In R, to access the first element of a vector named vec, you would use ______.
- vec[0]
- vec[1]
- vec[1st]
- vec$first
In R, to access the first element of a vector named vec, you would use vec[1]. R uses 1-based indexing, so the index 1 refers to the first element of the vector.
In R, the median of a numeric vector is calculated using the ______ function.
- median()
- mean()
- sum()
- mode()
The median of a numeric vector in R is calculated using the median() function. The median() function returns the middle value when the vector is sorted in ascending order.
In R, a basic bar chart is created using the ______ function.
- barplot()
- plot()
- pie()
- scatterplot()
In R, a basic bar chart is created using the barplot() function. It takes a vector or matrix of numeric values as input and creates a vertical bar chart where each bar represents a category or variable.
How would you merge or join two data frames in R?
- Use the merge() function
- Use the join() function
- Use the combine() function
- Use the merge_join() function
To merge or join two data frames in R, you would use the merge() function. The merge() function combines two data frames based on common columns or row names, creating a new data frame that contains the merged data.
How do you define a function in R?
- Using the function keyword followed by the function name, input parameters, and the function body
- Using the def keyword followed by the function name, input parameters, and the function body
- Using the func keyword followed by the function name, input parameters, and the function body
- Using the define keyword followed by the function name, input parameters, and the function body
In R, a function is defined using the function keyword, followed by the function name, input parameters (if any), and the function body enclosed in curly braces {}. The function body contains the code that defines the operations to be performed by the function.
The syntax for a for loop in R is for (value in sequence) { ________ }.
- Statements
- Looping
- Iterations
- Operations
The syntax for a for loop in R is for (value in sequence) { statements }. The statements inside the curly braces will be executed for each value in the sequence during each iteration of the loop.
To print the text "Hello, world!" in R, you would use the syntax ________.
- "Hello, world!"
- echo("Hello, world!")
- print("Hello, world!")
- print(Hello, world!)
In R, to print a string or a message, the print() function is used. For instance, the syntax print("Hello, world!") will display the message "Hello, world!".
Can you describe a scenario where you would use a nested if statement in R?
- When you need to evaluate multiple conditions and perform different actions based on each condition
- When you want to optimize performance by avoiding nested if statements
- When you need to perform complex calculations with multiple if statements
- All of the above
A scenario where you would use a nested if statement in R is when you need to evaluate multiple conditions and perform different actions based on each condition. Nested if statements allow you to create more complex branching logic by evaluating multiple conditions within the same code block.
The _________ function in R helps in checking the existence of a variable or a function.
- check()
- confirm()
- exists()
- validate()
The 'exists()' function in R is used to check if a variable or a function exists in the current environment. This can be useful in debugging, to avoid errors when trying to use a non-existent variable or function.
Imagine you need to convert a character data type to a numeric data type for a large dataset. How would you approach this task in R?
- Use as.numeric() function
- Use mutate() function from dplyr
- Use rapply() function
- Use type.convert() function
We would use as.numeric() function to convert character data type to numeric. However, it's important to ensure that the character data is indeed convertible to numeric, otherwise NA's might be introduced.