Table of Contents
The median value of rows in R is calculated by first ordering the data in the row from smallest to largest and then finding the middle value in the ordered list. If there is an even number of values, the median is calculated by taking the mean of the two middle values. This gives a better representation of the central tendency of the data than the mean, as it is less affected by outliers.
You can use the following methods to calculate the median value of rows in R:
Method 1: Calculate Median of Rows Using Base R
df$row_median = apply(df, 1, median, na.rm=TRUE)
Method 2: Calculate Median of Rows Using dplyr
library(dplyr) df %>% rowwise() %>% mutate(row_median = median(c_across(where(is.numeric)), na.rm=TRUE))
The following examples show how to use each method in practice.
Example 1: Calculate Median of Rows Using Base R
Suppose we have the following data frame in R that shows the points scored by various basketball players during three different games:
#create data frame
df <- data.frame(game1=c(10, 12, 14, 15, 16, 18, 19),
game2=c(14, 19, 13, 8, 15, 15, 17),
game3=c(9, NA, 15, 25, 26, 30, 19))
#view data frame
df
game1 game2 game3
1 10 14 9
2 12 19 NA
3 14 13 15
4 15 8 25
5 16 15 26
6 18 15 30
7 19 17 19
We can use the apply() function from base R to create a new column that shows the median value of each row:
#calculate median of each row
df$row_median = apply(df, 1, median, na.rm=TRUE)
#view updated data frame
df
game1 game2 game3 row_median
1 10 14 9 10.0
2 12 19 NA 15.5
3 14 13 15 14.0
4 15 8 25 15.0
5 16 15 26 16.0
6 18 15 30 18.0
7 19 17 19 19.0
The new column called row_median contains the median value of each row in the data frame.
Example 2: Calculate Median of Rows Using dplyr
Suppose we have the following data frame in R that shows the points scored by various basketball players during three different games:
#create data frame
df <- data.frame(player=c('A', 'B', 'C', 'D', 'E', 'F', 'G'),
game1=c(10, 12, 14, 15, 16, 18, 19),
game2=c(14, 19, 13, 8, 15, 15, 17),
game3=c(9, NA, 15, 25, 26, 30, 19))
#view data frame
df
player game1 game2 game3
1 A 10 14 9
2 B 12 19 NA
3 C 14 13 15
4 D 15 8 25
5 E 16 15 26
6 F 18 15 30
7 G 19 17 19
We can use the mutate() function from the dplyr package to create a new column that shows the median value of each row for the numeric columns only:
library(dplyr)
#calculate median of rows for numeric columns only
df %>%
rowwise() %>%
mutate(row_median = median(c_across(where(is.numeric)), na.rm=TRUE))
# A tibble: 7 x 5
# Rowwise:
player game1 game2 game3 row_median
1 A 10 14 9 10
2 B 12 19 NA 15.5
3 C 14 13 15 14
4 D 15 8 25 15
5 E 16 15 26 16
6 F 18 15 30 18
7 G 19 17 19 19 The following tutorials explain how to perform other common tasks in R: