Type checking and conversion in R Programming - Interactive Code Practice

Practice - 5 Tasks

1fill in blank

easy

Complete the code to check if the variable x is numeric.

R Programming

is_numeric <- is[1](x)

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

Anumeric

Attempts:

3 left

💡 Hint

Common Mistakes

Using is.integer() instead of is.numeric()

Using typeof() instead of is.numeric()

The function is.numeric() checks if a variable is numeric in R.

2fill in blank

medium

Complete the code to convert the variable y to a character type.

R Programming

y_char <- as[1](y)

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Anumeric

Bcharacter

Clogical

Dinteger

Attempts:

3 left

💡 Hint

Common Mistakes

Using as.numeric() instead of as.character()

Using as.logical() instead of as.character()

The function as.character() converts a variable to character type in R.

3fill in blank

hard

Fix the error in the code to check if z is a logical type.

R Programming

is_logical <- is[1](z)

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

Alogical

Bnumeric

Ccharacter

Dinteger

Attempts:

3 left

💡 Hint

Common Mistakes

Using is.numeric() instead of is.logical()

Using is.character() instead of is.logical()

The correct function to check logical type is is.logical().

4fill in blank

hard

Fill both blanks to create a named vector with names as characters and values as numeric.

R Programming

vec <- c([1] = 1, [2] = 2)

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A"a"

B"1"

C"b"

D"2"

Attempts:

3 left

💡 Hint

Common Mistakes

Using numbers as names without quotes

Using unquoted names

Vector names must be character strings, so use quotes around letters.

5fill in blank

hard

Fill all three blanks to create a list with a numeric, a character, and a logical element.

R Programming

my_list <- list(num = [1], char = [2], logi = [3])

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A42

B"hello"

CTRUE

DFALSE

Attempts:

3 left

💡 Hint

Common Mistakes

Putting numbers inside quotes for numeric

Using FALSE instead of TRUE for logical

The list elements are numeric (42), character ("hello"), and logical (TRUE).

Practice

1. Which function in R checks if a variable is of numeric type?

easy

A. as.character()

B. as.numeric()

C. is.character()

D. is.numeric()

Solution

1. Step 1: Understand type checking functions

   Functions starting with is. check the type of a variable.

2. Step 2: Identify the correct function for numeric check

   is.numeric() returns TRUE if the variable is numeric.

3. Final Answer:

   is.numeric() -> Option D

4. Quick Check:

   Type check numeric = is.numeric() [OK]

Hint: Use is.type() to check type, as.type() to convert [OK]

Common Mistakes:

• Confusing is.numeric() with as.numeric()
• Using as.character() to check type
• Using is.character() for numeric check

2. Which of the following is the correct way to convert a character vector c("1", "2", "3") to numeric in R?

easy

A. is.numeric(c("1", "2", "3"))

B. as.numeric(c("1", "2", "3"))

C. as.character(c(1, 2, 3))

D. is.character(c(1, 2, 3))

Solution

1. Step 1: Identify conversion functions

   as.numeric() converts data to numeric type.

2. Step 2: Apply conversion to character vector

   Using as.numeric(c("1", "2", "3")) converts strings to numbers 1, 2, 3.

3. Final Answer:

   as.numeric(c("1", "2", "3")) -> Option B

4. Quick Check:

   Convert char to numeric = as.numeric() [OK]

Hint: Use as.numeric() to convert strings to numbers [OK]

Common Mistakes:

• Using is.numeric() instead of as.numeric()
• Trying to convert numeric to character for numeric conversion
• Confusing is.character() with conversion functions

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

vec <- c("10", "20", "30")
num_vec <- as.numeric(vec)
is.numeric(num_vec)

medium

A. TRUE

B. FALSE

C. Error

D. NA

Solution

1. Step 1: Convert character vector to numeric

   as.numeric(vec) changes strings "10", "20", "30" to numbers 10, 20, 30.

2. Step 2: Check if converted vector is numeric

   is.numeric(num_vec) returns TRUE because num_vec is numeric.

3. Final Answer:

   TRUE -> Option A

4. Quick Check:

   as.numeric() converts, is.numeric() confirms [OK]

Hint: as.numeric() converts, is.numeric() checks type [OK]

Common Mistakes:

• Expecting FALSE because original was character
• Thinking as.numeric() returns character
• Confusing is.numeric() with as.numeric()

4. Identify the error in the following R code snippet:

val <- "123abc"
num_val <- as.numeric(val)
print(num_val)

medium

A. No error, prints 123

B. Syntax error due to quotes

C. Prints NA with a warning

D. Prints 0 without warning

Solution

1. Step 1: Attempt to convert mixed string to numeric

   as.numeric("123abc") cannot convert because of non-numeric characters.

2. Step 2: Result of conversion

   It returns NA and shows a warning about NAs introduced by coercion.

3. Final Answer:

   Prints NA with a warning -> Option C

4. Quick Check:

   Invalid numeric conversion = NA + warning [OK]

Hint: Invalid numeric strings convert to NA with warning [OK]

Common Mistakes:

• Expecting partial numeric conversion
• Ignoring warning messages
• Assuming syntax error due to quotes

5. You have a list lst <- list("5", 10, "abc", "15.5"). Which R code correctly converts all elements to numeric, replacing non-convertible values with 0?

hard

A. sapply(lst, function(x) if(is.na(as.numeric(x))) 0 else as.numeric(x))

B. sapply(lst, function(x) as.numeric(x))

C. sapply(lst, function(x) if(is.na(as.numeric(x))) as.numeric(x) else 0)

D. sapply(lst, function(x) if(is.numeric(x)) x else 0)

Solution

1. Step 1: Convert each element to numeric and check for NA

   Use as.numeric(x) inside a function and check if result is NA.

2. Step 2: Replace NA with 0, else keep numeric value

   If as.numeric(x) is NA, return 0; otherwise return the numeric value.

3. Final Answer:

   sapply(lst, function(x) if(is.na(as.numeric(x))) 0 else as.numeric(x)) -> Option A

4. Quick Check:

   Replace NA with 0 using conditional inside sapply [OK]

Hint: Use is.na(as.numeric(x)) to detect and replace [OK]

Common Mistakes:

• Not checking for NA after conversion
• Replacing numeric values incorrectly
• Confusing condition logic in if-else