The practice workbook

R sticks when you write it, not when you read about it. Each problem here checks your answer the moment you run it, so you always know which skills you own and which need another rep.

Task: Keep only the values greater than 10, then return their mean.

RYour turn
x <- c(4, 19, 7, 42, 23)
 
Start with R Beginner Exercises 13 of 30 problems are beginner level. A gentle first set in R Fundamentals. Free, no account needed.
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R Interview Questions (Top 50) The 50 problems interviewers actually ask, from vector gotchas to model output. All auto-graded.
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The Exercises Wall

unsolved solved, in its topic color +10 to +50 XP per problem

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R Fundamentals

#>18 hubs · 397 problems · 0/397 solved · 10,855 XP

Vectors, data frames, functions, and the base R muscle memory everything else builds on.

HubDifficultyDoneXP
1.1 R Beginner Exercises 13152 30 605 XP
1.2 R apply Family 6104 20 510 XP
1.3 R Lists 7134 24 595 XP
1.4 R for Data Science Exercises 12317 50 1,245 XP
1.5 R Data Frames 494 17 465 XP
1.6 Functional Programming 4104 18 490 XP
1.7 R Vectors 4104 18 490 XP
1.8 R Control Flow 495 18 515 XP
1.9 R Date & Time 4124 20 540 XP
1.10 OOP in R 4106 20 590 XP
1.11 R Subsetting 4106 20 590 XP
1.12 purrr Exercises 5178 30 875 XP
1.13 R Basics 3105 18 530 XP
1.14 R Functions 3105 18 530 XP
1.15 R Debugging Exercises 387 18 580 XP
1.16 Apply Family Exercises 3125 20 580 XP
1.17 Loops vs Vectorization Exercises 3125 20 580 XP
1.18 R Strings 2115 18 545 XP
Finished here? Take the R Fundamentals Quiz (12 min) and bank credit toward the certificate.Start quiz
Finished here? Take the Functional Programming Quiz (12 min) and bank credit toward the certificate.Start quiz
Finished here? Take the R Interview Readiness Quiz (12 min) and bank credit toward the certificate.Start quiz

Data Wrangling

#>29 hubs · 738 problems · 0/738 solved · 21,485 XP

Import, clean, reshape, and join real datasets with dplyr, tidyr, and friends.

HubDifficultyDoneXP
2.1 dplyr 555 15 425 XP
2.2 Tidyverse Exercises 142214 50 1,390 XP
2.3 Data Import 494 17 465 XP
2.4 API Calls Exercises 476 17 515 XP
2.5 purrr 346 13 430 XP
2.6 Missing Data in R 496 19 565 XP
2.7 dplyr filter() & select() 4133 20 515 XP
2.8 data.table 4124 20 540 XP
2.9 dbplyr / SQL Exercises 4115 20 565 XP
2.10 Regex Exercises 5137 25 725 XP
2.11 data.table Exercises 102614 50 1,450 XP
2.12 dplyr Window Functions Exercises 5137 25 725 XP
2.13 lubridate Exercises 5176 28 775 XP
2.14 stringr Exercises 5176 28 775 XP
2.15 readr Exercises 5167 28 800 XP
2.16 Data Cleaning Exercises 5158 28 825 XP
2.17 Web Scraping Exercises 395 17 505 XP
2.18 tidyr Reshaping 3123 18 480 XP
2.19 tidyr Pivot Exercises 3114 18 505 XP
2.20 Date-Time Manipulation Exercises 3105 18 530 XP
2.21 tidyr Exercises 5169 30 900 XP
2.22 Data Wrangling Exercises 83012 50 1,430 XP
2.23 dplyr Exercises 83012 50 1,430 XP
2.24 dplyr Joins 3116 20 605 XP
2.25 forcats Exercises 41410 28 890 XP
2.26 dplyr group_by Exercises 3157 25 755 XP
2.27 dplyr Joins Exercises 3139 25 805 XP
2.28 dplyr group_by() & summarise() 2106 18 570 XP
2.29 tidyr Nest/Unnest Exercises 297 18 595 XP
Finished here? Take the dplyr Quiz (12 min) and bank credit toward the certificate.Start quiz
Finished here? Take the tidyr Quiz (12 min) and bank credit toward the certificate.Start quiz

Visualization

#>16 hubs · 395 problems · 0/395 solved · 11,800 XP

Charts that read clearly, from a first ggplot2 bar chart to themed, faceted figures.

HubDifficultyDoneXP
3.1 ggplot2 555 15 425 XP
3.2 ggplot2 Themes Exercises 5114 20 525 XP
3.3 EDA Exercises 112910 50 1,335 XP
3.4 ggplot2 Heatmap Exercises 4115 20 565 XP
3.5 ggplot2 Facets 375 15 455 XP
3.6 ggplot2 Color Scales Exercises 497 20 615 XP
3.7 leaflet Exercises 497 20 615 XP
3.8 ggplot2 Geoms 394 16 455 XP
3.9 ggplot2 Exercises 92714 50 1,465 XP
3.10 ggplot2 Aesthetics 3105 18 530 XP
3.11 Data Viz Exercises 4147 25 740 XP
3.12 ggplot2 Facets Exercises 3125 20 580 XP
3.13 plotly Exercises 3107 20 630 XP
3.14 ggplot2 Bar Chart Exercises 2106 18 570 XP
3.15 ggplot2 Customization 2106 18 570 XP
3.16 R Visualization Project (5 charts) 52322 50 1,725 XP
Finished here? Take the ggplot2 Quiz (12 min) and bank credit toward the certificate.Start quiz

Statistics

#>37 hubs · 743 problems · 0/743 solved · 22,375 XP

Probability, tests, confidence intervals, and regression, practiced until the output makes sense.

HubDifficultyDoneXP
4.1 Probability in R Exercises 465 15 440 XP
4.2 Probability Distributions 6136 25 685 XP
4.3 Mixed Effects Exercises 459 18 615 XP
4.4 A/B Testing Exercises 4124 20 540 XP
4.5 ANOVA Exercises 393 15 405 XP
4.6 Linear Regression 103010 50 1,350 XP
4.7 Chi-Square Exercises 4115 20 565 XP
4.8 t-Test Exercises 4115 20 565 XP
4.9 R Probability Distributions 4106 20 590 XP
4.10 Experimental Design Exercises 497 20 615 XP
4.11 Binomial Distribution Exercises 3104 17 480 XP
4.12 Confidence Interval 3123 18 480 XP
4.13 Nonparametric Exercises 3114 18 505 XP
4.14 Multiple Testing 3105 18 530 XP
4.15 A/B Testing Exercises 396 18 555 XP
4.16 Power Analysis Exercises 387 18 580 XP
4.17 Correlation Exercises 3125 20 580 XP
4.18 Poisson Regression 3125 20 580 XP
4.19 Sampling Methods Exercises 3125 20 580 XP
4.20 Survey Analysis Exercises 3116 20 605 XP
4.21 broom Exercises 3116 20 605 XP
4.22 PCA Exercises 3107 20 630 XP
4.23 GLM Exercises 3118 22 705 XP
4.24 Central Limit Theorem Exercises 2104 16 470 XP
4.25 SEM Exercises 268 16 570 XP
4.26 Logistic Regression Exercises 3157 25 755 XP
4.27 Regression Diagnostics Exercises 3157 25 755 XP
4.28 Hypothesis Testing Exercises 3148 25 780 XP
4.29 Clustering Exercises 2114 17 495 XP
4.30 Poisson Distribution Exercises 2105 17 520 XP
4.31 Ridge & Lasso Exercises 2115 18 545 XP
4.32 Post-Hoc Tests Exercises 2106 18 570 XP
4.33 Survival Analysis Exercises 2106 18 570 XP
4.34 Bayesian Statistics Exercises 2108 20 670 XP
4.35 Multiple Regression Exercises 2118 21 695 XP
4.36 Repeated Measures 1106 17 560 XP
4.37 GAM Exercises 198 18 635 XP
Finished here? Take the Hypothesis Testing Quiz (12 min) and bank credit toward the certificate.Start quiz
Finished here? Take the Linear Regression Quiz (12 min) and bank credit toward the certificate.Start quiz

Time Series

#>2 hubs · 55 problems · 0/55 solved · 1,605 XP

Dates, decomposition, and ARIMA forecasting drills.

HubDifficultyDoneXP
5.1 Time Series Exercises 6177 30 835 XP
5.2 ARIMA Exercises 2167 25 770 XP
Finished here? Take the Time Series Quiz (12 min) and bank credit toward the certificate.Start quiz

Machine Learning

#>8 hubs · 194 problems · 0/194 solved · 5,850 XP

Train, validate, and tune models: trees, forests, boosting, clustering.

HubDifficultyDoneXP
6.1 Machine Learning Exercises 132314 50 1,405 XP
6.2 Decision Tree Exercises 4104 18 490 XP
6.3 XGBoost Exercises 4106 20 590 XP
6.4 tidymodels Exercises 4129 25 790 XP
6.5 Random Forest Exercises 3125 20 580 XP
6.6 caret Exercises 3126 21 630 XP
6.7 Clustering Exercises 2108 20 670 XP
6.8 Cross Validation Exercises 299 20 695 XP
Finished here? Take the Machine Learning Quiz (12 min) and bank credit toward the certificate.Start quiz

Advanced R

#>5 hubs · 105 problems · 0/105 solved · 3,190 XP

Performance, packages, testing, and Shiny apps.

HubDifficultyDoneXP
7.1 Parallel Computing Exercises 6107 23 660 XP
7.2 R Performance Exercises 4115 20 565 XP
7.3 testthat Exercises 3104 17 480 XP
7.4 R Package Development 3107 20 630 XP
7.5 Shiny Exercises 31111 25 855 XP
Finished here? Take the Shiny Quiz (12 min) and bank credit toward the certificate.Start quiz

Reporting

#>2 hubs · 48 problems · 0/48 solved · 1,350 XP

R Markdown documents and publication tables.

HubDifficultyDoneXP
8.1 gt Tables Exercises 5126 23 650 XP
8.2 R Markdown Exercises 5146 25 700 XP

Specializations

#>9 hubs · 179 problems · 0/179 solved · 5,925 XP

Domain practice: finance, genomics, healthcare, marketing, spatial, text.

HubDifficultyDoneXP
9.1 Network Analysis Exercises 4115 20 565 XP
9.2 R for Biostatistics 497 20 615 XP
9.3 R for Healthcare Exercises 479 20 665 XP
9.4 R for Finance Exercises 5713 25 875 XP
9.5 Text Mining Exercises 3107 20 630 XP
9.6 R for Sports Analytics 389 20 680 XP
9.7 R for Marketing Analytics 3611 20 730 XP
9.8 Spatial Analysis Exercises 285 15 470 XP
9.9 R for Genomics 2710 19 695 XP

Mastery quizzes

#>11 assessments · timed · count toward the certificate

Each quiz also appears at the end of its topic above. Pass one and it counts toward the certificate.

R Fundamentals Quiz dplyr Quiz ggplot2 Quiz Hypothesis Testing Quiz Linear Regression Quiz Machine Learning Quiz tidyr Quiz Time Series Quiz Shiny Quiz R Interview Readiness Quiz Functional Programming Quiz

Keep what you earn

Attempts are free without an account. Sign in and every solve, streak day, and XP point is saved to your profile, and finished topics count toward the certificate.

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