Pratique du Shadowing: [Practice Problems] Regular Expressions (Regex) - Visually Explained - Apprendre l'anglais à l'oral avec la vidéo

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Have you tried our regular expressions practice exercises?
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If you have, great!
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We're going to work through the solutions now.
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If not, the problems are linked in the description.
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Alright, let's start with problem one.
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In this problem, we want to match all the phone numbers from the bulletin board text.
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Each phone number follows the format.
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A fixed area code, and a hyphen, followed by three digits, another hyphen, and a final four digits.
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Since every phone number starts with the same area code and hyphen, we write the literal characters 1, 2, 3, hyphen directly into the pattern box.
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Next, the middle group of numbers can have any combination of three digits.
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To match this, we use the character class 0 through 9 to match a single digit
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and follow it with the quantifier 3 to match exactly 3.
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Following the character class, we write another literal hyphen.
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To match the last four digits, like the middle three, we use a character class with 0 through 9.
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But to match four digits instead of 3, we use a quantifier of 4.
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Great!
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As we can see, this pattern matches both phone numbers and our bulletin board text.
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Fixed quantifiers like 3 and 4 are ideal when you know the exact length you're looking for.
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Phone numbers, zip codes, product codes, anything with a predictable structure.
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Quantifiers will also be quite useful in problem 2.
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In this problem, we want to write a regular expression to match all the prices in our text string.
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each price starts with a dollar sign followed by one
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or more digits a dot
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and exactly two digits for cents you might be tempted to start by writing the literal dollar sign character
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but in regex dollar sign is a special syntax
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that means end of line
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so it won't match the dollar sign character to match a
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literal dollar sign we put a backslash in front of it after the dollar sign comes the digits before the decimal,
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which we can match using a character class with 0 through 9.
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Since there could be any number of digits before the decimal, we use the plus quantifier to match one or more digits.
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Following this character class, we specify a dot.
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Remember, like the dollar sign, the dot is special syntax, called a wildcard, that matches any single character.
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To use a literal dot character, we need to write a backslash before it.
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Finally, cents always have exactly two digits.
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To match this, we write a character class allowing the digits 0 through 9 and a quantifier of 2.
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Awesome!
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With this pattern, all five prices are matched.
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Before we move on, we've now written the character class containing 0 through 9 several times.
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Since this is such a common pattern, regex syntax actually provides a shorthand for it.
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Instead of explicitly writing the character class, we write backslash d, which also means any digit.
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Awesome, our pattern is now more concise and we still get the same matches.
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We'll use the digit shorthand backslash d again in problem 3.
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In this problem, we want to match all the dates in the text.
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Each date has a month name, a day number, and a four-digit year.
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We'll start by matching the month names.
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Month names are made up of letters, both upper and lowercase, so we'll use a character class of all the uppercase and lowercase letters.
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To match one or more letters, we follow the class with the plus quantifier.
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After the month name comes a literal space.
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After the space, the day can be one digit or two.
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To match exactly one or two digits,
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we use the backslash d shorthand followed by a range quantifier with a lower bound of one and upper bound of two.
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Following the day, we write a literal comma and space.
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Lastly, the year is always four digits, so we write the digit shorthand and a quantifier of four.
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Awesome!
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With that pattern, we've matched all the dates.
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With these practice problems, you've seen how to write patterns for three different data types.
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If you want to go deeper on any of the concepts we used in this video, check out our regular expressions intro video linked in the description.
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We're working on lots more Python explainer videos like this one, so be sure to subscribe so that you don't miss out.
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If you have any questions or topics that you'd like to learn about, let us know in the comments below.
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We'd love to hear from you.
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Thanks for watching!

Context & Background

In this video, the speaker dives into the complex world of Regular Expressions (Regex), specifically targeting learners who aim to master this powerful tool for pattern matching. Through practical examples, the dialogue guides viewers through various problems, such as identifying phone numbers and prices, while explaining the essential components of Regex. This hands-on approach is ideal for English learners who wish to not only understand technical language but also enhance their English speaking skills. By engaging with these relatable scenarios, learners can practice regular expressions in a context that mirrors real-life applications, which is a fantastic way to improve English pronunciation and fluency.

Top 5 Phrases for Daily Communication

  • “Have you tried our regular expressions practice exercises?” - A great opening question to initiate discussions about learning methods or topics.
  • “Each phone number follows the format…” - Useful for explaining structured information, especially in professional contexts.
  • “To match this, we use…” - A phrase that can help clarify methods or processes in conversations.
  • “Awesome! With this pattern…” - An expression of excitement that can be used to motivate others or express approval.
  • “Instead of explicitly writing…” - This phrase helps learners understand alternatives in explaining methods or directions.

Step-by-step Shadowing Guide

To effectively tackle the complexities presented in this video, consider the following step-by-step shadowing approach:

  1. Watch Actively: Focus on the speaker's tone and pacing. Don’t just observe; listen for how they pronounce technical terms and common phrases.
  2. Pause & Repeat: After each key point, pause the video and attempt to shadow speak the phrases aloud. Mimicking the speaker will greatly help improve English pronunciation.
  3. Analyze the Content: Break down the syntax of Regex as discussed. Try to explain it in your own words, which will reinforce both your understanding of the topic and your ability to communicate it in English.
  4. Practice Regularly: Incorporate shadow speech exercises into your routine. Regular practice with daily phrases and technical dialogue will lead to greater fluency.
  5. Engage in Discussions: Find a study partner or forum where you can discuss what you've learned. Use the phrases from the video to ensure you are reinforcing your shadowing practice with real conversations.

By employing this shadowing guide, English learners can efficiently navigate through technical discussions, leading to a greater command of the language while mastering Regex. This method not only boosts comprehension but also empowers speakers to use language more effectively in everyday scenarios.

Qu'est-ce que la technique du Shadowing ?

Le Shadowing est une technique d'apprentissage des langues fondée sur la science, développée à l'origine pour la formation des interprètes professionnels. Le principe est simple mais puissant : vous écoutez de l'anglais natif et le répétez immédiatement à voix haute — comme une ombre suivant le locuteur avec un décalage de 1 à 2 secondes. Les recherches montrent une amélioration significative de la précision de la prononciation, de l'intonation, du rythme, des liaisons, de la compréhension orale et de la fluidité.