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

matrix() Function

Sometimes you may have only one vector that you need to convert into a matrix. How can it be done? The answer is simple - by using the matrix() function.

This function has the following parameters:

These are not all the parameters, but the most important for us.

data - is the vector that we want to use to build the matrix;
nrow - number of rows in a new matrix;
ncol - number of columns in a new matrix;
byrow - logical, should the matrix be filled by rows. It's important to note that the length of the vector filled as the data parameter must be divisible by nrow or ncol. If both parameters are set, then nrow*ncol must equal the vector length.

For example, let's construct a 3x3 matrix with integers from 1 to 9.

As you can see, this matrix was built from above to below first. Let's set parameter byrow to T and compare the results.

As you can see, we filled this matrix from left to right. We were free to leave only one of the nrow or ncol parameters since 9 (number of elements in the vector) is divisible by 3 and returns an integer result.

Task

Given a vector of numbers named num.

Based on this vector, you need to build the following matrix.

Use only the matrix() function, and think about the correct values of parameters.

Task

Given a vector of numbers named num.

Based on this vector, you need to build the following matrix.

Use only the matrix() function, and think about the correct values of parameters.

How does seq() function work? seq(a, b) generates integers from a to b inclusive. seq(a, b, c) generates integers from a to b with the step c.

Everything was clear?

Section 1. Chapter 2

matrix() Function

Sometimes you may have only one vector that you need to convert into a matrix. How can it be done? The answer is simple - by using the matrix() function.

This function has the following parameters:

These are not all the parameters, but the most important for us.

data - is the vector that we want to use to build the matrix;
nrow - number of rows in a new matrix;
ncol - number of columns in a new matrix;
byrow - logical, should the matrix be filled by rows. It's important to note that the length of the vector filled as the data parameter must be divisible by nrow or ncol. If both parameters are set, then nrow*ncol must equal the vector length.

For example, let's construct a 3x3 matrix with integers from 1 to 9.

As you can see, this matrix was built from above to below first. Let's set parameter byrow to T and compare the results.

Task

Given a vector of numbers named num.

Based on this vector, you need to build the following matrix.

Use only the matrix() function, and think about the correct values of parameters.

Task

Given a vector of numbers named num.

Based on this vector, you need to build the following matrix.

Use only the matrix() function, and think about the correct values of parameters.

How does seq() function work? seq(a, b) generates integers from a to b inclusive. seq(a, b, c) generates integers from a to b with the step c.

Everything was clear?

Section 1. Chapter 2

matrix() Function

Sometimes you may have only one vector that you need to convert into a matrix. How can it be done? The answer is simple - by using the matrix() function.

This function has the following parameters:

These are not all the parameters, but the most important for us.

data - is the vector that we want to use to build the matrix;
nrow - number of rows in a new matrix;
ncol - number of columns in a new matrix;
byrow - logical, should the matrix be filled by rows. It's important to note that the length of the vector filled as the data parameter must be divisible by nrow or ncol. If both parameters are set, then nrow*ncol must equal the vector length.

For example, let's construct a 3x3 matrix with integers from 1 to 9.

As you can see, this matrix was built from above to below first. Let's set parameter byrow to T and compare the results.

Task

Given a vector of numbers named num.

Based on this vector, you need to build the following matrix.

Use only the matrix() function, and think about the correct values of parameters.

Task

Given a vector of numbers named num.

Based on this vector, you need to build the following matrix.

Use only the matrix() function, and think about the correct values of parameters.

How does seq() function work? seq(a, b) generates integers from a to b inclusive. seq(a, b, c) generates integers from a to b with the step c.

Everything was clear?

Sometimes you may have only one vector that you need to convert into a matrix. How can it be done? The answer is simple - by using the matrix() function.

This function has the following parameters:

These are not all the parameters, but the most important for us.

data - is the vector that we want to use to build the matrix;
nrow - number of rows in a new matrix;
ncol - number of columns in a new matrix;
byrow - logical, should the matrix be filled by rows. It's important to note that the length of the vector filled as the data parameter must be divisible by nrow or ncol. If both parameters are set, then nrow*ncol must equal the vector length.

For example, let's construct a 3x3 matrix with integers from 1 to 9.

As you can see, this matrix was built from above to below first. Let's set parameter byrow to T and compare the results.

Task

Given a vector of numbers named num.

Based on this vector, you need to build the following matrix.

Use only the matrix() function, and think about the correct values of parameters.

How does seq() function work? seq(a, b) generates integers from a to b inclusive. seq(a, b, c) generates integers from a to b with the step c.

Section 1. Chapter 2

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