forcats 0.5.2

New fct() which works like factor() but errors if values of x are not included in the levels specification (#299)
first2() and last2() now ignore missing values in both x and y (#303).
Error messages are more informative.

forcats 0.5.1

as_factor() gains a logical method that always returns a factor with levels “FALSE” and “TRUE” (#185).
fct_c(), fct_collapse() and fct_recode() are now explicitly documented as using dynamic dots (@labouz, #234).
fct_collapse() now accepts a other_level argument, to allow a user-specified Other level (@gtm19, #194). It now correctly collapses factors when other_level is not NULL (#172), and makes "Other" the last level (#202) (@gtm19, #172 & #202)
fct_count() no longer converts implicit NAs into explicit NAs (#151).
fct_inseq() behaves more robustly when factor levels aren’t all numbers (#221).
fct_lump() has been split up into three new functions: fct_lump_prop(), fct_lump_n(), and fct_lump_lowfreq(). (@jonocarroll, #167, #142). All fct_lump_() functions check their inputs more carefully (@robinson_es, #169)
fct_reorder2() gains a helper function first2(), that sorts .y by the first value of .x (@jtr13).

fct_collapse() gains a group_other argument to allow you to group all un-named levels into "Other". (#100, @AmeliaMN)
fct_cross() creates a new factor containing the combined levels from two or more input factors, similar to base::interaction (@tslumley, #136)
fct_inseq() reorders labels in numeric order, if possible (#145, @kbodwin).
fct_lump_min() preserves levels that appear at least min times (can also be used with the w weighted argument) (@robinsones, #142).
fct_match() performs validated matching, providing a safer alternative to f %in% c("x", "y") which silently returns FALSE if "x" or "y" are not levels of f (e.g. because of a typo) (#126, @jonocarroll).
fct_relevel() can now level factors using a function that is passed the current levels (#117).
as_factor() now has a numeric method. By default, orders factors in numeric order, unlike the other methods which default to order of appearance. (#145, @kbodwin)

fct_count() gains a parameter to also compute the proportion (@zhiiiyang, #146).
fct_lump() now does not change the label if no lumping occurs (@zhiiiyang, #130).
fct_relabel() now accepts character input.
fct_reorder() and fct_reorder2() no longer require that the summary function return a numeric vector of length 1; instead it can return any orderable vector of length 1 (#147).
fct_reorder(), fct_reorder2() and as_factor() now use the ellipsis package to warn if you pass in named components to ... (#174).

fct_c() now requires explicit splicing with !!! if you have a list of factors that you want to combine. This is consistent with an emerging standards for handling ... throughout the tidyverse.
fct_reorder() and fct_reorder2() have renamed fun to .fun to avoid spurious matching of named arguments.

All functions that take ... use “tidy” dots: this means that you use can !!! to splice in a list of values, and trailing empty arguments are automatically removed. Additionally, all other arguments gain a . prefix in order to avoid unhelpful matching of named arguments (#110).
fct_lump() gains w argument (#70, @wilkox) to weight value frequencies before lumping them together (#68).

Test coverage increased from 80% to 99%.
fct_drop() now preserves attributes (#83).
fct_expand() and lvls_expand() now also take character vectors (#99).
fct_relabel() now accepts objects coercible to functions by rlang::as_function (#91, @alistaire47)

as_factor() which works like as.factor() but orders levels by appearance to avoid differences between locales (#39).
fct_other() makes it easier to convert selected levels to “other” (#40)
fct_relabel() allows programmatic relabeling of levels (#50, @krlmlr).

fct_c() can take either a list of factors or individual factors (#42).
fct_drop() gains only argument to restrict which levels are dropped (#69) and no longer adds NA level if not present (#52).
fct_recode() is now checks that each new value is of length 1 (#56).
fct_relevel() gains after argument so you can also move levels to the end (or any other position you like) (#29).
lvls_reorder(), fct_inorder(), and fct_infreq() gain an ordered argument, allowing you to override the existing “ordered” status (#54).