R Programming Language

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Coding
Theory
Quiz

    Data Wrangling Transformation

    • Categorical Frequency Table

      Junior
    • Subset Data Frames by Conditions

      Junior
    • Row of Maximum With which()

      Junior
    • Deduplicating Data Frames With duplicated()

      Junior
    • Inner Join Two Data Frames by ID

      Mid
    • Sales Summaries With dplyr Pipes

      Mid
    • dplyr Wrangling Helpers

      Mid
    • Data Frame Join Functions

      Mid
    • Wide/Long Reshaping With tidyr Pivots

      Mid
    • Drop and Count NA Rows

      Mid
    • Average Order Value Per Customer

      Mid
    • Grouped Stats and Share with dplyr

      Mid
    • Per-Category Cumulative Counts and Sums

      Mid

    Data Frame Basics

    • Remove Columns From a Data Frame

      Junior
    • Add Columns to a Data Frame

      Junior
    • Conditional Comparison Columns

      Junior
    • Derive Order Columns From Price And Quantity

      Junior
    • Transpose Matrices and Data Frames

      Junior
    • Combine Data Frames by Columns and Rows

      Junior
    • Rename Columns With dplyr

      Junior
    • Data Frame Structure Summary

      Junior
    • Row-Binding Data Frames With bind_rows()

      Mid

    Data Types Structures

    • Data Frame Builder Functions

      Junior
    • Sequence Building Helpers

      Junior
    • Base R Data Types Toolkit

      Junior
    • Type Conversion Helpers in Base R

      Junior
    • Vector Creation and Stats

      Junior
    • Stack Two 3x3 Matrices Into an Array

      Junior
    • Mixed-Type List Helpers

      Junior
    • Build a 3x3 Integer Matrix

      Junior
    • R Data Structures and List Access

      Junior
    • Sequence Sub-Range Statistics

      Junior

    Missing Values Data Cleaning

    • Missing Value Helpers in R

      Junior
    • Coalesce Columns Row-Wise

      Mid
    • Row-wise Maximum With NA Handling

      Mid
    • Dataset Cleaning Pipeline in Base R

      Mid
    • Standardize Contact Text Formats

      Mid
    • Dataset Quality Validation Functions

      Mid

    Visualization Plotting

    • Correlation Matrix and Long Form

      Junior
    • IQR Outlier Detection Toolkit

      Mid

    Functions Functional Programming

    • Matrix Aggregations With apply()

      Junior
    • Element-Wise add_numbers Function

      Junior
    • Weighted Group Summary and Winsorized Mean

      Mid
    • Functional Helpers With apply/map

      Mid
    • Closure Function Factories

      Mid
    • purrr map2 and pmap Iteration

      Mid
    • Functional Folds With Reduce and Filter

      Mid
    • Variadic Functions Forwarding With ...

      Mid
    • Dynamic Invocation With do.call

      Mid

    Performance Parallelism

    • Type-Safe Grouped Summaries With tapply and vapply

      Junior
    • Vectorize a Slow Group-Stats Script

      Senior
    • Update Joins With data.table :=

      Senior

    Text Strings Dates

    • Concatenate Strings in R

      Junior
    • Clean Text Columns With stringr

      Junior
    • Parse Messy Date Strings

      Mid
    • Extract Structured Data From Text

      Mid
    • Regex Extraction and Replacement Helpers

      Mid
    • Date and Time Zone Helpers With lubridate

      Mid
    • Factor Wrangling With forcats

      Mid

    Time Series Forecasting

    • Seasonal Sales Analysis in R

      Mid
    • Seasonal Time Series Forecasting

      Mid
    • Stationarity Transforms on EuStockMarkets

      Senior
    • Baseline Time Series Forecasting Toolkit

      Senior

    Import Export File Io

    • Reading CSV Data in Base R

      Junior
    • Write Data Frame to CSV

      Junior
    • Bind CSV Directory Into One Data Frame

      Junior
    • data.table Grouped Sales Aggregation

      Mid

    Statistical Analysis

    • Welch Two-Group T-Test

      Mid
    • Chi-Square Test of Independence

      Mid
    • One-Way ANOVA With Tukey Post-Hoc

      Mid
    • PCA From Scratch With SVD

      Senior

    Regression Modeling

    • Train/Validation Split (70/30)

      Junior
    • Reproducible Stratified Sampling

      Junior
    • Interaction Model With Durbin-Watson

      Senior
    • Logistic Regression With Stepwise Selection

      Senior

    R Language Features Workflows

    • Reproduce Base R Vector Semantics

      Junior
    • Fix Four Buggy R Routines

      Mid
    • R Expression to Prefix Notation

      Mid
    • Testthat Unit Tests for R Utilities

      Mid
    • Graceful Error Handling With tryCatch

      Mid
    • S3 dataset Class With print and summary

      Mid
    • K-Means Clustering and Summary

      Mid
    • Build and Evaluate Expressions With quote/substitute/eval

      Senior
    • Custom Condition With withCallingHandlers

      Senior
    • S4 Rational Number Class

      Senior
    • Tidy-Eval Helpers With Bare Column Names

      Senior