Labels and titles in R Programming - Mini Project: Build & Apply

Labels and titles

📖 Scenario: You are creating a simple plot to show the relationship between two variables in a dataset. To make the plot clear and easy to understand, you need to add labels to the axes and a title to the plot.

🎯 Goal: Build a basic scatter plot with proper axis labels and a main title using R.

📋 What You'll Learn

Create vectors for x and y data

Create variables for x-axis label, y-axis label, and plot title

Use the plot() function with labels and title

Print the plot with the correct labels and title

💡 Why This Matters

🌍 Real World

Adding clear labels and titles to graphs helps people understand data quickly, like in reports or presentations.

💼 Career

Data analysts and scientists often create plots with labels and titles to communicate insights clearly.

1

Create data vectors

Create two numeric vectors called x and y with these exact values: x = c(1, 2, 3, 4, 5) and y = c(2, 4, 6, 8, 10).

R Programming

# Create vectors x and y with the given values
# Your code here

Hint

Use the c() function to create vectors in R.

2

Create label variables

Create three variables: x_label with value "X Axis", y_label with value "Y Axis", and main_title with value "Simple Scatter Plot".

R Programming

x <- c(1, 2, 3, 4, 5)
y <- c(2, 4, 6, 8, 10)
# Create x_label, y_label, and main_title variables
# Your code here

Hint

Assign strings to variables using the <- operator.

3

Create the plot with labels and title

Use the plot() function with x and y as data, and add the labels using xlab = x_label, ylab = y_label, and main = main_title.

R Programming

x <- c(1, 2, 3, 4, 5)
y <- c(2, 4, 6, 8, 10)
x_label <- "X Axis"
y_label <- "Y Axis"
main_title <- "Simple Scatter Plot"
# Use plot() with x, y, xlab, ylab, and main
# Your code here

Hint

The plot() function can take xlab, ylab, and main arguments for labels and title.

4

Display the plot

Run the code to display the scatter plot with the correct labels and title.

R Programming

x <- c(1, 2, 3, 4, 5)
y <- c(2, 4, 6, 8, 10)
x_label <- "X Axis"
y_label <- "Y Axis"
main_title <- "Simple Scatter Plot"
plot(x, y, xlab = x_label, ylab = y_label, main = main_title)
# Run the code to show the plot
# Your code here

Hint

Just run the code to see the plot with labels and title.

Practice

1. What is the purpose of using main in an R plot?

easy

A. To add a main title to the plot

B. To label the x-axis

C. To label the y-axis

D. To change the plot color

Solution

1. Step 1: Understand the role of main in plotting

   The main argument in R's plot function is used to set the main title of the graph.

2. Step 2: Differentiate from axis labels

   xlab and ylab are used for x-axis and y-axis labels respectively, not main.

3. Final Answer:

   To add a main title to the plot -> Option A

4. Quick Check:

   main = main title [OK]

Hint: Remember: main = title, xlab = x-axis, ylab = y-axis [OK]

Common Mistakes:

• Confusing main with axis labels
• Using main to change colors
• Omitting labels entirely

2. Which of the following is the correct syntax to add a y-axis label "Height" in an R plot?

easy

A. plot(x, y, xlab = "Height")

B. plot(x, y, ylab = "Height")

C. plot(x, y, main = "Height")

D. plot(x, y, label = "Height")

Solution

1. Step 1: Identify the argument for y-axis label

   In R, ylab is used to set the label for the y-axis.

2. Step 2: Check the syntax correctness

   The syntax plot(x, y, ylab = "Height") correctly assigns "Height" as the y-axis label.

3. Final Answer:

   plot(x, y, ylab = "Height") -> Option B

4. Quick Check:

   ylab = y-axis label [OK]

Hint: Use ylab for y-axis label inside plot() [OK]

Common Mistakes:

• Using main instead of ylab for y-axis label
• Using xlab for y-axis label
• Using a non-existent label argument

3. What will be the main title of the plot after running this code?

plot(1:5, 1:5, main = "Sales Over Time", xlab = "Month", ylab = "Sales")

medium

A. Month

B. No title

C. Sales

D. Sales Over Time

Solution

1. Step 1: Identify the main title argument

   The argument main = "Sales Over Time" sets the main title of the plot.

2. Step 2: Confirm other labels are axis labels

   xlab = "Month" and ylab = "Sales" set the x-axis and y-axis labels, not the main title.

3. Final Answer:

   Sales Over Time -> Option D

4. Quick Check:

   main = "Sales Over Time" [OK]

Hint: main sets the plot title, not axis labels [OK]

Common Mistakes:

• Confusing xlab or ylab as main title
• Ignoring the main argument
• Assuming no title if not obvious

4. Identify the error in this R plot code:

plot(x, y, main = "Data", xlabel = "Time", ylab = "Value")

medium

A. The argument 'xlabel' is incorrect; it should be 'xlab'

B. The argument 'main' should be 'title'

C. The argument 'ylab' should be 'ylabel'

D. There is no error in the code

Solution

1. Step 1: Check the axis label arguments

   In R, the correct argument for x-axis label is xlab, not xlabel.

2. Step 2: Verify other arguments

   main is correct for the title, and ylab is correct for y-axis label.

3. Final Answer:

   The argument 'xlabel' is incorrect; it should be 'xlab' -> Option A

4. Quick Check:

   Use xlab, not xlabel [OK]

Hint: Use xlab and ylab, not xlabel or ylabel [OK]

Common Mistakes:

• Using xlabel instead of xlab
• Using ylabel instead of ylab
• Changing main to title incorrectly

5. You want to create a plot with the main title "Temperature Trends", x-axis label "Year", and y-axis label "Temperature (°C)". Which code correctly achieves this?

hard

A. plot(years, temps, main = "Temperature Trends", xlab = "Year")

B. plot(years, temps, title = "Temperature Trends", xlabel = "Year", ylabel = "Temperature (°C)")

C. plot(years, temps, main = "Temperature Trends", xlab = "Year", ylab = "Temperature (°C)")

D. plot(years, temps, main = "Temperature Trends", xlabel = "Year", ylab = "Temperature (°C)")

Solution

1. Step 1: Use correct arguments for labels and title

   The correct arguments are main for the title, xlab for the x-axis label, and ylab for the y-axis label.

2. Step 2: Check each option for correctness

   plot(years, temps, main = "Temperature Trends", xlab = "Year", ylab = "Temperature (°C)") uses all correct arguments. plot(years, temps, title = "Temperature Trends", xlabel = "Year", ylabel = "Temperature (°C)") uses incorrect argument names. plot(years, temps, main = "Temperature Trends", xlabel = "Year", ylab = "Temperature (°C)") uses incorrect xlabel. plot(years, temps, main = "Temperature Trends", xlab = "Year") misses the y-axis label.

3. Final Answer:

   plot(years, temps, main = "Temperature Trends", xlab = "Year", ylab = "Temperature (°C)") -> Option C

4. Quick Check:

   main, xlab, ylab = correct labels [OK]

Hint: Always use main, xlab, ylab for titles and axis labels [OK]

Common Mistakes:

• Using title instead of main
• Using xlabel or ylabel instead of xlab or ylab
• Forgetting one of the labels