The filter() function is used to subset a data frame,retaining all rows that satisfy your conditions.To be retained, the row must produce a value of TRUE for all conditions.Note that when a condition evaluates to NAthe row will be dropped, unlike base subsetting with [.
Usage
filter(.data, ..., .by = NULL, .preserve = FALSE)Arguments
- .data
A data frame, data frame extension (e.g. a tibble), or alazy data frame (e.g. from dbplyr or dtplyr). See Methods, below, formore details.
- ...
<
data-masking> Expressions thatreturn a logical value, and are defined in terms of the variables in.data. If multiple expressions are included, they are combined with the&operator. Only rows for which all conditions evaluate toTRUEarekept.- .by
<
tidy-select> Optionally, a selection of columns togroup by for just this operation, functioning as an alternative togroup_by(). Fordetails and examples, see ?dplyr_by.- .preserve
Relevant when the
.datainput is grouped.If.preserve = FALSE(the default), the grouping structureis recalculated based on the resulting data, otherwise the grouping is kept as is.
Value
An object of the same type as .data. The output has the following properties:
Rows are a subset of the input, but appear in the same order.
Columns are not modified.
The number of groups may be reduced (if
.preserveis notTRUE).Data frame attributes are preserved.
Details
The filter() function is used to subset the rows of.data, applying the expressions in ... to the column values to determine whichrows should be retained. It can be applied to both grouped and ungrouped data (see group_by() andungroup()). However, dplyr is not yet smart enough to optimise the filteringoperation on grouped datasets that do not need grouped calculations. For thisreason, filtering is often considerably faster on ungrouped data.
Useful filter functions
There are many functions and operators that are useful when constructing theexpressions used to filter the data:
Grouped tibbles
Because filtering expressions are computed within groups, they mayyield different results on grouped tibbles. This will be the caseas soon as an aggregating, lagging, or ranking function isinvolved. Compare this ungrouped filtering:
starwars %>% filter(mass > mean(mass, na.rm = TRUE))With the grouped equivalent:
starwars %>% group_by(gender) %>% filter(mass > mean(mass, na.rm = TRUE))In the ungrouped version, filter() compares the value of mass in each row tothe global average (taken over the whole data set), keeping only the rows withmass greater than this global average. In contrast, the grouped version calculatesthe average mass separately for each gender group, and keeps rows with mass greaterthan the relevant within-gender average.
Methods
This function is a generic, which means that packages can provideimplementations (methods) for other classes. See the documentation ofindividual methods for extra arguments and differences in behaviour.
The following methods are currently available in loaded packages:dbplyr (tbl_lazy), dplyr (data.frame, ts).
See also
Other single table verbs: arrange(),mutate(),reframe(),rename(),select(),slice(),summarise()
Examples
# Filtering by one criterionfilter(starwars, species == "Human")#> # A tibble: 35 × 14#> name height mass hair_color skin_color eye_color birth_year sex #> <chr> <int> <dbl> <chr> <chr> <chr> <dbl> <chr>#> 1 Luke Sky… 172 77 blond fair blue 19 male #> 2 Darth Va… 202 136 none white yellow 41.9 male #> 3 Leia Org… 150 49 brown light brown 19 fema…#> 4 Owen Lars 178 120 brown, gr… light blue 52 male #> 5 Beru Whi… 165 75 brown light blue 47 fema…#> 6 Biggs Da… 183 84 black light brown 24 male #> 7 Obi-Wan … 182 77 auburn, w… fair blue-gray 57 male #> 8 Anakin S… 188 84 blond fair blue 41.9 male #> 9 Wilhuff … 180 NA auburn, g… fair blue 64 male #> 10 Han Solo 180 80 brown fair brown 29 male #> # ℹ 25 more rows#> # ℹ 6 more variables: gender <chr>, homeworld <chr>, species <chr>,#> # films <list>, vehicles <list>, starships <list>filter(starwars, mass > 1000)#> # A tibble: 1 × 14#> name height mass hair_color skin_color eye_color birth_year sex #> <chr> <int> <dbl> <chr> <chr> <chr> <dbl> <chr>#> 1 Jabba Des… 175 1358 NA green-tan… orange 600 herm…#> # ℹ 6 more variables: gender <chr>, homeworld <chr>, species <chr>,#> # films <list>, vehicles <list>, starships <list># Filtering by multiple criteria within a single logical expressionfilter(starwars, hair_color == "none" & eye_color == "black")#> # A tibble: 9 × 14#> name height mass hair_color skin_color eye_color birth_year sex #> <chr> <int> <dbl> <chr> <chr> <chr> <dbl> <chr>#> 1 Nien Nunb 160 68 none grey black NA male #> 2 Gasgano 122 NA none white, bl… black NA male #> 3 Kit Fisto 196 87 none green black NA male #> 4 Plo Koon 188 80 none orange black 22 male #> 5 Lama Su 229 88 none grey black NA male #> 6 Taun We 213 NA none grey black NA fema…#> 7 Shaak Ti 178 57 none red, blue… black NA fema…#> 8 Tion Medon 206 80 none grey black NA male #> 9 BB8 NA NA none none black NA none #> # ℹ 6 more variables: gender <chr>, homeworld <chr>, species <chr>,#> # films <list>, vehicles <list>, starships <list>filter(starwars, hair_color == "none" | eye_color == "black")#> # A tibble: 39 × 14#> name height mass hair_color skin_color eye_color birth_year sex #> <chr> <int> <dbl> <chr> <chr> <chr> <dbl> <chr>#> 1 Darth Va… 202 136 none white yellow 41.9 male #> 2 Greedo 173 74 NA green black 44 male #> 3 IG-88 200 140 none metal red 15 none #> 4 Bossk 190 113 none green red 53 male #> 5 Lobot 175 79 none light blue 37 male #> 6 Ackbar 180 83 none brown mot… orange 41 male #> 7 Nien Nunb 160 68 none grey black NA male #> 8 Nute Gun… 191 90 none mottled g… red NA male #> 9 Jar Jar … 196 66 none orange orange 52 male #> 10 Roos Tar… 224 82 none grey orange NA male #> # ℹ 29 more rows#> # ℹ 6 more variables: gender <chr>, homeworld <chr>, species <chr>,#> # films <list>, vehicles <list>, starships <list># When multiple expressions are used, they are combined using &filter(starwars, hair_color == "none", eye_color == "black")#> # A tibble: 9 × 14#> name height mass hair_color skin_color eye_color birth_year sex #> <chr> <int> <dbl> <chr> <chr> <chr> <dbl> <chr>#> 1 Nien Nunb 160 68 none grey black NA male #> 2 Gasgano 122 NA none white, bl… black NA male #> 3 Kit Fisto 196 87 none green black NA male #> 4 Plo Koon 188 80 none orange black 22 male #> 5 Lama Su 229 88 none grey black NA male #> 6 Taun We 213 NA none grey black NA fema…#> 7 Shaak Ti 178 57 none red, blue… black NA fema…#> 8 Tion Medon 206 80 none grey black NA male #> 9 BB8 NA NA none none black NA none #> # ℹ 6 more variables: gender <chr>, homeworld <chr>, species <chr>,#> # films <list>, vehicles <list>, starships <list># The filtering operation may yield different results on grouped# tibbles because the expressions are computed within groups.## The following filters rows where `mass` is greater than the# global average:starwars %>% filter(mass > mean(mass, na.rm = TRUE))#> # A tibble: 10 × 14#> name height mass hair_color skin_color eye_color birth_year sex #> <chr> <int> <dbl> <chr> <chr> <chr> <dbl> <chr>#> 1 Darth Va… 202 136 none white yellow 41.9 male #> 2 Owen Lars 178 120 brown, gr… light blue 52 male #> 3 Chewbacca 228 112 brown unknown blue 200 male #> 4 Jabba De… 175 1358 NA green-tan… orange 600 herm…#> 5 Jek Tono… 180 110 brown fair blue NA NA #> 6 IG-88 200 140 none metal red 15 none #> 7 Bossk 190 113 none green red 53 male #> 8 Dexter J… 198 102 none brown yellow NA male #> 9 Grievous 216 159 none brown, wh… green, y… NA male #> 10 Tarfful 234 136 brown brown blue NA male #> # ℹ 6 more variables: gender <chr>, homeworld <chr>, species <chr>,#> # films <list>, vehicles <list>, starships <list># Whereas this keeps rows with `mass` greater than the gender# average:starwars %>% group_by(gender) %>% filter(mass > mean(mass, na.rm = TRUE))#> # A tibble: 15 × 14#> # Groups: gender [3]#> name height mass hair_color skin_color eye_color birth_year sex #> <chr> <int> <dbl> <chr> <chr> <chr> <dbl> <chr>#> 1 Darth V… 202 136 none white yellow 41.9 male #> 2 Owen La… 178 120 brown, gr… light blue 52 male #> 3 Beru Wh… 165 75 brown light blue 47 fema…#> 4 Chewbac… 228 112 brown unknown blue 200 male #> 5 Jabba D… 175 1358 NA green-tan… orange 600 herm…#> 6 Jek Ton… 180 110 brown fair blue NA NA #> 7 IG-88 200 140 none metal red 15 none #> 8 Bossk 190 113 none green red 53 male #> 9 Ayla Se… 178 55 none blue hazel 48 fema…#> 10 Gregar … 185 85 black dark brown NA NA #> 11 Luminar… 170 56.2 black yellow blue 58 fema…#> 12 Zam Wes… 168 55 blonde fair, gre… yellow NA fema…#> 13 Shaak Ti 178 57 none red, blue… black NA fema…#> 14 Grievous 216 159 none brown, wh… green, y… NA male #> 15 Tarfful 234 136 brown brown blue NA male #> # ℹ 6 more variables: gender <chr>, homeworld <chr>, species <chr>,#> # films <list>, vehicles <list>, starships <list># To refer to column names that are stored as strings, use the `.data` pronoun:vars <- c("mass", "height")cond <- c(80, 150)starwars %>% filter( .data[[vars[[1]]]] > cond[[1]], .data[[vars[[2]]]] > cond[[2]] )#> # A tibble: 21 × 14#> name height mass hair_color skin_color eye_color birth_year sex #> <chr> <int> <dbl> <chr> <chr> <chr> <dbl> <chr>#> 1 Darth Va… 202 136 none white yellow 41.9 male #> 2 Owen Lars 178 120 brown, gr… light blue 52 male #> 3 Biggs Da… 183 84 black light brown 24 male #> 4 Anakin S… 188 84 blond fair blue 41.9 male #> 5 Chewbacca 228 112 brown unknown blue 200 male #> 6 Jabba De… 175 1358 NA green-tan… orange 600 herm…#> 7 Jek Tono… 180 110 brown fair blue NA NA #> 8 IG-88 200 140 none metal red 15 none #> 9 Bossk 190 113 none green red 53 male #> 10 Ackbar 180 83 none brown mot… orange 41 male #> # ℹ 11 more rows#> # ℹ 6 more variables: gender <chr>, homeworld <chr>, species <chr>,#> # films <list>, vehicles <list>, starships <list># Learn more in ?rlang::args_data_masking