During data analysis, you will often be asked to calculate the mean of one or more variables in a data frame. The R programming language provides the
colMeans() function that can help you with this requirement. Please read this article to learn about
colMeans in R and how to use it. Let’s go.
What is the colMeans in R?
colMeans() function in R calculates the average value of columns in a data frame or matrix.
colMeans() function returns a numeric vector containing the average value of each column.
- dataframe[c(…)]: several columns in a dataframe or numeric vector.
- na.rm: discard NA values. The default is FALSE.
How to use the colMeans() function in R?
Here we will give some examples to show how to use the
colMeans() function in practice.
Mean of all columns
Suppose we set the first parameter to the name of the matrix or data frame without selecting specific columns for that data frame. The
colMeans() function will return the means of all columns in the input object.
In the following example, we have a numeric matrix with 4 rows and 4 columns consisting of 16 integers from 1 to 16.
We will use the
colMeans() function to calculate the mean of all the columns of this matrix.
# Create a numeric matrix num_matrix <- matrix(1:16, nrow = 4) # Calculate the means of all columns cat("Means of all columns\n") means <- colMeans(num_matrix) means
Means of all columns  2.5 6.5 10.5 14.5
Mean of specific columns
If we use the
colMeans() function in a data frame with some non-numeric values, there will be an error. We must ensure that only columns with numeric values are selected to avoid errors.
We have a data frame that includes several students’ names and test scores.
In the following example, we will use the
colMeans() function to calculate the mean score of each subject for all students in the list.
# Create a data frame scores <- data.frame( Name = c( "Ali", "Beatriz", "Charles", "Diya", "Eric", "Fatima", "Gabriel", "Hanna" ), Math = c(54, 72, 68, 44, 26, 92, 88, 56), Biology = c(42, 70, NA, 34, 60, 84, 94, 42), English = c(44, 74, 82, 56, 62, 84, 68, 76), Physics = c(24, 36, 44, 38, 52, 28, 98, 46) ) # Calculate the means score of each subject for all students mean <- colMeans(scores[c("Math", "Biology", "English", "Physics")], na.rm = TRUE) # Returns the same result # mean <- colMeans(scores[c(2,3,4,5)], na.rm = TRUE) mean
Math Biology English Physics 62.50000 60.85714 68.25000 45.75000
na.rm parameter is set to
TRUE to ignore NA values.
So we have shared with you how to use
colMeans in R. You must make sure the input columns must be numeric, or else an error will occur. If the input contains NA values, set the
na.rm parameter to
TRUE. Thanks for reading.
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Hello, my name’s Bruce Warren. You can call me Bruce. I’m interested in programming languages, so I am here to share my knowledge of programming languages with you, especially knowledge of C, C++, Java, JS, PHP.
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