R: How to Drop Rows that Contain a Specific String

You can use the following syntax to drop rows that contain a certain string in a data frame in R:

df[!grepl('string', df$column),]

This tutorial provides several examples of how to use this syntax in practice with the following data frame in R:

#create data frame
df frame(team=c('A', 'A', 'A', 'B', 'B', 'C'),
                 conference=c('East', 'East', 'East', 'West', 'West', 'East'),
                 points=c(11, 8, 10, 6, 6, 5))

#view data frame
df

  team conference points
1    A       East     11
2    A       East      8
3    A       East     10
4    B       West      6
5    B       West      6
6    C       East      5

Example 1: Drop Rows that Contain a Specific String

The following code shows how to drop all rows in the data frame that contain ‘A’ in the team column:

df[!grepl('A', df$team),]

  team conference points
4    B       West      6
5    B       West      6
6    C       East      5

Or we could drop all rows in the data frame that contain ‘West’ in the conference column:

df[!grepl('West', df$conference),]

  team conference points
1    A       East     11
2    A       East      8
3    A       East     10
6    C       East      5

Example 2: Drop Rows that Contain a String in a List

The following code shows how to drop all rows in the data frame that contain ‘A’ or ‘B’ in the team column:

df[!grepl('A|B', df$team),]

6    C       East      5

We could also define a vector of strings and then remove all rows in the data frame that contain any of the strings in the vector in the team column:

#define vector of strings
remove A', 'B')

#remove rows that contain any string in the vector in the team column
df[!grepl(paste(remove, collapse='|'), df$team),]

6    C       East      5

Notice that both methods lead to the same result.

Additional Resources

How to Remove Rows with Some or All NAs in R
How to Remove Duplicate Rows in R
How to Sum Specific Rows in R