R: How To Add Column To Data Frame Based On Other Columns

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You can use the following basic syntax to add a column to a data frame in R based on the values in other columns:

#add new column 'col3' with values based on columns 1 and 2 df$col3 <- with(df, ifelse(col1 > col2, value_if_true, value_if_false))

The following examples show how to use this syntax in practice.

Example 1: Add Character Column Based on Other Columns

The following code shows how to add a new character column based on the values in other columns of the data frame:

#create data frame df <- data.frame(team=c('Mavs', 'Cavs', 'Spurs', 'Nets'), scored=c(99, 90, 84, 96), allowed=c(95, 80, 87, 95)) #view data frame df team scored allowed 1 Mavs 99 95 2 Cavs 90 80 3 Spurs 84 87 4 Nets 96 95 #add 'result' column based on values in 'scored' and 'allowed' columns df$result <- with(df, ifelse(scored > allowed, 'Win', 'Loss')) #view updated data frame df team scored allowed result 1 Mavs 99 95 Win 2 Cavs 90 80 Win 3 Spurs 84 87 Loss 4 Nets 96 95 Win

And the following code shows how to add a new character column that combines two ifelse() functions to produce three potential values in a new column:

#create data frame df <- data.frame(team=c('Mavs', 'Cavs', 'Spurs', 'Nets'), scored=c(99, 90, 84, 96), allowed=c(95, 80, 87, 95)) #view data frame df team scored allowed 1 Mavs 99 95 2 Cavs 90 80 3 Spurs 84 87 4 Nets 96 95 #add 'quality' column based on values in 'scored' and 'allowed' columns df$quality <- with(df, ifelse(scored > 95, 'great', ifelse(scored > 85, 'good', 'bad'))) #view updated data frame df team scored allowed quality 1 Mavs 99 95 great 2 Cavs 90 80 good 3 Spurs 84 87 bad 4 Nets 96 95 great

Example 2: Add Numeric Column Based on Other Columns

The following code shows how to add a new numeric column to a data frame based on the values in other columns:

#create data frame df <- data.frame(team=c('Mavs', 'Cavs', 'Spurs', 'Nets'), scored=c(99, 90, 84, 96), allowed=c(95, 80, 87, 95)) #view data frame df team scored allowed 1 Mavs 99 95 2 Cavs 90 80 3 Spurs 84 87 4 Nets 96 95 #add 'lower_score' column based on values in 'scored' and 'allowed' columns df$lower_score <- with(df, ifelse(scored > allowed, allowed, scored)) #view updated data frame df team scored allowed lower_score 1 Mavs 99 95 95 2 Cavs 90 80 80 3 Spurs 84 87 84 4 Nets 96 95 95

Additional Resources

How to Add Columns to Data Frame in R How to Add an Empty Column to a Data Frame in R How to Add an Index Column to Data Frame in R

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