Welcome back! Up until now, we've covered some essential techniques for managing your datasets with the dplyr package in R. We've learned how to select specific columns, filter rows based on conditions, and summarize and group data. Now, it's time to take your data manipulation skills to the next level by learning how to mutate (or transform) data and arrange it in a specific order.

In this lesson, you'll explore two critical functionalities:

1. Mutating Data: Adding or transforming columns in your data frame using the mutate function.
2. Arranging Data: Sorting your data in a specific order using the arrange function.

We'll use straightforward examples to make these concepts easy to grasp. Let’s dive into each of these functionalities.

First, we'll set up an example data frame that we'll use throughout this lesson:

R
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1# Example data frame
2data <- data.frame(
3  Name = c("Alice", "Bob", "Charlie", "David"),
4  Score = c(85, 95, 78, 92)
5)
6
7# Print the example data frame
8print(data)
9
10# Output:
11#      Name Score
12# 1   Alice    85
13# 2     Bob    95
14# 3 Charlie    78
15# 4   David    92

This data frame contains the names of four individuals along with their respective scores.

The mutate function allows us to add new columns or transform existing ones. For instance, suppose we want to add a new column, ScorePlus10, which is each person's score incremented by 10.

R
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1# Example data frame
2data <- data.frame(
3  Name = c("Alice", "Bob", "Charlie", "David"),
4  Score = c(85, 95, 78, 92)
5)
6
7# Add a new column
8mutated_data <- mutate(data, ScorePlus10 = Score + 10)
9
10# Print the mutated data
11print(mutated_data)
12
13# Output:
14#      Name Score ScorePlus10
15# 1   Alice    85          95
16# 2     Bob    95         105
17# 3 Charlie    78          88
18# 4   David    92         102

Here, mutate adds a new column called ScorePlus10 to the data frame, where each entry is the original Score plus 10.

The arrange function helps us sort the data in a specific order. For example, to sort the data by Score in descending order, we can do the following:

R
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1# Example data frame
2data <- data.frame(
3  Name = c("Alice", "Bob", "Charlie", "David"),
4  Score = c(85, 95, 78, 92)
5)
6
7# Add a new column
8mutated_data <- mutate(data, ScorePlus10 = Score + 10)
9
10# Arrange data by Score in descending order
11arranged_data <- arrange(mutated_data, desc(Score))
12
13# Print the descending arranged data
14print(arranged_data)
15
16# Output:
17#      Name Score ScorePlus10
18# 1     Bob    95         105
19# 2   David    92         102
20# 3   Alice    85          95
21# 4 Charlie    78          88

In this code snippet, arrange sorts the mutated_data data frame by the Score column in descending order.

To sort the data by Score in ascending order, we can do the following:

R
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1# Example data frame
2data <- data.frame(
3  Name = c("Alice", "Bob", "Charlie", "David"),
4  Score = c(85, 95, 78, 92)
5)
6
7# Add a new column
8mutated_data <- mutate(data, ScorePlus10 = Score + 10)
9
10# Arrange data by Score in ascending order
11arranged_data_asc <- arrange(mutated_data, Score)
12
13# Print the ascending arranged data
14print(arranged_data_asc)
15
16# Output:
17#      Name Score ScorePlus10
18# 1 Charlie    78          88
19# 2   Alice    85          95
20# 3   David    92         102
21# 4     Bob    95         105

Here, arrange sorts the mutated_data data frame by the Score column in ascending order. No need to use any function for ascending order, as it is the default behavior of arrange.

Mutating and arranging data are foundational skills in data wrangling.

• Mutating Data: This technique allows you to create new variables or transform existing ones based on your needs. It's useful for tasks such as feature engineering in machine learning, where you may need to create new features from raw data.

• Arranging Data: Sorting your data helps you see patterns more clearly and make your datasets more readable. For example, arranging sales data from the highest to the lowest can help you immediately spot your top-performing products.

By mastering these functions, you'll be better equipped to prepare your data for analysis and reporting, ensuring you draw more meaningful insights from your datasets.

Excited to start mutating and arranging data? Let's jump into the practice section and get hands-on with these powerful techniques.