Ordered factors in R Programming - Interactive Code Practice

Practice - 5 Tasks

1fill in blank

easy

Complete the code to create an ordered factor from the vector 'sizes'.

R Programming

sizes <- c("small", "medium", "large")
ordered_sizes <- factor(sizes, levels = c("small", "medium", "large"), ordered = [1])

Drag options to blanks, or click blank then click option'

A"TRUE"

BFALSE

C1

DTRUE

Attempts:

3 left

💡 Hint

Common Mistakes

Using FALSE instead of TRUE for the 'ordered' argument.

Passing 'TRUE' as a string instead of a logical value.

Setting ordered = TRUE creates an ordered factor.

2fill in blank

medium

Complete the code to check if 'ordered_sizes' is an ordered factor.

R Programming

is.ordered([1])

Drag options to blanks, or click blank then click option'

Afactor

Bsizes

Cordered_sizes

Dlevels

Attempts:

3 left

💡 Hint

Common Mistakes

Passing the original vector instead of the factor.

Passing the function name 'factor' instead of a variable.

The function is.ordered() checks if the object is an ordered factor. Here, we check ordered_sizes.

3fill in blank

hard

Fix the error in the code to create an ordered factor with levels 'low', 'medium', 'high'.

R Programming

levels <- c("low", "medium", "high")
values <- c("medium", "high", "low")
factor_values <- factor(values, levels = levels, ordered = [1])

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ATRUE

B1

C"TRUE"

DFALSE

Attempts:

3 left

💡 Hint

Common Mistakes

Using FALSE or a string instead of TRUE.

Passing numeric 1 instead of logical TRUE.

To create an ordered factor, ordered must be set to TRUE (logical).

4fill in blank

hard

Fill both blanks to create an ordered factor with levels 'beginner', 'intermediate', 'advanced' and check if it is ordered.

R Programming

levels <- c("beginner", "intermediate", "advanced")
skills <- c("advanced", "beginner", "intermediate")
skill_factor <- factor(skills, levels = levels, ordered = [1])
check <- is.ordered([2])

Drag options to blanks, or click blank then click option'

ATRUE

BFALSE

Cskills

Dskill_factor

Attempts:

3 left

💡 Hint

Common Mistakes

Using FALSE for the ordered argument.

Checking the original vector instead of the factor.

Set ordered = TRUE to create an ordered factor, then check if skill_factor is ordered.

5fill in blank

hard

Fill all three blanks to create an ordered factor from 'grades', set levels, and check if it is ordered.

R Programming

grades <- c("B", "A", "C")
levels <- c("C", [1], "A")
ordered_grades <- factor(grades, levels = levels, ordered = [2])
result <- is.ordered([3])

Drag options to blanks, or click blank then click option'

A"B"

BTRUE

Cordered_grades

DFALSE

Attempts:

3 left

💡 Hint

Common Mistakes

Leaving out the middle level in levels.

Using FALSE for ordered argument.

Checking the original vector instead of the factor.

Insert "B" as the middle level, set ordered = TRUE, and check if ordered_grades is ordered.

Practice

1. What is the main purpose of creating an ordered factor in R?

easy

A. To store numeric data more efficiently

B. To keep categories in a specific order and allow comparisons like greater than or less than

C. To convert character strings into numeric values automatically

D. To remove duplicate values from a vector

Solution

1. Step 1: Understand what ordered factors do

   Ordered factors keep categories in a specific order defined by the user.

2. Step 2: Recognize the comparison feature

   They allow comparisons like greater than or less than between categories.

3. Final Answer:

   To keep categories in a specific order and allow comparisons like greater than or less than -> Option B

4. Quick Check:

   Ordered factors = ordered categories with comparison [OK]

Hint: Ordered factors let you compare categories by order [OK]

Common Mistakes:

• Thinking ordered factors store numeric data
• Confusing ordered factors with numeric conversion
• Believing ordered factors remove duplicates

2. Which of the following is the correct way to create an ordered factor f with levels "low" < "medium" < "high" in R?

easy

A. f <- factor(c("low", "high", "medium"), ordered=TRUE, levels=c("low", "medium", "high"))

B. f <- ordered(c("low", "high", "medium"), levels=c("high", "medium", "low"))

C. f <- factor(c("low", "high", "medium"), levels=c("high", "medium", "low"), ordered=TRUE)

D. f <- ordered(c("low", "high", "medium"))

Solution

1. Step 1: Check the function and parameters

   Using factor() with ordered=TRUE and specifying levels sets the order.

2. Step 2: Verify the levels order

   The levels must be in ascending order: "low", "medium", "high".

3. Final Answer:

   f <- factor(c("low", "high", "medium"), ordered=TRUE, levels=c("low", "medium", "high")) -> Option A

4. Quick Check:

   Correct syntax with ordered=TRUE and levels order [OK]

Hint: Use factor(..., ordered=TRUE, levels=correct_order) [OK]

Common Mistakes:

• Reversing the levels order
• Using ordered() without levels
• Setting ordered=TRUE but wrong levels order

3. What will be the output of the following R code?

f <- factor(c("small", "medium", "large"), ordered=TRUE, levels=c("small", "medium", "large"))
f > "medium"

medium

A. [FALSE FALSE FALSE]

B. [FALSE TRUE TRUE]

C. [FALSE FALSE TRUE]

D. [TRUE FALSE TRUE]

Solution

1. Step 1: Understand the factor levels and order

   The levels are "small" < "medium" < "large".

2. Step 2: Compare each element to "medium"

   "small" > "medium" is FALSE, "medium" > "medium" is FALSE, "large" > "medium" is TRUE.

3. Final Answer:

   [FALSE FALSE TRUE] -> Option C

4. Quick Check:

   Only "large" is greater than "medium" [OK]

Hint: Compare ordered factor elements to level with > operator [OK]

Common Mistakes:

• Confusing the order of levels
• Assuming equality returns TRUE
• Mixing up TRUE/FALSE positions

4. Identify the error in this R code that tries to create an ordered factor:

levels <- c("low", "medium", "high")
f <- factor(c("low", "high", "medium"), ordered=TRUE, levels=levels)

medium

A. The ordered=TRUE argument is missing

B. The levels vector is not in alphabetical order

C. The factor vector contains values not in levels

D. The variable name 'levels' conflicts with the function argument name

Solution

1. Step 1: Check variable and argument names

   Using 'levels' as a variable name shadows the function argument 'levels'.

2. Step 2: Understand the conflict

   This can cause unexpected behavior or errors because R confuses the variable with the argument.

3. Final Answer:

   The variable name 'levels' conflicts with the function argument name -> Option D

4. Quick Check:

   Variable name shadows argument name [OK]

Hint: Avoid naming variables 'levels' to prevent conflicts [OK]

Common Mistakes:

• Ignoring variable name conflicts
• Assuming alphabetical order is required
• Missing ordered=TRUE argument

5. You have a survey with responses: "Agree", "Neutral", "Disagree". You want to create an ordered factor response where "Disagree" < "Neutral" < "Agree". Which R code correctly creates this ordered factor and allows you to check if a response is at least "Neutral"?

hard

A. response <- factor(c("Agree", "Disagree", "Neutral"), ordered=TRUE, levels=c("Disagree", "Neutral", "Agree"))
response >= "Neutral"

B. response <- ordered(c("Agree", "Disagree", "Neutral"), levels=c("Agree", "Neutral", "Disagree"))
response >= "Neutral"

C. response <- factor(c("Agree", "Disagree", "Neutral"), levels=c("Disagree", "Neutral", "Agree"))
response >= "Neutral"

D. response <- ordered(c("Agree", "Disagree", "Neutral"))
response >= "Neutral"

Solution

1. Step 1: Set levels in correct order

   The levels must be "Disagree" < "Neutral" < "Agree" to reflect the survey order.

2. Step 2: Create ordered factor and compare

   Using factor(..., ordered=TRUE, levels=...) creates the ordered factor. Then, response >= "Neutral" checks if responses are at least "Neutral".

3. Final Answer:

   response <- factor(c("Agree", "Disagree", "Neutral"), ordered=TRUE, levels=c("Disagree", "Neutral", "Agree")) response >= "Neutral" -> Option A

4. Quick Check:

   Correct order and comparison with ordered factor [OK]

Hint: Set levels in order and use ordered=TRUE for comparisons [OK]

Common Mistakes:

• Wrong levels order
• Missing ordered=TRUE
• Using ordered() without levels