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The process of dropping rows from a dataset that contain a specific string using R involves utilizing the “grep” function to search for the specific string within the dataset and then using the “subset” function to remove the rows that contain the string. This can be done by specifying the condition for which rows to be removed within the “subset” function. This method allows for efficient and precise removal of rows containing the specific string from the dataset.
R: 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$column),]
This tutorial provides several examples of how to use this syntax in practice with the following data frame in R:
#create data frame df <- data.frame(team=c('A', 'A', 'A', 'B', 'B', 'C'), conference=c('East', 'East', 'East', 'West', 'West', 'East'), points=c(11, 8, 10, 6, 6, 5)) #view data frame df team conference points 1 A East 11 2 A East 8 3 A East 10 4 B West 6 5 B West 6 6 C East 5
Example 1: Drop Rows that Contain a Specific String
The following code shows how to drop all rows in the data frame that contain ‘A’ in the team column:
df[!grepl('A', df$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 <- c('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.