Category Archives for "Python"

My Black Friday sale is live! Take 50% off any course in Python or data science

As promised, the Black Friday sale has begun in my online store. Through Monday, my courses and books are all 50% off with the coupon code BF2019.

This includes all eight of the video courses:

It also includes all six cohorts of Weekly Python Exercise that will start in 2020!  Pay only $50 (rather than $100) per cohort with the coupon code BF2019:

People have had very kind things to say about my courses.  For example:

  • “The exercises are perfect for me because they are right in my “wheelhouse”. I have enough background knowledge that the context of the problems is relevant in my experience, yet I can’t just rattle off the solutions instantly. I have to puzzle over them as I try to solve them. I do usually achieve my goal of coming up with a solution that I am pleased with prior to the answer coming out on the following Monday.”  — Doug (about WPE)
  • “I was a total python noob when I started.  I just wanted to learn the syntax, how to look at problems and find the solution. You provided both.  Of course I did a lot of reading too but your teaching is instrumental in drilling some concepts into our brains.” — Jean-Pierre (about WPE)
  • “It was an amazing course. Apart from comprehensions, you have provided lots of information about Python programming. The exercises were really challenging.” — Jonayed (about “Comprehending Comprehensions”)
  • “I really liked the way you went slow and explained everything in microscopic detail, acknowledging where the NumPy syntax is non-intuitive.”  — David (about “NumPy”)

Again, you can take advantage of this discount?  Just use the coupon code BF2019 at checkout.

But be sure to do it in the coming days — because as of Tuesday, this year’s Black Friday sale will be completely over.

Black Friday: All of my Python courses are 50% off!

This coming Friday is “Black Friday,” when many stores offer big discounts on their products. I’m happy to say that from Friday through Monday, every course in my online store will be 50% off.

This includes all eight of the video courses in my online store:

There’s a new course in there — my brand-new “Intro Python: Functions” course tells you everything you need to understand writing and using Python functions. It’s aimed at people with programming experience but without a lot of experience with Python.

Oh, and you might also have noticed that my Pandas course is now complete, weighing in at 12.5 hours of videos (!), along with a large number of exercises.

But wait, there’s more: In 2020, I’ll be offering all six versions of Weekly Python Exercise (3 for beginners, and 3 for more experienced developers). If you buy them during this sale, you’ll save 50%. The cohorts might not be starting for several months, but you can lock in this price, and then begin the course along with the other students when it begins.

I’ll have more information about my Black Friday sale later this week. And I hope that this Black Friday will be an additional milestone as you improve your Python fluency.

Questions? Comments? Thoughts? Contact me at, or on Twitter as @reuvenmlerner .


Podcasts, podcasts, and even more podcasts

I’ve recently appeared on a whole bunch of podcasts about Python, freelancing, and even (believe it or not) learning Chinese! If you’re interested in any or all of these subjects, then you might want to catch my interviews:

  • Talk Python to Me: I spoke with Michael Kennedy (and Casey Kinsen) about freelancing in Python — and things to consider when you’re thinking of freelancing.
  • Programming Leadership: I spoke with Marcus Blankenship about why companies offer training to their employees, how they should look for training, and how best to take advantage of a course.
  • Profitable Python: I spoke with Ben McNeill about the world of Python training — how training works (for me, companies that invite me to train, and the people in my courses), how to build up an online business, and the difference between B2C vs. B2B. You can watch the video on YouTube, or listen to the audio version of the podcast!
  • Teaching Python: I spoke with Kelly Paredes and Sean Tibor about what it’s like to teach adults vs. children, and what tricks I use to help keep my students engaged. I learned quite a bit about how they teach Python to middle-school students!
  • You Can Learn Chinese: I’ve been studying Chinese for a few years, and spent some time chatting with Jared Turner about my experience, how I continue to improve, and how my Chinese studies have affected my work teaching Python. The entire episode is great, and my interview starts about halfway through.

In related news, you might know that I’ve been a co-panelist on the Freelancers Show podcast for the last few years. The entire panel (including me) recently left the show, and we’re currently discussing how/when/where we’ll restart.

I’ll be sure to post to my blog here when there are updates — but if you’re a freelancer of any level (new or experienced) who might be interested in sharing your stories with us, please contact me, so we can speak with you when we re-start in our new format.

Last chance to join Weekly Python Exercise in 2019!

Over the last year, I’ve taught in-person Python classes to companies in the US, Europe, Israel, India, and China. I’ve taught people from a variety of backgrounds, from absolute beginners to seasoned Pythonistas who want to improve their skills in new areas. And I’ve taught everything from intro Python to data science.

For all of the differences in background, jobs, courses, and education, I consistently got one request: Everyone wants to improve their skills, so that they can program in Python more fluently and easily — solving their current problems more easily, and taking on larger ones.

If this describes you — a competent and experienced Python developer who wants to know more, understand more, and do more with Python — then the new cohort of Weekly Python Exercise, starting tomorrow, is for you.

(Yes, it starts tomorrow. That means that tonight is the deadline to join. Really!)

Join the many developers from around the world who have improved their Python skills, one week at a time, with Weekly Python Exercise. Over the 15-week course, you’ll learn to work with iterators, generators, decorators, objects, and threads. You’ll improve your testing skills with “pytest”. You’ll communicate with other people in our cohort via our private forum. You’ll participate in my live office hours.

And best of all: Each week, you’ll get that much closer to Python fluency and mastery. This is great for your own personal satisfaction, of course, but will also help your career.

Also: The next advanced level cohort will start in March 2020.  So if you’re an experienced Python developer looking to improve your skills, this will be your last chance to do so for several months.  (A new basic-level cohort will be starting in January.)

If the price of WPE seems steep, maybe you qualify for one of my discounts — for pensioners/retirees, students, and anyone living outside of the world’s 30 richest countries. I want to help as many people as possible to improve their Python fluency, no matter where they live or where they are in life.

So join me tomorrow at Weekly Python Exercise, and start improving your Python tomorrow!


Quick Python tip: “int” strips strings of whitespace

Let’s say you’re writing a Python program that asks the user to enter a number, so that you can double it:

>>> n = input("Enter a number: ")
Enter a number:

Just doubling what we get is a bad idea, though. If the user enters “123”, then we’ll get this:

>>> print(n*2)

What’s going on? The “input” function always returns a string. The trailing newline character is removed, but we’re always going to get a string. If we multiply a Python string by 2, we get a new string back — a doubled version of what the user entered.

The obvious solution would be to use “int” to convert the string. For example, we could do this:

>>> print(int(n)*2)

But wait: What if the user enters extra whitespace on either side? That is, what if they do this:

>>> n = input("Enter a number: ")
Enter a number:         123        

You can see that there are extra space characters on either side of the ‘123’, and it becomes even clearer if we do this:

>>> print(f'"{n}"')
"       123       "
>>> print(len(n))

To avoid potential problems, you might want to use “str.strip”, a great method that (by default) removes all whitespace (i.e., space, tab, newline, carriage return, and vertical tab) from the edges of the string. In other words:

>>> print(int(n.strip())*2)

Sure enough, this will work, removing any whitespace characters from the ends of “n”. But guess what: It’s not necessary! That’s because Python’s “int” class automatically strips whitespace on any string it gets as input:

>>> int('5')
>>> int('   5    ')
>>> int('\n\n\t\t  5\t\t\v\v\t\t\n\r')

This is true, even though the str.isdigit/str.isnumeric/str.isdecimal methods will return “False” if you apply them to a string containing whitespace.

But be careful: If you apply “int” to the empty string, you’ll get a “TypeError” exception. And if you call “int” without any arguments, you’ll get the integer 0 back.

So save a few seconds when you convert strings to integers, and don’t bother stripping them first! You can rely on “int” to do it for you.

Want to improve your Python fluency? Join Weekly Python Exercise!

A new cohort of Weekly Python Exercise, my family of courses to improve your Python fluency, starts on November 5th.

This time, it’s an advanced-level cohort. We’ll explore topics such as iterators, generators, decorators, objects, and threads.

The course’s structure is simple:

  • Every Tuesday, you get a new question, along with “pytest” tests to check yourself
  • On the following Monday, you get the solution and explanation
  • In between, you can discuss your solutions (and problems) with others in your cohort, on our private forum
  • I also hold live video office hours, where you can ask me questions about the exercises

Questions or comments? Or perhaps you’re eligible for one of my discounts? Read more at, or send me e-mail at

But don’t delay, because November 5th is coming up soon. And why miss out on improving your Python knowledge and fluency?


Early-bird pricing for Weekly Python Exercise ends tomorrow

My native language is English: I grew up speaking it at home and school, and it’s my preference when reading, writing, and speaking. I studied in US schools through 12 grade, and then got both a bachelor’s degree and a PhD at American universities.  I’ve been writing for years, including 20 years as a columnist at Linux Journal.

Am I fluent in English? Yes, I’d say so.  And yet, I’m always reading tidbits about the history of English, how to speak more clearly, and how sharpen the language I use when writing.

Why? Because fluency isn’t a video game, in which you get a flashing sign saying, “Achievement unlocked: You’re fluent!”  No matter how fluent you currently are, there are ideas, techniques, and practices that you can still learn. You can always become better. 

How do you improve your fluency? The best way, of course, is practice. No matter how fluent you already are, more practice is always good.  As the old saying goes, the best way to become a good writer is to write. And the best way to become a better speaker is to speak.  And so forth.

What’s true for English, and other languages, is true for programming languages, as well.  If you want to be a better Python programmer, then you should be writing Python code, making mistakes, and learning from those mistakes.  Better yet, you should be discussing your mistakes (and techniques) with others, so that you can compare ideas and techniques, and learn from your peers.

This is the thinking that has driven my work with Weekly Python Exercise. Each of the six WPE courses is designed to help you become a more fluent programmer.

A new advanced-level cohort is starting on November 5th. But tomorrow (Tuesday, October 29th) is the last day you can sign up for the early-bird price of $80.

Here’s what some people have said about previous cohorts of WPE, when asked what they thought:

  • I was a total python noob when I started.  I just wanted to learn the syntax, how to look at problems and find the solution. You provided both… your teaching is instrumental in drilling some concepts into our brains.
  • I learned a lot of features of the language and had a fun time doing it. I also got to apply what I learned when programming for work.
  • I expected to see Python in real world examples. I am not disappointed, because during WPE there were many these examples with wide varieties of programming blueprints.
  • The exercises are perfect for me because they are right in my “wheelhouse”. I have enough background knowledge that the context of the problems is relevant in my experience, yet I can’t just rattle off the solutions instantly.

If you use Python on a regular basis, but still feel that you can learn more about advanced techniques: Iterators, generators, decorators, comprehensions, inner functions, threading, and useful PyPI packages, then Weekly Python Exercise is for you.

Early-bird pricing ends on Tuesday evening. After that, you can still sign up, but you’ll pay the full price (i.e., $100).  Why delay?

Click here to learn more about Weekly Python Exercise, and become a better Python developer.

Level up your coding skills with Weekly Python Exercise

Most days, I’m on-site at companies around the world, teaching various Python courses. And by far, the most common question that I get from students is: Once the course is over, how can I keep improving my Python skills?

The answer is simple: Practice. Just as you have to practice using a language in order to become fluent, you must keep using and practicing Python to become more proficient and efficient.

Weekly Python Exercise is a family of 15-week courses, each of which gives you a chance to improve your Python skills. On November 5th, I’ll be opening a new advanced-level cohort, aimed at people with at least 6 months of day-to-day Python experience.

During the course, you’ll improve your understanding of iterators, generators, decorators, threads, functional programming, and even a bunch of useful packages from PyPI.

Here’s how WPE works:

  • Every Tuesday, you receive a problem/question, along with “pytest” tests that your code should pass.
  • On the following Monday, you receive the solution code, along with explanatory text.
  • In between (as well as before and after), you can participate in our private forum, sharing code and solutions, and asking me questions.
  • Every month or two, I hold live office hours, at which you can ask me questions in real time.

Sounds simple? It is — and it should only take you about an hour every week. But by getting regular practice, your coding skills will improve, and your Python fluency will improve, too. You’ll be able to do more in less time, and will think more “Pythonically” than before.

Moreover: Join before October 29th, and you can take advantage of the early-bird pricing of $80. After that, you’ll still be able to join … but you’ll have to pay more.

Questions? Want to see some sample exercises? Or maybe you qualify for one of my many discounts? It’s all explained at . Or just send me e-mail at, and I’ll be delighted to answer.


Looking for Python podcast co-hosts

As you might know, I’m a panelist on the weekly “Freelancers Show” podcast, which talks about the business of freelancing.

The good news: The same company that’s behind the Freelancers Show,, is putting together a weekly podcast about Python, and I’m going to be on that, too! We’ll have a combination of discussion, interviews with interesting people in the Python community, and (friendly) debates over the current and future state of the language.

The better news: We’re looking for cohosts to participate in our panel discussion on a regular basis, say 2-4 times per month.

We’re looking for a diverse set of hosts, representing the breadth and width (and height, I guess) of the Python community — including skill levels, technical backgrounds, workplaces, and interests. You’ll also need a decent podcasting microphone. We’ll record weekly, on a day to be determined, at about 20:00 UTC for about 60-90 minutes.

If you’re talkative, articulate in English, interested in Python, able to commit to recording several times per month, and are willing to tolerate my jokes, then please be in touch, via e-mail ( or Twitter (@reuvenmlerner)! We’re hoping to start in the coming month or two.

I should note that this podcast is not meant to replace the existing, and amazing, podcasts that already exist in the Python community! I listen to them (and occasionally appear on them, too), and have a lot of respect for the hosts of (for example) Talk Python to Me, Python Bytes, Python Init, and Test & Code. I hope that what we create will be complementary to their shows, and grow the Python community to an even larger degree.

Sound interesting? Let me know!