4 Good coding practice

🎯 Learning goals

After working through Tutorial 4, you’ll be able to…

• explain the difference between Base R and the tidyverse
• explain and apply good coding practices

Now that we understand different approaches to writing R code, we focus on how to write code that is clear, readable, and easy to maintain.

1. Base R vs. tidyverse

When working with R, you will often encounter two main approaches to writing code:

• Base R
• the tidyverse

Both approaches are valid and widely used (see this overview for a comparison). Understanding the difference helps you read other people’s code and develop a consistent coding style yourself.

1.1 Base R

Base R includes all functions that are available immediately after installing R. You do not need to install additional packages to use Base R functionality.

Many online examples, older tutorials, and forum discussions use Base R. For this reason, it is useful to recognize Base R syntax even if you do not primarily use it yourself.

1.2 The tidyverse

The tidyverse is a collection of additional packages designed for data science workflows. It was developed by Hadley Wickham and collaborators at Posit (formerly RStudio).

The tidyverse provides:

• consistent function naming
• readable and structured workflows
• tools for data import, transformation, visualization, and analysis
• a shared philosophy for organizing data and code

Many beginners find tidyverse code easier to read because commands follow a consistent style. In this course, we follow the tidyverse style guide. In practice, most R users learn to read both styles but typically choose one main style within a project to keep code consistent.

2. Coding style

Writing code that works is important — but writing code that is readable and understandable is just as important. This is called good coding style.

Or, as Wickham et al. (2025) put it “Good coding style is like correct punctuation: you can manage without it, butitsuremakesthingseasiertoread.”

Good coding style helps you:

• understand your own code later,
• find and fix errors more easily,
• collaborate with others,
• make your analyses reproducible.

2.1 Use clear object names

Choose names that describe what the object contains.

Good examples ✅ :

student_age
survey_data
mean_income

Avoid unclear names like 🛑:

x
data1
temp

2.2 Use a consistent naming convention style

Names for objects or functions cannot contain blank spaces. Please also avoid special signs (e.g., ! or ?). Apart from these, a few naming convention styles exist:

• snake_case 🐍: words are separated using an underscore _. This is the preferred naming style in the tidyverse and the main style used in this course. Example: data_survey.

• ant.case: words are separated using a dot .. This style appears frequently in Base R scripts. Example: data.survey.

• camelCase: each new word starts with a capital letter (except the first word). This style appears frequently in Base R scripts. Example: dataSurvey.

• lowercase: all letters are written continuously without separators. Especially for long names, this makes reading names quite hard. Example: datasurvey.

Different styles exist because R developed over many years with contributions from many programmers.

In this course:

• ✅ Use snake_case for your own objects and variables.
• 👀 Learn to recognize other styles when reading existing R code.

2.3 Add spaces around operators

Spaces make code easier to scan visually. Compare the following codes:

Bad example 🛑:

number<-5+3

Good example ✅:

number <- 5 + 3

2.4 Comment your code

Comments explain why you are doing something. Good comments help future-you understand past-you. Comments start with #:

# calculate mean age while excluding missing values
mean(age, na.rm = TRUE)

💡 Take-Aways

• Base R vs. tidyverse: Two common ways of writing R code. Base R works “out of the box” after installing R; the tidyverse is a set of additional packages with a consistent workflow especially for beginners
• Good coding style: Includes clear object names, consistent naming (e.g., snake style), adding spaces around operators, and adding comments to your code

🤓 Smart Hacks

Smart Hack 1: Using the styler package

Install the styler package by Kirill Müller and colleagues. If you then click on Addins at the top of your R Studio and select, for example, “Style active file”. The package automatically formats spacing, indentation, and layout according to tidyverse style conventions.

🎲 Quiz

round = (n, places) => {
  if (!places) return Math.round(n);
  const d = 10 ** places;
  return Math.round(n * d) / d;
}

function textReplacementWithText({ text, placeholder, correctText, fontFamily = "monospace", color = "#000000" }) {
  const parts = text.split(/\{\{input\}\}/); // Teilt den Text an den Eingabestellen

  const root = htl.html`<div style="font-size: HUGE; margin-top: -40; margin-bottom: -40; margin-left: -50px; line-height: 1.8; font-family: ${fontFamily}; color: ${color}; white-space: pre-wrap; text-indent: 0; display: flex; align-items: baseline;">
    <div style="flex: 1;">
      ${parts.map((part, index) =>
        htl.html`${part}${index < parts.length - 1 ? htl.html`<span style="display: inline-flex; align-items: baseline;">
          <input 
            type="text"
            placeholder="${placeholder}"
            style="padding: 3px; font-size: HUGE; border: 1px solid #ccc; margin-left: 0px; border-radius: 4px; width: calc(${correctText.length}ch + 1em); font-family: ${fontFamily}; color: ${color}; text-align: right; box-sizing: border-box; margin-right: 0.2em;"
            oninput=${(e) => {
              const feedbackElement = root.querySelector(`#feedback-final`);
              const allInputsCorrect = Array.from(root.querySelectorAll("input")).every((input) => input.value.trim() === correctText.trim());
              if (allInputsCorrect) {
                feedbackElement.textContent = "✅";
                feedbackElement.style.color = "green";
              } else {
                feedbackElement.textContent = "🔴";
                feedbackElement.style.color = "red";
              }
            }}
          /></span>` : ""}`
      )}
    </div>
    <span id="feedback-final" style="font-weight: bold; font-size: HUGE; margin-left: 0.5em; color: inherit;"></span>
  </div>`;

  return root;
}



function textReplacementTask({ placeholder, correctText, width = "300px", fontFamily = "monospace", color = "black" }) {
  let enteredText = ""; 

  const root = htl.html`<div style="font-size: 14px; line-height: 1.5; margin-bottom: 20px;">
    <h4>Bitte ersetzen Sie den Text:</h4>
    <!-- Eingabefeld -->
    <div style="display: flex; align-items: center;">
      <input
        type="text"
        placeholder="${placeholder}"
        style="padding: 5px; font-size: 14px; border: 1px solid #ccc; border-radius: 4px; width: ${width}; font-family: ${fontFamily}; color: ${color};"
        onInput=${(e) => {
          enteredText = e.target.value;
          root.value = enteredText;
          root.dispatchEvent(new CustomEvent("input"));
          updateFeedback();
        }}
      />
      <!-- Feedback -->
      <div id="feedback" style="font-weight: bold; font-size: 14px; margin-left: 10px; text-align: left; white-space: nowrap; color: inherit;"></div>
    </div>
  </div>`;

// Funktion zur Aktualisierung des Feedbacks
  function updateFeedback() {
    const feedbackElement = root.querySelector("#feedback");
    if (enteredText.trim() === correctText.trim()) {
      feedbackElement.textContent = "✅";
      feedbackElement.style.color = "green";
    } else if (enteredText.trim() === "") {
      feedbackElement.textContent = ""; 
    } else {
      feedbackElement.textContent = "🔴";
      feedbackElement.style.color = "red";
    }
  }

  root.value = null; 
  return root;
}


function singleChoiceInput({ options, correctIndex }) {
  let selectedAnswer = null;

  const root = htl.html`<div style="font-size: HUGE; line-height: 1.5; margin-bottom: 0px;">
    <!-- Antworten -->
    <div style="display: grid; row-gap: 12px;">
      ${options.map(
        (option, index) =>
          htl.html`<div style="display: flex; align-items: center;">
            <!-- Radiobutton und Option -->
            <label style="display: flex; align-items: center; padding-left: 4pt; font-weight: normal;">
              <input
                type="radio"
                name="singleChoice"
                value=${index}
                style="margin-right: 10px;"
                onChange=${() => {
                  selectedAnswer = index;
                  root.value = selectedAnswer;
                  root.dispatchEvent(new CustomEvent("input"));
                  updateFeedback();
                }}
              />
              <span>${option}</span>
            </label>
            <!-- Feedback -->
            <div id="feedback-${index}" style="font-weight: bold; font-size: 14px; margin-left: 10px; text-align: left; white-space: nowrap; color: inherit;"></div>
          </div>`
      )}
    </div>
  </div>`;

// Funktion zur Aktualisierung des Feedbacks
  function updateFeedback() {
    options.forEach((_, index) => {
      const feedbackElement = root.querySelector(`#feedback-${index}`);
      if (selectedAnswer === index) {
        feedbackElement.textContent =
          index === correctIndex ? "✅" : "🔴";
        feedbackElement.style.color = index === correctIndex ? "green" : "red";
      } else {
        feedbackElement.textContent = ""; // Löscht Feedback für nicht ausgewählte Optionen
      }
    });
  }

  root.value = null;
  return root;
}


function quizInput({ questions, options}) {
  let answers = questions.map(() => null);
  let root = htl.html`<div
      style="
        display: grid;
        grid-template-columns: 10% 10% 70% 10%;"
    >
      ${options.map(
        (opt) => htl.html`<div style="font-weight: bold; font-size: HUGE">${opt}</div>`
      )}
      <div style="font-weight: bold">Statement</div>
      <div style="font-weight: bold"></div>
      ${Array.from(questions.entries(), ([i, [question, correct]]) =>
        quizInputRow({
          question,
          options,
          correct,
          onChange: (newAnswer) => {
            answers[i] = newAnswer;
            root.value = answers;
            root.dispatchEvent(new CustomEvent("input"));
          }
        })
      )}
    </div>`;
  root.value = answers;
  return root;
}

function quizInputRow({
  question,
  options,
  correct,
  onChange = () => {}
}) {
  let root = htl.html`<div>`;

  function setAnswer(answer, initial = false) {
    morph(
      root,
      htl.html`<div style="display: contents"> 
      <form style="display: contents">
        ${options.map(
          (opt) =>
            htl.html`<label>&emsp;</label> 
            <input  
              name=${question} &emsp;
              type="radio"
              value="${opt}"
              checked=${opt === answer}
              onChange=${() => setAnswer(opt)}
            >
            </input>`
        )}
      </form>
      <div>${question}</div>
      <div> &emsp; ${
       answer === null ? "" : answer === correct ? "✅" : "🔴"
      }</div>
    </div>`
    );

    root.value = answer;
    if (!initial) {
      root.dispatchEvent(new CustomEvent("input"));
      onChange(answer);
    }
  }

  setAnswer(null, true);
  return root;
}

morph = require("https://bundle.run/nanomorph@5.4.2")

🎲 Question 1

Why does the following code produce an error? (Try running it)

days_week <- c("Monday", "Tuesday", "Wednesday", "Thursday", "Friday")
days_Week

🎲 Question 2

Which code is following good coding practice, independent of the exacty coding style?

MC_coding_styles_2 = [
    ["surveyData <- clean_data(survey_data)", "False"],
    ["avg_score <- mean(Score)", "False"],
    ["survey.data <- summarize(data.age)", "True"],
    ["name <- paste0(a,b,c)", "False"],
    ["mean_value<-mean(age)", "False"]
]

viewof answers_coding_styles_2 = quizInput({
  questions: MC_coding_styles_2,
  options: ["True", "False"]
})