The %in% operator in R allows you to determine whether or not an element belongs to a vector or data frame.
This tutorial provides three examples of how to use this function in different scenarios.
Example 1: Use %in% with Vectors
We can use the %in% operator to determine how many elements of one vector belong to another vector:
#define two vectors of data data1 #produce new vector that contains elements of data1 that are in data2 data1[data1 %in% data2] [1] 3 5
We can see that the values 3 and 5 are the only elements from the vector titled data2 that are in the vector titled data1.
Example 2: Use %in% to filter Data Frames
We can also use the %in% operator to filter for rows in a data frame that contain certain values:
#define data frame df #view data frame df team points assists 1 A 67 14 2 A 72 16 3 B 77 12 4 B 89 22 5 B 84 25 6 C 97 20 #produce new data frame that only contains rows where team is 'B' df_new %in% c('B'), ] df_new team points assists 3 B 77 12 4 B 89 22 5 B 84 25 #produce new data frame that only contains rows where team is 'B' or 'C' df_new2 %in% c('B', 'C'), ] df_new2 team points assists 3 B 77 12 4 B 89 22 5 B 84 25 6 C 97 20
Example 3: Use %in% to Create Data Frame Columns
We can also use the %in% operator to create new data frame columns.
For example, the following code shows how to create a new column titled division that places teams ‘A’ and ‘C’ in the ‘East’ and teams ‘B’ in the ‘West’:
library(dplyr) #define data frame df #view data frame df team points assists 1 A 67 14 2 A 72 16 3 B 77 12 4 B 89 22 5 B 84 25 6 C 97 20 #create new column called division df$division = if_else(df$team %in% c('A', 'C'), 'East', 'West') df team points assists division 1 A 67 14 East 2 A 72 16 East 3 B 77 12 West 4 B 89 22 West 5 B 84 25 West 6 C 97 20 East
Additional Resources
How to Combine Two Columns into One in R
How to Append Rows to a Data Frame in R
How to Compare Two Columns in R