213).
• Renamed table4 and table5 to table4a and table4b to make their
  connection more clear. The key and value variables in table2 have
  been renamed to type and count.

Bug fixes and minor improvements

• expand(), crossing(), and nesting() now silently drop zero-length
  inputs.
• crossing_() and nesting_() are versions of crossing() and nesting()
  that take a list as input.
• full_seq() works correctly for dates and date/times.

tidyr 0.5.1

• Restored compatibility with R < 3.3.0 by avoiding getS3method(envir = ) (#205, @krlmlr).

tidyr 0.5.0

New functions

• separate_rows() separates observations with multiple delimited values into
  separate rows (#69, @aaronwolen).

Bug fixes and minor improvements

• complete() preserves grouping created by dplyr (#168).
• expand() (and hence complete()) preserves the ordered attribute of
  factors (#165).
• full_seq() preserve attributes for dates and date/times (#156),
  and sequences no longer need to start at 0.
• gather() can now gather together list columns (#175), and
  gather_.data.frame(na.rm = TRUE) now only removes missing values
  if they're actually present (#173).
• nest() returns correct output if every variable is nested (#186).
• separate() fills from right-to-left (not left-to-right!) when fill = "left"
  (#170, @dgrtwo).
• separate() and unite() now automatically drop removed variables from
  grouping (#159, #177).
• spread() gains a sep argument. If not-null, this will name columns
  as "keyvalue". Additionally, if sep is NULL missing values will be
  converted to <NA> (#68).
• spread() works in the presence of list-columns (#199)
• unnest() works with non-syntactic names (#190).
• unnest() gains a sep argument. If non-null, this will rename the
  columns of nested data frames to include both the original column name,
  and the nested column name, separated by .sep (#184).
• unnest() gains .id argument that works the same way as bind_rows().
  This is useful if you have a named list of data frames or vectors (#125).
• Moved in useful sample datasets from the DSR package.
• Made compatible with both dplyr 0.4 and 0.5.
• tidyr functions that create new columns are more aggresive about re-encoding
  the column names as UTF-8.

tidyr 0.4.1

• Fixed bug in nest() where nested data was ending up in the wrong row (#158).

tidyr 0.4.0

Nested data frames

nest() and unnest() have been overhauled to support a useful way of structuring data frames: the nested data frame. In a grouped data frame, you have one row per observation, and additional metadata define the groups. In a nested data frame, you have one row per group, and the individual observations are stored in a column that is a list of data frames. This is a useful structure when you have lists of other objects (like models) with one element per group.

• nest() now produces a single list of data frames called "data" rather
  than a list column for each variable. Nesting variables are not included
  in nested data frames. It also works with grouped data frames made
  by dplyr::group_by(). You can override the default column name with .key.
• unnest() gains a .drop argument which controls what happens to
  other list columns. By default, they're kept if the output doesn't require
  row duplication; otherwise they're dropped.
• unnest() now has mutate() semantics for ... - this allows you to
  unnest transformed columns more easily. (Previously it used select semantics).

Expanding

• expand() once again allows you to evaluate arbitrary expressions like
  full_seq(year). If you were previously using c() to created nested
  combinations, you'll now need to use nesting() (#85, #121).
• nesting() and crossing() allow you to create nested and crossed data
  frames from individual vectors. crossing() is similar to
  base::expand.grid()
• full_seq(x, period) creates the full sequence of values from min(x) to
  max(x) every period values.

Minor bug fixes and improvements

• fill() fills in NULLs in list-columns.
• fill() gains a direction argument so that it can fill either upwards or
  downwards (#114).
• gather() now stores the key column as character, by default. To revert to
  the previous behaviour of using a factor (which allows you to preserve the
  ordering of the columns), use key_factor = TRUE (#96).
• All tidyr verbs do the right thing for grouped data frames created by
  group_by() (#122, #129, #81).
• seq_range() has been removed. It was never used or announced.
• spread() once again creates columns of mixed type when convert = TRUE
  (#118, @jennybc). spread() with drop = FALSE handles zero-length
  factors (#56). spread()ing a data frame with only key and value columns
  creates a one row output (#41).
• unite() now removes old columns before adding new (#89, @krlmlr).
• separate() now warns if defunct ... argument is used (#151, @krlmlr).

tidyr 0.3.1

• Fixed bug where attributes of non-gather columns were lost (#104)

tidyr 0.3.0

New features

• New complete() provides a wrapper around expand(), left_join() and
  replace_na() for a common task: completing a data frame with missing
  combinations of variables.
• fill() fills in missing values in a column with the last non-missing
  value (#4).
• New replace_na() makes it easy to replace missing values with something
  meaningful for your data.
• nest() is the complement of unnest() (#3).
• unnest() can now work with multiple list-columns at the same time.
  If you don't supply any columns names, it will unlist all
  list-columns (#44). unnest() can also handle columns that are
  lists of data frames (#58).

Bug fixes and minor improvements

• tidyr no longer depends on reshape2. This should fix issues if you also
  try to load reshape (#88).
• %>% is re-exported from magrittr.
• expand() now works with non-standard column names (#87).
• expand() now supports nesting and crossing (see examples for details).
  This comes at the expense of creating new variables inline (#46).
• expand_ does SE evaluation correctly so you can pass it a character vector
  of columns names (or list of formulas etc) (#70).
• extract() is 10x faster because it now uses stringi instead of
  base R regular expressions. It also returns NA instead of throwing
  an error if the regular expression doesn't match (#72).
• extract() and separate() preserve character vectors when
  covert is TRUE (#99).
• The internals of spread() have been rewritten, and now preserve all
  attributes of the input value column. This means that you can now
  spread date (#62) and factor (#35) inputs.
• spread() gives a more informative error message if key or value don't
  exist in the input data (#36).
• separate() only displays the first 20 failures (#50). It has
  finer control over what happens if there are two few matches:
  you can fill with missing values on either the "left" or the "right" (#49).
  separate() no longer throws an error if the number of pieces aren't
  as expected - instead it uses drops extra values and fills on the right
  and gives a warning.
• If the input is NA separate() and extract() both return silently
  return NA outputs, rather than throwing an error. (#77)
• Experimental unnest() method for lists has been removed.

tidyr 0.2.0

New functions

• Experimental expand() function (#21).
• Experiment unnest() function for converting named lists into
  data frames. (#3, #22)

Bug fixes and minor improvements

• extract_numeric() preserves negative signs (#20).
• gather() has better defaults if key and value are not supplied.
  If ... is ommitted, gather() selects all columns (#28). Performance
  is now comparable to reshape2::melt() (#18).
• separate() gains extra argument which lets you control what happens
  to extra pieces. The default is to throw an "error", but you can also
  "merge" or "drop".
• spread() gains drop argument, which allows you to preserve missing
  factor levels (#25). It converts factor value variables to character vectors,
  instead of embedding a matrix inside the data frame (#35).