How to Filter Rows In R?
How to Filter Rows In R, it’s common to want to subset a data frame based on particular conditions. Fortunately, using the filter() function from the dplyr package makes this simple.
library(dplyr)
This tutorial uses the built-in dplyr dataset starwars to show numerous examples of how to utilize this function in practice.
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look at the first six rows of the Star Wars dataset
head(starwars)
# A tibble: 6 x 13 name height mass hair_color skin_color eye_color birth_year gender homeworld 1 Luke~ 172 77 blond fair blue 19 male Tatooine 2 C-3PO 167 75 <NA> gold yellow 112 <NA> Tatooine 3 R2-D2 96 32 <NA> white, bl~ red 33 <NA> Naboo 4 Dart~ 202 136 none white yellow 41.9 male Tatooine 5 Leia~ 150 49 brown light brown 19 female Alderaan 6 Owen~ 178 120 brown, gr~ light blue 52 male Tatooine # ... with 4 more variables: species , films , vehicles , # starships
Example 1: Filter Rows Equal to Some Value
The code below explains how to find rows in the dataset when the variable ‘species’ equals Droid.
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starwars %>% filter(species == 'Droid')
# A tibble: 5 x 13 name height mass hair_color skin_color eye_color birth_year gender homeworld 1 C-3PO 167 75 gold yellow 112 Tatooine 2 R2-D2 96 32 white, bl~ red 33 Naboo 3 R5-D4 97 32 white, red red NA Tatooine 4 IG-88 200 140 none metal red 15 none 5 BB8 NA NA none none black NA none
This criterion was met by 5 rows in the dataset, as indicated by #A tibble: 5 x 13.
Example 2: Using ‘And’ to Filter Rows
We may also look for rows with Droid as the species and red as the eye color.
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starwars %>% filter(species == 'Droid' & eye_color == 'red')
# A tibble: 3 x 13 name height mass hair_color skin_color eye_color birth_year gender homeworld 1 R2-D2 96 32 <NA> white, bl~ red 33 <NA> Naboo 2 R5-D4 97 32 <NA> white, red red NA <NA> Tatooine 3 IG-88 200 140 none metal red 15 none <NA>
These criteria were met by three rows in the dataset.
Example 3: Using ‘Or’ to Filter Rows
We may also look for rows with Droid as the species or red as the eye color:
starwars %>% filter(species == 'Droid' | eye_color == 'red')
# A tibble: 7 x 13 name height mass hair_color skin_color eye_color birth_year gender homeworld 1 C-3PO 167 75 <NA> gold yellow 112 <NA> Tatooine 2 R2-D2 96 32 <NA> white, bl~ red 33 <NA> Naboo 3 R5-D4 97 32 <NA> white, red red NA <NA> Tatooine 4 IG-88 200 140 none metal red 15 none <NA> 5 Bossk 190 113 none green red 53 male Trandosha 6 Nute~ 191 90 none mottled g~ red NA male Cato Nei~ 7 BB8 NA NA none none black NA none <NA>
These criteria were met by 7 rows in the dataset, as can be seen.
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Example 4: Filter Rows with Values in a List
We can also look for rows where the eye color is part of a color palette.
starwars %>% filter(eye_color %in% c('blue', 'yellow', 'red'))# A tibble: 35 x 13 name height mass hair_color skin_color eye_color birth_year gender 1 Luke~ 172 77 blond fair blue 19 male 2 C-3PO 167 75 <NA> gold yellow 112 <NA> 3 R2-D2 96 32 <NA> white, bl~ red 33 <NA> 4 Dart~ 202 136 none white yellow 41.9 male 5 Owen~ 178 120 brown, gr~ light blue 52 male 6 Beru~ 165 75 brown light blue 47 female 7 R5-D4 97 32 <NA> white, red red NA <NA> 8 Anak~ 188 84 blond fair blue 41.9 male 9 Wilh~ 180 NA auburn, g~ fair blue 64 male 10 Chew~ 228 112 brown unknown blue 200 male
We can observe that 35 of the rows in the dataset had blue, yellow, or red eyes.
Example 5: Filter Rows Using Less Than or Greater Than
We can also use less than and greater than operations on numeric variables to filter rows.
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find rows with a height of more than 250
starwars %>% filter(height > 250)
# A tibble: 1 x 13 name height mass hair_color skin_color eye_color birth_year gender homeworld 1 Yara~ 264 NA none white yellow NA male Quermia
Look for rows with a height of 200 to 230.
starwars %>% filter(height > 200 & height < 230)
# A tibble: 5 x 13 name height mass hair_color skin_color eye_color birth_year gender homeworld 1 Dart~ 202 136 none white yellow 41.9 male Tatooine 2 Rugo~ 206 NA none green orange NA male Naboo 3 Taun~ 213 NA none grey black NA female Kamino 4 Grie~ 216 159 none brown, wh~ green, y~ NA male Kalee 5 Tion~ 206 80 none grey black NA male Utapau
discover rows with a height that is higher than the average height.
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starwars %>% filter(height > mean(height, na.rm = TRUE))
name height mass hair_color skin_color eye_color birth_year sex gender <chr> <int> <dbl> <chr> <chr> <chr> <dbl> <chr> <chr> 1 Darth V~ 202 136 none white yellow 41.9 male mascu~ 2 Owen La~ 178 120 brown, grey light blue 52 male mascu~ 3 Biggs D~ 183 84 black light brown 24 male mascu~ 4 Obi-Wan~ 182 77 auburn, wh~ fair blue-gray 57 male mascu~ 5 Anakin ~ 188 84 blond fair blue 41.9 male mascu~ 6 Wilhuff~ 180 NA auburn, gr~ fair blue 64 male mascu~ 7 Chewbac~ 228 112 brown unknown blue 200 male mascu~ 8 Han Solo 180 80 brown fair brown 29 male mascu~ 9 Jabba D~ 175 1358 NA green-tan~ orange 600 herma~ mascu~ 10 Jek Ton~ 180 110 brown fair blue NA male mascu~
