How To Apply a Function to Each Column in R

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DataDaft

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Published on June 30, 2019 4:39:21 PM ● Video Link: https://www.youtube.com/watch?v=FUOpsBTy_as

Category:

Guide

Duration: 2:06

6,121 views

46

The apply() function in lets you apply a given function to each column, which is useful for summarizes and aggregations.

Code used in this clip:

# Load a data set

data = mtcars
head(mtcars)

# Apply a built in function to columns

apply(X = data, # Data to apply function to
FUN = max, # Function to apply
MARGIN = 2) # Margin (axis) to apply over.
# 1 = rows, 2 = columns

# Apply a custom function to columns
my_function = function(x){
return(max(x) - min(x))
}

apply(X = data, # Data to apply function to
FUN = my_function, # Function to apply
MARGIN = 2) # Margin (axis) to apply over.



Code Clips are basic code explanations in 2 minutes or less. They are intended to be short reference guides that provide quick breakdowns and copy/paste access to code needed to accomplish common data science tasks. Think Stack Overflow with a video explanation.


* Note: YouTube does not allow greater than or less than symbols in the text description, so the code above will not be exactly the same as the code shown in the video! For R that means I may use = for assignment and the special Unicode large ＜ and ＞ symbols in place of the standard sized ones for dplyr pipes and comparisons. These special symbols should work as expected for R code on Windows, but may need to be replaced with standard greater than and less than symbols for other operating systems.