Character (string) type in R Programming - Mini Project: Build & Apply

Working with Character (string) Type in R

📖 Scenario: You are creating a simple program to store and display names of fruits. This will help you understand how to work with character (string) data in R.

🎯 Goal: Build a small R script that stores fruit names as strings, counts how many fruits are in the list, extracts a specific fruit, and prints the results.

📋 What You'll Learn

Create a character vector with exact fruit names

Create a variable to store the number of fruits

Extract a specific fruit from the vector

Print the number of fruits and the extracted fruit

💡 Why This Matters

🌍 Real World

Working with character data is common when handling names, labels, or any text information in data analysis or software.

💼 Career

Knowing how to store and manipulate strings is essential for data cleaning, reporting, and user interface programming.

1

Create a character vector of fruits

Create a character vector called fruits with these exact values: "apple", "banana", "cherry", "date", "elderberry".

R Programming

# Create a character vector called fruits with the given fruit names
# Your code here

Hint

Use the c() function to combine strings into a vector.

2

Count the number of fruits

Create a variable called num_fruits that stores the number of elements in the fruits vector using the length() function.

R Programming

fruits <- c("apple", "banana", "cherry", "date", "elderberry")
# Create num_fruits to store the count of fruits
# Your code here

Hint

Use length(fruits) to find how many fruits are in the vector.

3

Extract a specific fruit

Create a variable called second_fruit that stores the second fruit in the fruits vector using indexing.

R Programming

fruits <- c("apple", "banana", "cherry", "date", "elderberry")
num_fruits <- length(fruits)
# Extract the second fruit and store it in second_fruit
# Your code here

Hint

Use square brackets [] to get the second item from the vector.

4

Print the results

Print the number of fruits using print(num_fruits) and print the second fruit using print(second_fruit).

R Programming

fruits <- c("apple", "banana", "cherry", "date", "elderberry")
num_fruits <- length(fruits)
second_fruit <- fruits[2]
# Print num_fruits and second_fruit
# Your code here

Hint

Use print() to show the values on the screen.

Practice

1. What is the correct way to create a character string in R?

easy

A. Using quotes like "hello"

B. Using parentheses like (hello)

C. Using square brackets like [hello]

D. Using curly braces like {hello}

Solution

1. Step 1: Understand character string syntax in R

   Character strings must be enclosed in quotes, either single or double.

2. Step 2: Identify the correct option

   Only Using quotes like "hello" uses quotes correctly to create a character string.

3. Final Answer:

   Using quotes like "hello" -> Option A

4. Quick Check:

   Character strings = text inside quotes [OK]

Hint: Remember: text strings always go inside quotes [OK]

Common Mistakes:

• Using parentheses instead of quotes
• Forgetting to use quotes around text
• Using brackets or braces which are not for strings

2. Which of the following is the correct syntax to join two strings "Hello" and "World" in R?

easy

A. paste("Hello", "World")

B. join("Hello", "World")

C. concat("Hello", "World")

D. combine("Hello", "World")

Solution

1. Step 1: Recall string joining function in R

   In R, paste() is used to join strings with a space by default.

2. Step 2: Check the options

   Only paste("Hello", "World") uses the correct function paste() to join strings.

3. Final Answer:

   paste("Hello", "World") -> Option A

4. Quick Check:

   Use paste() to join strings [OK]

Hint: Use paste() to combine strings with spaces [OK]

Common Mistakes:

• Using non-existent functions like join or concat
• Forgetting quotes around strings
• Using functions that do not exist in base R

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

text <- "R is fun"
substr(text, 1, 3)

medium

A. "R is fun"

B. "R i"

C. "R is"

D. "is f"

Solution

1. Step 1: Understand substr() function

   substr(text, start, stop) extracts substring from position start to stop inclusive.

2. Step 2: Apply to given code

   Positions 1 to 3 in "R is fun" are "R", " ", and "i" which combine to "R i" but note the space is counted as a character.

3. Step 3: Check actual substring

   Positions 1 to 3 are characters: 'R' (1), ' ' (2), 'i' (3), so substring is "R i".

4. Final Answer:

   "R i" -> Option B

5. Quick Check:

   substr() extracts characters by position [OK]

Hint: Count characters including spaces for substr() [OK]

Common Mistakes:

• Ignoring spaces as characters
• Confusing substr() with substring() behavior
• Off-by-one errors in positions

4. Identify the error in this R code that tries to create a character vector:

words <- c(hello, "world", "R")

medium

A. Extra comma after hello

B. Using c() instead of paste()

C. Wrong function name, should be concat()

D. Missing quotes around hello

Solution

1. Step 1: Check each element in the vector

   All elements must be character strings with quotes, but hello is unquoted.

2. Step 2: Identify the error

   Missing quotes around hello causes R to look for a variable named hello, which likely does not exist.

3. Final Answer:

   Missing quotes around hello -> Option D

4. Quick Check:

   Character strings need quotes [OK]

Hint: Always quote text inside c() for character vectors [OK]

Common Mistakes:

• Forgetting quotes around text
• Confusing c() with paste() for vectors
• Assuming c() concatenates strings without quotes

5. You have a vector of words c("apple", "banana", "cherry"). How do you create a single character string with these words separated by commas and a space, like "apple, banana, cherry"?

hard

A. paste0(c("apple", "banana", "cherry"), collapse=",")

B. paste(c("apple", "banana", "cherry"), sep=",")

C. paste(c("apple", "banana", "cherry"), collapse=", ")

D. paste0(c("apple", "banana", "cherry"), sep=",")

Solution

1. Step 1: Understand paste() with collapse

   The collapse argument joins vector elements into one string separated by the given string.

2. Step 2: Check the options

   paste(c("apple", "banana", "cherry"), collapse=", ") correctly uses paste() with collapse=", " to join words with comma and space.

3. Step 3: Why not sep?

   sep controls separator between arguments, not vector elements; collapse is needed here.

4. Final Answer:

   paste(c("apple", "banana", "cherry"), collapse=", ") -> Option C

5. Quick Check:

   Use collapse to join vector elements [OK]

Hint: Use collapse in paste() to join vector elements [OK]

Common Mistakes:

• Using sep instead of collapse
• Using paste0 which does not add separators
• Not quoting the separator string