Course Content

R Introduction: Part II

1. Matrices

What is a Matrix?matrix() Function Transposing Matrix Indexation Namings Operation with Matrices Sales and Revenue

2. Data Frames

What is a Data Frame?data.frame() Function Columns Accessors Logical Indexing Manipulating Columns Manipulating Rows Data Extraction

3. Lists

What is a List?Namings Extracting List Elements Modifying

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...

...we can multiply each element by 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,

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.

Let's practice a bit.

Task

Given matrix named m.

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.

Task

Given matrix named m.

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.

Everything was clear?

Section 1. Chapter 6

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.

...we can multiply each element by 3.

Let's practice a bit.

Task

Given matrix named m.

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.

Task

Given matrix named m.

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.

Everything was clear?

Section 1. Chapter 6

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.

...we can multiply each element by 3.

Let's practice a bit.

Task

Given matrix named m.

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.

Task

Given matrix named m.

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.

Everything was clear?

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

...we can multiply each element by 3.

Let's practice a bit.

Task

Given matrix named m.

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.

Section 1. Chapter 6

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