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Operation with Matrices

Good! Now we know how to create and customize matrices. It's time to consider the operations we can perform with matrices.

You can perform basic math operations with matrices. Performing a basic operation between a matrix and a single number will perform the respective operation for all matrix elements. For example, for the given matrix below...


python

...we can multiply each element by 3.


              1234567
            
# Vector of integers
num <- 1:9
# Matrix
m <- matrix(num, nrow = 3, ncol = 3, byrow = T)

# Multiply each matrix element by 3
m * 3

As you can see, each matrix element was multiplied by 3. You can also use mean() and sum() functions for matrices. These functions will return the overall mean or total value, respectively. For example,


              1234
            
num <- 1:9
m <- matrix(num, nrow = 3, ncol = 3, byrow = T)
# Calculate overall mean
mean(m)

Additionally, you can also apply these functions to rows or columns separately. These functions are rowSums(), rowMeans(), colSums(), colMeans(). I think it's obvious what each function does according to their names. For example, let's calculate the column sums.


              1234
            
num <- 1:9
m <- matrix(num, nrow = 3, ncol = 3, byrow = T)
# Columns sums
colSums(m)

Let's practice a bit.

Compito

Swipe to start coding

Given matrix named m.


python

Your tasks are:

Divide each element by 2, then add 1. Reassign the result to the m variable.
Output the matrix m.
Output the columns totals of the m matrix.
Output mean value of all m elements.

Soluzione

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Sezione 1. Capitolo 6

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Operation with Matrices

Good! Now we know how to create and customize matrices. It's time to consider the operations we can perform with matrices.


python

...we can multiply each element by 3.


              1234567
            
# Vector of integers
num <- 1:9
# Matrix
m <- matrix(num, nrow = 3, ncol = 3, byrow = T)

# Multiply each matrix element by 3
m * 3


              1234
            
num <- 1:9
m <- matrix(num, nrow = 3, ncol = 3, byrow = T)
# Calculate overall mean
mean(m)


              1234
            
num <- 1:9
m <- matrix(num, nrow = 3, ncol = 3, byrow = T)
# Columns sums
colSums(m)

Let's practice a bit.

Compito

Swipe to start coding

Given matrix named m.


python

Your tasks are:

Divide each element by 2, then add 1. Reassign the result to the m variable.
Output the matrix m.
Output the columns totals of the m matrix.
Output mean value of all m elements.

Soluzione

Cambia al desktop per esercitarti nel mondo realeContinua da dove ti trovi utilizzando una delle opzioni seguenti

Tutto è chiaro?

Grazie per i tuoi commenti!

Sezione 1. Capitolo 6

Cambia al desktop per esercitarti nel mondo realeContinua da dove ti trovi utilizzando una delle opzioni seguenti