Tools for Working with Categorical Variables (Factors)
Helpers for reordering factor levels (including
moving specified levels to front, ordering by first appearance,
reversing, and randomly shuffling), and tools for modifying factor
levels (including collapsing rare levels into other, 'anonymising',
and manually 'recoding').
R uses factors to handle categorical variables, variables that have a fixed and known set of possible values. Factors are also helpful for reordering character vectors to improve display. The goal of the forcats package is to provide a suite of tools that solve common problems with factors, including changing the order of levels or the values. Some examples include:
fct_reorder(): Reordering a factor by another variable.
fct_infreq(): Reordering a factor by the frequency of values.
fct_relevel(): Changing the order of a factor by hand.
fct_lump(): Collapsing the least/most frequent values of a factor into "other".
You can learn more about each of these in
vignette("forcats"). If you're new to factors, the best place to start is the chapter on factors in R for Data Science.
# The easiest way to get forcats is to install the whole tidyverse: install.packages("tidyverse") # Alternatively, install just forcats: install.packages("forcats") # Or the the development version from GitHub: # install.packages("devtools") devtools::install_github("tidyverse/forcats")
forcats is part of the core tidyverse, so you can load it with
library(forcats) library(dplyr) library(ggplot2)
starwars %>% filter(!is.na(species)) %>% count(species, sort = TRUE) #> # A tibble: 37 x 2 #> species n #> <chr> <int> #> 1 Human 35 #> 2 Droid 5 #> 3 Gungan 3 #> 4 Kaminoan 2 #> 5 Mirialan 2 #> 6 Twi'lek 2 #> 7 Wookiee 2 #> 8 Zabrak 2 #> 9 Aleena 1 #> 10 Besalisk 1 #> # … with 27 more rows
starwars %>% filter(!is.na(species)) %>% mutate(species = fct_lump(species, n = 3)) %>% count(species) #> # A tibble: 4 x 2 #> species n #> <fct> <int> #> 1 Droid 5 #> 2 Gungan 3 #> 3 Human 35 #> 4 Other 39
ggplot(starwars, aes(x = eye_color)) + geom_bar() + coord_flip()
starwars %>% mutate(eye_color = fct_infreq(eye_color)) %>% ggplot(aes(x = eye_color)) + geom_bar() + coord_flip()
For a history of factors, I recommend stringsAsFactors: An unauthorized biography by Roger Peng and stringsAsFactors = <sigh> by Thomas Lumley. If you want to learn more about other approaches to working with factors and categorical data, I recommend Wrangling categorical data in R, by Amelia McNamara and Nicholas Horton.
Code of Conduct
Please note that the 'forcats' project is released with a Contributor Code of Conduct. By contributing to this project, you agree to abide by its terms.
Functions in forcats
|as_factor||Convert input to a factor.|
|fct_anon||Anonymise factor levels|
|fct_count||Count entries in a factor|
|fct_other||Replace levels with "other"|
|fct_recode||Change factor levels by hand|
|fct_cross||Combine levels from two or more factors to create a new factor|
|fct_drop||Drop unused levels|
|fct_explicit_na||Make missing values explicit|
|fct_expand||Add additional levels to a factor|
|fct_shift||Shift factor levels to left or right, wrapping around at end|
|fct_shuffle||Randomly permute factor levels|
|fct_unify||Unify the levels in a list of factors|
|fct_inorder||Reorder factors levels by first appearance, frequency, or numeric order.|
|fct_unique||Unique values of a factor|
|fct_reorder||Reorder factor levels by sorting along another variable|
|fct_rev||Reverse order of factor levels|
|lvls||Low-level functions for manipulating levels|
|lvls_union||Find all levels in a list of factors|
|fct_c||Concatenate factors, combining levels|
|fct_lump||Lump together least/most common factor levels into "other"|
|fct_match||Test for presence of levels in a factor|
|forcats-package||forcats: Tools for Working with Categorical Variables (Factors)|
|gss_cat||A sample of categorical variables from the General Social survey|
|fct_collapse||Collapse factor levels into manually defined groups|
|fct_relabel||Automatically relabel factor levels, collapse as necessary|
|fct_relevel||Reorder factor levels by hand|
Vignettes of forcats
Last month downloads
|Packaged||2019-02-17 14:15:34 UTC; hadley|
|Date/Publication||2019-02-17 14:40:02 UTC|
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