Operations with Matrices
Matrices in R support arithmetic operations, both with single numbers and with built-in functions that summarize their values.
Scalar Operations
Applying an arithmetic operation with a single number affects every element in the matrix.
Example
1234m <- matrix(1:9, nrow = 3, byrow = TRUE) # Multiply every element by 3 m * 3
Aggregate Functions
Functions like sum() and mean() compute totals or averages across the entire matrix.
Example
123456m <- matrix(1:9, nrow = 3, byrow = TRUE) # Overall mean of all elements mean(m) # Overall sum of all elements sum(m)
Row and Column Functions
You can also apply these functions to rows or columns separately with rowSums(), rowMeans(), colSums(), and colMeans().
Example
123456m <- matrix(1:9, nrow = 3, byrow = TRUE) # Column sums colSums(m) # Row means rowMeans(m)
These functions make it easy to analyze matrix data by dimension.
Swipe to start coding
You have a matrix named m:
2 4 6 8
10 12 14 16
Your tasks are:
- Divide each element by
2, then add1. Reassign the result to themvariable. - Output the matrix
m. - Output the column totals of the
mmatrix. - Output the mean value of all
melements.
Solution
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Swipe to show menu
Matrices in R support arithmetic operations, both with single numbers and with built-in functions that summarize their values.
Scalar Operations
Applying an arithmetic operation with a single number affects every element in the matrix.
Example
1234m <- matrix(1:9, nrow = 3, byrow = TRUE) # Multiply every element by 3 m * 3
Aggregate Functions
Functions like sum() and mean() compute totals or averages across the entire matrix.
Example
123456m <- matrix(1:9, nrow = 3, byrow = TRUE) # Overall mean of all elements mean(m) # Overall sum of all elements sum(m)
Row and Column Functions
You can also apply these functions to rows or columns separately with rowSums(), rowMeans(), colSums(), and colMeans().
Example
123456m <- matrix(1:9, nrow = 3, byrow = TRUE) # Column sums colSums(m) # Row means rowMeans(m)
These functions make it easy to analyze matrix data by dimension.
Swipe to start coding
You have a matrix named m:
2 4 6 8
10 12 14 16
Your tasks are:
- Divide each element by
2, then add1. Reassign the result to themvariable. - Output the matrix
m. - Output the column totals of the
mmatrix. - Output the mean value of all
melements.
Solution
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