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R Introduction: Part II
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R Introduction: Part II

R Introduction: Part II

1. Matrices
What is a Matrix?matrix() FunctionTransposingMatrix IndexationNamingsOperation with MatricesSales and Revenue
2. Data Frames
What is a Data Frame?data.frame() FunctionColumns AccessorsLogical IndexingManipulating ColumnsManipulating RowsData Extraction
3. Lists
What is a List?NamingsExtracting List ElementsModifying

bookOperation 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.


              
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
copy

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)
copy

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)
copy

Let's practice a bit.

Tarefa

Given matrix named m.

Your tasks are:

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

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Tudo estava claro?

Como podemos melhorá-lo?

Obrigado pelo seu feedback!

Seção 1. Capítulo 6
toggle bottom row

bookOperation 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.


              
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
copy

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)
copy

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)
copy

Let's practice a bit.

Tarefa

Given matrix named m.

Your tasks are:

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

Switch to desktopMude para o desktop para praticar no mundo realContinue de onde você está usando uma das opções abaixo
Tudo estava claro?

Como podemos melhorá-lo?

Obrigado pelo seu feedback!

Seção 1. Capítulo 6
toggle bottom row

bookOperation 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.


              
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
copy

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)
copy

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)
copy

Let's practice a bit.

Tarefa

Given matrix named m.

Your tasks are:

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

Switch to desktopMude para o desktop para praticar no mundo realContinue de onde você está usando uma das opções abaixo
Tudo estava claro?

Como podemos melhorá-lo?

Obrigado pelo seu feedback!

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.


              
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
copy

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)
copy

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)
copy

Let's practice a bit.

Tarefa

Given matrix named m.

Your tasks are:

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

Switch to desktopMude para o desktop para praticar no mundo realContinue de onde você está usando uma das opções abaixo
Seção 1. Capítulo 6
Switch to desktopMude para o desktop para praticar no mundo realContinue de onde você está usando uma das opções abaixo
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