How to Apply the Same Function to Every Specified Data Table Variable in R (Example Code)
In this R tutorial you’ll learn how to use the same function for a predefined set of variables.
Setting up the Example
install.packages("data.table") # Install & load data.table package library("data.table") |
install.packages("data.table") # Install & load data.table package library("data.table")
my_tab <- data.table(w = 1:5, # Creating data.table x = c(3, 7, 5, 7, 8), y = LETTERS[1:5], z = 1) my_tab # Return data.table to console # w x y z # 1: 1 3 A 1 # 2: 2 7 B 1 # 3: 3 5 C 1 # 4: 4 7 D 1 # 5: 5 8 E 1 |
my_tab <- data.table(w = 1:5, # Creating data.table x = c(3, 7, 5, 7, 8), y = LETTERS[1:5], z = 1) my_tab # Return data.table to console # w x y z # 1: 1 3 A 1 # 2: 2 7 B 1 # 3: 3 5 C 1 # 4: 4 7 D 1 # 5: 5 8 E 1
Example: Applying the Same Function to Certain Variables of data.table
mod_cols <- c("w", "x", "z") # Variables to be modified |
mod_cols <- c("w", "x", "z") # Variables to be modified
my_tab[ , (mod_cols) := lapply(.SD, "+", 10), .SDcols = mod_cols] # Modify data |
my_tab[ , (mod_cols) := lapply(.SD, "+", 10), .SDcols = mod_cols] # Modify data
my_tab # Return new data.table # w x y z # 1: 11 13 A 11 # 2: 12 17 B 11 # 3: 13 15 C 11 # 4: 14 17 D 11 # 5: 15 18 E 11 |
my_tab # Return new data.table # w x y z # 1: 11 13 A 11 # 2: 12 17 B 11 # 3: 13 15 C 11 # 4: 14 17 D 11 # 5: 15 18 E 11