How to Compute the Standard Deviation Across Rows in R (Example Code)
In this R programming article you’ll learn how to get the standard deviation across rows of a data matrix.
Creating Example Data
data(iris) # Load and modify example data my_iris <- iris[ , 1:4] head(my_iris) # Head of example data # Sepal.Length Sepal.Width Petal.Length Petal.Width # 1 5.1 3.5 1.4 0.2 # 2 4.9 3.0 1.4 0.2 # 3 4.7 3.2 1.3 0.2 # 4 4.6 3.1 1.5 0.2 # 5 5.0 3.6 1.4 0.2 # 6 5.4 3.9 1.7 0.4 |
data(iris) # Load and modify example data my_iris <- iris[ , 1:4] head(my_iris) # Head of example data # Sepal.Length Sepal.Width Petal.Length Petal.Width # 1 5.1 3.5 1.4 0.2 # 2 4.9 3.0 1.4 0.2 # 3 4.7 3.2 1.3 0.2 # 4 4.6 3.1 1.5 0.2 # 5 5.0 3.6 1.4 0.2 # 6 5.4 3.9 1.7 0.4
Example: Compute Standard Deviation Across Rows Using apply() Function
my_iris_sd <- cbind(my_iris, # Standard deviations across rows sd_by_row = apply(my_iris, 1, sd)) head(my_iris_sd) # Display head of data with sd # Sepal.Length Sepal.Width Petal.Length Petal.Width sd_by_row # 1 5.1 3.5 1.4 0.2 2.179449 # 2 4.9 3.0 1.4 0.2 2.036950 # 3 4.7 3.2 1.3 0.2 1.997498 # 4 4.6 3.1 1.5 0.2 1.912241 # 5 5.0 3.6 1.4 0.2 2.156386 # 6 5.4 3.9 1.7 0.4 2.230844 |
my_iris_sd <- cbind(my_iris, # Standard deviations across rows sd_by_row = apply(my_iris, 1, sd)) head(my_iris_sd) # Display head of data with sd # Sepal.Length Sepal.Width Petal.Length Petal.Width sd_by_row # 1 5.1 3.5 1.4 0.2 2.179449 # 2 4.9 3.0 1.4 0.2 2.036950 # 3 4.7 3.2 1.3 0.2 1.997498 # 4 4.6 3.1 1.5 0.2 1.912241 # 5 5.0 3.6 1.4 0.2 2.156386 # 6 5.4 3.9 1.7 0.4 2.230844