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The post How to Filter Rows In R? appeared first on Data Science Tutorials

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~```

The post How to Filter Rows In R? appeared first on Data Science Tutorials