R Online Test

The R Online Test uses scenario-based MCQs to evaluate candidates on their knowledge of R programming language, including their proficiency in working with data structures, control structures, functions, and data visualization using R libraries like ggplot2. The test includes a coding question to evaluate hands-on R programming skills and aims to evaluate a candidate's ability to work with R effectively for data analysis and statistical modeling.

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Screen candidates with a 40 mins test

Test duration: 40 mins

Difficulty level: Moderate

Availability: Ready to use

Questions:

8 R MCQs
1 R Coding Question

Covered skills:

Vectors

Matrices

Dataframes

CSV Handling

Linear regression

Confusion matrix

Random Forest

Analytics with R

String Manipulation

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Use the R Test to shortlist qualified candidates

The R Online Test helps recruiters and hiring managers identify qualified candidates from a pool of resumes, and helps in taking objective hiring decisions. It reduces the administrative overhead of interviewing too many candidates and saves time by filtering out unqualified candidates at the first step of the hiring process.

The test screens for the following skills that hiring managers look for in candidates:

Efficiently working with vectors
Working with matrices for data manipulation
Handling and analyzing data using dataframes
Managing CSV files and data handling
Applying linear regression models in R
Understanding and utilizing confusion matrices
Implementing random forest algorithms in R
Performing analytics tasks using R
Manipulating and transforming strings in R

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These are just a small sample from our library of 15,000+ questions. The actual questions on this R Online Test will be non-googleable.

🧐 Question
Medium Applying Functions Data frames Functions Math	Solve
Consider the following R code: This script defines a function apply_fun that calculates the mean of a vector and adds it to the standard deviation of the vector. The apply function is then used to apply this function to each column of the data frame df. What will be the value of result after the script is run?
Medium Dataframe Transform	Solve
Review the following Dataframe 'bazinga': Which of the following commands would turn it into the Dataframe shown below:
Medium Matrix Manipulation Matrices Lists	Solve
Consider the following pseudo code: What will be the state of list_of_matrices after running the script?
Easy Registration Queue Logic Queues	Solve
We want to register students for the next semester. All students have a receipt which shows the amount pending for the previous semester. A positive amount (or zero) represents that the student has paid extra fees, and a negative amount represents that they have pending fees to be paid. The students are in a queue for the registration. We want to arrange the students in a way such that the students who have a positive amount on the receipt get registered first as compared to the students who have a negative amount. We are given a queue in the form of an array containing the pending amount. For example, if the initial queue is [20, 70, -40, 30, -10], then the final queue will be [20, 70, 30, -40, -10]. Note that the sequence of students should not be changed while arranging them unless required to meet the condition. ⚠️⚠️⚠️ Note: - The first line of the input is the length of the array. The second line contains all the elements of the array. - The input is already parsed into an array of "strings" and passed to a function. You will need to convert string to integer/number type inside the function. - You need to "print" the final result (not return it) to pass the test cases. For the example discussed above, the input will be: 5 20 70 -40 30 -10 Your code needs to print the following to the standard output: 20 70 30 -40 -10
Medium Visitors Count Strings Logic	Solve
A manager hires a staff member to keep a record of the number of men, women, and children visiting the museum daily. The staff will note W if any women visit, M for men, and C for children. You need to write code that takes the string that represents the visits and prints the count of men, woman and children. The sequencing should be in decreasing order. Example: Input: WWMMWWCCC Expected Output: 4W3C2M Explanation: ‘W’ has the highest count, then ‘C’, then ‘M’. ⚠️⚠️⚠️ Note: - The input is already parsed and passed to a function. - You need to "print" the final result (not return it) to pass the test cases. - If the input is- “MMW”, then the expected output is "2M1W" since there is no ‘C’. - If any of them have the same count, the output should follow this order - M, W, C.

	🧐 Question	🔧 Skill
	Medium Applying Functions Data frames Functions Math	3 mins R	Solve
Consider the following R code: This script defines a function apply_fun that calculates the mean of a vector and adds it to the standard deviation of the vector. The apply function is then used to apply this function to each column of the data frame df. What will be the value of result after the script is run?
	Medium Dataframe Transform	3 mins R	Solve
Review the following Dataframe 'bazinga': Which of the following commands would turn it into the Dataframe shown below:
	Medium Matrix Manipulation Matrices Lists	3 mins R	Solve
Consider the following pseudo code: What will be the state of list_of_matrices after running the script?
	Easy Registration Queue Logic Queues	30 mins Coding	Solve
We want to register students for the next semester. All students have a receipt which shows the amount pending for the previous semester. A positive amount (or zero) represents that the student has paid extra fees, and a negative amount represents that they have pending fees to be paid. The students are in a queue for the registration. We want to arrange the students in a way such that the students who have a positive amount on the receipt get registered first as compared to the students who have a negative amount. We are given a queue in the form of an array containing the pending amount. For example, if the initial queue is [20, 70, -40, 30, -10], then the final queue will be [20, 70, 30, -40, -10]. Note that the sequence of students should not be changed while arranging them unless required to meet the condition. ⚠️⚠️⚠️ Note: - The first line of the input is the length of the array. The second line contains all the elements of the array. - The input is already parsed into an array of "strings" and passed to a function. You will need to convert string to integer/number type inside the function. - You need to "print" the final result (not return it) to pass the test cases. For the example discussed above, the input will be: 5 20 70 -40 30 -10 Your code needs to print the following to the standard output: 20 70 30 -40 -10
	Medium Visitors Count Strings Logic	30 mins Coding	Solve
A manager hires a staff member to keep a record of the number of men, women, and children visiting the museum daily. The staff will note W if any women visit, M for men, and C for children. You need to write code that takes the string that represents the visits and prints the count of men, woman and children. The sequencing should be in decreasing order. Example: Input: WWMMWWCCC Expected Output: 4W3C2M Explanation: ‘W’ has the highest count, then ‘C’, then ‘M’. ⚠️⚠️⚠️ Note: - The input is already parsed and passed to a function. - You need to "print" the final result (not return it) to pass the test cases. - If the input is- “MMW”, then the expected output is "2M1W" since there is no ‘C’. - If any of them have the same count, the output should follow this order - M, W, C.

	🧐 Question	🔧 Skill	💪 Difficulty	⌛ Time
	Applying Functions Data frames Functions Math	R	Medium	3 mins	Solve
Consider the following R code: This script defines a function apply_fun that calculates the mean of a vector and adds it to the standard deviation of the vector. The apply function is then used to apply this function to each column of the data frame df. What will be the value of result after the script is run?
	Dataframe Transform	R	Medium	3 mins	Solve
Review the following Dataframe 'bazinga': Which of the following commands would turn it into the Dataframe shown below:
	Matrix Manipulation Matrices Lists	R	Medium	3 mins	Solve
Consider the following pseudo code: What will be the state of list_of_matrices after running the script?
	Registration Queue Logic Queues	Coding	Easy	30 mins	Solve
We want to register students for the next semester. All students have a receipt which shows the amount pending for the previous semester. A positive amount (or zero) represents that the student has paid extra fees, and a negative amount represents that they have pending fees to be paid. The students are in a queue for the registration. We want to arrange the students in a way such that the students who have a positive amount on the receipt get registered first as compared to the students who have a negative amount. We are given a queue in the form of an array containing the pending amount. For example, if the initial queue is [20, 70, -40, 30, -10], then the final queue will be [20, 70, 30, -40, -10]. Note that the sequence of students should not be changed while arranging them unless required to meet the condition. ⚠️⚠️⚠️ Note: - The first line of the input is the length of the array. The second line contains all the elements of the array. - The input is already parsed into an array of "strings" and passed to a function. You will need to convert string to integer/number type inside the function. - You need to "print" the final result (not return it) to pass the test cases. For the example discussed above, the input will be: 5 20 70 -40 30 -10 Your code needs to print the following to the standard output: 20 70 30 -40 -10
	Visitors Count Strings Logic	Coding	Medium	30 mins	Solve
A manager hires a staff member to keep a record of the number of men, women, and children visiting the museum daily. The staff will note W if any women visit, M for men, and C for children. You need to write code that takes the string that represents the visits and prints the count of men, woman and children. The sequencing should be in decreasing order. Example: Input: WWMMWWCCC Expected Output: 4W3C2M Explanation: ‘W’ has the highest count, then ‘C’, then ‘M’. ⚠️⚠️⚠️ Note: - The input is already parsed and passed to a function. - You need to "print" the final result (not return it) to pass the test cases. - If the input is- “MMW”, then the expected output is "2M1W" since there is no ‘C’. - If any of them have the same count, the output should follow this order - M, W, C.

Test candidates on core R Hiring Test topics

Vectors: Vectors in R are one-dimensional arrays that can hold elements of any type. They are used to store and perform operations on a homogeneous set of data. Measuring this skill will assess a candidate's understanding of vector creation, indexing, and various vector operations.

Matrices: Matrices in R are two-dimensional arrays that store elements of the same type. This skill will evaluate a candidate's ability to create and manipulate matrices, perform matrix operations such as addition, subtraction, and multiplication, and apply matrix operations in solving problems.

Dataframes: Dataframes are tabular data structures in R that store data in rows and columns. Assessing a candidate's knowledge of dataframes will ascertain their proficiency in data manipulation, including merging, filtering, and transforming data, as well as their understanding of data reshaping.

CSV Handling: CSV (Comma-Separated Values) handling is the ability to read, write, and manipulate data stored in CSV format. This skill is crucial in real-life scenarios where data is often exchanged and stored in CSV files. Assessing this skill will determine a candidate's proficiency in loading, saving, and performing data transformations on CSV files in R.

Linear regression: Linear regression is a statistical technique used to analyze the relationship between a dependent variable and one or more independent variables. Measuring a candidate's understanding of linear regression will assess their ability to fit linear regression models, interpret model outputs, and make predictions using the models.

Confusion matrix: A confusion matrix is a table that represents the performance of a classification algorithm. Measuring a candidate's knowledge of confusion matrices will evaluate their understanding of key metrics such as accuracy, precision, recall, and F1 score, and their ability to analyze and interpret classification results.

Random Forest: Random Forest is an ensemble learning method used for classification and regression. Assessing this skill will gauge a candidate's ability to apply the Random Forest algorithm, understand the underlying principles, tune the model parameters, and evaluate its performance using appropriate statistical measures.

Analytics with R: Analytics with R involves using R programming language and its associated packages to perform data analysis, visualization, and statistical modeling. Evaluating this skill will determine a candidate's proficiency in utilizing R's analytical capabilities, applying statistical techniques, and generating insights from data.

String Manipulation: String manipulation refers to the process of modifying, extracting, or manipulating textual data in R. This skill assessment will measure a candidate's ability to perform tasks such as concatenating strings, replacing patterns, extracting substrings, and applying regular expressions on character data to solve data processing and manipulation challenges.

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