R : Apply Function on Rows

This tutorial explains how to apply functions on rows.

Sample Data
data = read.table(text="
X Y Z
6 5 0
6 3 NA
6 1 5
8 5 3
1 NA 1
8 7 2
2 0 2", header=TRUE)

Apply Function

When we want to apply a function to the rows or columns of a matrix or data frame. It cannot be applied on lists or vectors.

apply arguments

Calculate maximum value across row
apply(data, 1, max)
It returns NA if NAs exist in a row. To ignore NAs, you can use the following line of code.
apply(data, 1, max, na.rm = TRUE)
Calculate mean value across row
apply(data, 1, mean)
apply(data, 1, mean, na.rm = TRUE)
Calculate number of 0s in each row
apply(data == 0, 1, sum, na.rm= TRUE)
Calculate number of values greater than 5 in each row
apply(data > 5, 1,  sum, na.rm= TRUE)
Select all rows having mean value greater than or equal to 4
df = data[apply(data, 1, mean, na.rm = TRUE)>=4,]
Remove rows having NAs
helper = apply(data, 1, function(x){any(is.na(x))})
df2 = data[!helper,]
It can be easily done with df2 = na.omit(data).

Count unique values across row
df3 = apply(data,1, function(x) length(unique(na.omit(x))))
Related Posts
About Author:

Deepanshu founded ListenData with a simple objective - Make analytics easy to understand and follow. He has over 10 years of experience in data science. During his tenure, he has worked with global clients in various domains like Banking, Insurance, Private Equity, Telecom and Human Resource.

1 Response to "R : Apply Function on Rows"
  1. Thanks ! can you do a tutorial about the apply family :) ?

    ReplyDelete

Next → ← Prev
Love this Post? Spread the Word!
Share