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Reuven M. Lerner

@lernerpython.com

3.3K followers 590 following 420 posts

Helping you become more confident with Python and Pandas since 1995. • Courses: LernerPython.com • Newsletters: BetterDevelopersWeekly.com • BambooWeekly.com • Books: PythonWorkout.com • PandasWorkout.com • Videos: YouTube.com/reuvenlerner

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Reuven M. Lerner @lernerpython.com · Nov 12

Hi there! 👋 I'm Reuven, and I've been teaching #Python and Pandas around the world since 1995.

Just about every day, my students ask great questions. I love sharing those questions (and my answers), along with other resources to help you improve your Python/Pandas fluency.

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Reuven M. Lerner @lernerpython.com · 12h

The US has imposed big tariffs on Chinese goods. Have they affected China's exports to the US? To the rest of the world?

Bamboo Weekly asks you to answer these questions using #Python and #pandas , using Chinese export stats.

Get new data challenges every Wednesday: bambooweekly.com .

Reuven M. Lerner @lernerpython.com · 5d

The US government is shut down! But Bamboo Weekly is still is on the job, with #dataanalysis puzzles — this time, about US federal employees.

Get new #Python #Pandas challenges on Wednesdays, with detailed solutions and explanations on Thursdays, at bambooweekly.com .

Reuven M. Lerner @lernerpython.com · 13d

The UN is in session. For politicians, that means speeches and fancy meetings.

And so, Bamboo Weekly's latest batch of #Pandas challenges use grouping, text analysis, and pivot tables to review Security Council records.

Check them out: bambooweekly.com

Reuven M. Lerner @lernerpython.com · 19d

I had a great time at PyCon India, and in Bangalore. But the traffic was ... quite the experience, both taking taxis crossing streets.

For this week's data-analysis problems in Bamboo Weekly, I thus looked at vehicle registrations in India.

Check it out at bambooweekly.com!

Reposted by Reuven M. Lerner

PyCharm, a JetBrains IDE @pycharm.dev · 23d

📊 Who is using Python, and how?

@lernerpython.com explores the latest Python Developer Survey in the latest installment of “Bamboo Weekly”, a newsletter featuring new Pandas data analysis puzzles and solutions every week.

➡️ Explore Reuven’s deep-dive: jb.gg/bwnjbs

jb.gg

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Reuven M. Lerner @lernerpython.com · 23d

You know what would be even cheaper? No reporting requirements whatsoever.

The point of regular reports isn't to save (or spend) money. It's to provide investors with transparency, reducing fraud and improving the overall market.

It's no surprise that a grifter like Trump hates such reports.

Reuven M. Lerner @lernerpython.com · 27d

Ever wonder which airlines are more cramped? Or how much more room premium economy or business class gives you?

In the latest Bamboo Weekly, we use #Pandas to analyze airline seating data with grouping, pivot tables, and regular expressions.

New Pandas questions every Wednesday: bambooweekly.com

Reuven M. Lerner @lernerpython.com · 28d

It's hot and rainy in Taipei. But just how rainy?

In my PyCon TW lightning talk, I downloaded, analyzed, and plotted rain data using Pandas.

I did it all in @marimo.io , and posted it to the "Molab" server, so you run the analysis in your browser: molab.marimo.io/notebooks/nb...

Reuven M. Lerner @lernerpython.com · Aug 28

The latest Bamboo Weekly examines wind turbines:

• Which countries generate the most electricity from wind?
* Do countries that invest in wind power also invest in solar?

Level up your #Python/#Pandas skills! New questions every Wednesday, new solutions every Thursday.

bambooweekly.com

Reuven M. Lerner @lernerpython.com · Aug 28

Using uv for your #Python projects? You're probably doing it wrong.

While uv *can* replace pip, pyenv, and venvs, you really should be using it differently. If you do, things get easier and more straightforward.

Read more: lerner.co.il/2025/08/28/y...

You're probably using uv wrong

[This is adopted from my "Better developers" newsletter: https://BetterDevelopersWeekly.com ] Like many others in the Python world, I've adopted "uv", the do-everything, lightning-fast package manager...

lerner.co.il

Reuven M. Lerner @lernerpython.com · Aug 14

Have Canadians stopped visiting the US?

In this week's Bamboo Weekly, we examined numbers from the Canadian government. And yes, we saw a steep year-over-year drop in the first six months of 2025.

Level up your #Python/#Pandas skills every Wednesday, at bambooweekly.com .

Reuven M. Lerner @lernerpython.com · Aug 14

Are fewer Canadians visiting the US now that Trump is president?

In the latest Bamboo Weekly, we examine Canadian border-crossing statistics — while reducing our memory footprint, using time series, and creating pivot tables.

Improve your #Python #Pandas skills every Wednesday: bambooweekly.com

Reuven M. Lerner @lernerpython.com · Aug 13

Using #Python #Pandas? Then you're probably using "groupby".

I see people making the same mistakes with "groupby" all of the time. In my latest video, I describe these mistakes, tell you what the problem is, and explain how to fix it.

Check it out: youtu.be/jJNXRLjeYwE?...

Five Pandas "groupby" mistakes to avoid

YouTube video by Python and Pandas with Reuven Lerner

youtu.be

Reuven M. Lerner @lernerpython.com · Aug 6

Last week's US jobs report reduced previous estimates, leading to the firing of the head statistician.

Today's Bamboo Weekly examines the BLS data, calculating these changes ourselves with #Python #Pandas.

Improve your data skills every Wednesday: bambooweekly.com

Reuven M. Lerner @lernerpython.com · Aug 5

Do you usually separate groups of digits with commas? Do that in #Python, and you'll have trouble.

In my latest video, I show you how to separate digits in Python, and then how to display numbers separated by commas, too.

Check it out: youtu.be/hhgg9SFyQZs?...

Commas in Python integer input and output

YouTube video by Python and Pandas with Reuven Lerner

youtu.be

Reposted by Reuven M. Lerner

Norman Eliaser (he/him) @eliasern.bsky.social · Aug 3

IIBA Chicagoland Chapter
Showcasing the Powers of Jupyter -
@lernerpython.com Reuven Lerner
Join us on Zoom this Wed!
Aug 6, 6:00-7:30pm CT
Cost: Free

chicago.iiba.org/.../showcasi...

#Python #Jupyter #Pandas #DataFormats #Export #Import #BusinessAnalysis

Home Page | Chicagoland

chicago.iiba.org

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Reuven M. Lerner @lernerpython.com · Jul 30

Tom Lehrer passed away this week, so the latest Bamboo Weekly is about analyzing his lyrics with #Python #Pandas:

• Create a data frame from text files
• Using .str methods
• Extract text with regex

Improve your data-analysis skills each Wednesday: bambooweekly.com

Bamboo Weekly

Level up your data-analysis skills with Python and Pandas, solving problems with real-world data sets based on current events.

BambooWeekly.com

Reuven M. Lerner @lernerpython.com · Jul 30

Oh, and I had *completely* forgotten that we met when you took my class with Cisco! I figured that we had met at PyCon US a number of years ago...

Reuven M. Lerner @lernerpython.com · Jul 30

Yeah, I wouldn't phrase it this way. I think you're somewhat confusing the idea of a constant (where a variable's reference to a value is fixed and unchangeable) and immutable (where a value cannot change).

Maybe this will help: www.youtube.com/watch?v=XPrZ...

Python immutable vs. constants — how are they different?

YouTube video by Python and Pandas with Reuven Lerner

www.youtube.com

Reuven M. Lerner @lernerpython.com · Jul 30

True -- we talk about mutable vs. immutable as if they were strictly defined categories, and that everything falls into one or the other. But aside from some builtin data structures, nothing in Python is truly immutable. We can create almost-immutable values, but it's never 100%.

Reuven M. Lerner @lernerpython.com · Jul 29

Fair enough!

That said, I always love showing this to people:

t = ([10, 20, 30], [40, 50, 60])
t += [35]

which has more to do with magic methods than with immutability, but I'll do anything to shock my students. :-)

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Reuven M. Lerner @lernerpython.com · Jul 29

No! You can think of the tuple as containing a fixed number of reference (pointers, more or less) to another object. The references cannot change -- you can't add new ones, remove existing ones, or modify existing ones -- but the objects to which they refer *can* change.

Reuven M. Lerner @lernerpython.com · Jul 29

#Python people talk a lot about "mutable" and "immutable" data.

What does that mean, though?

In my latest video, I break it down, showing you what it means for a data structure (e.g., a list or dict) to be mutable.

youtu.be/qfQBMq4IH1s?...

What does "mutable" mean in Python?

YouTube video by Python and Pandas with Reuven Lerner

youtu.be

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Reuven M. Lerner @lernerpython.com · Jul 28

Ever use the x=y=z syntax in #Python, assigning multiple variables at the same time?

Ever discover it didn't quite work right?

In my latest video, I show you what's happening behind the scenes, and where this syntax can bite you: youtu.be/rm_T1x3VnMU?...

When Python variable assignment goes wrong -- issues with x=y=z

YouTube video by Python and Pandas with Reuven Lerner

youtu.be

Reuven M. Lerner @lernerpython.com · Jul 27

I'm now an old hand at #Python conferences, and feel very comfortable there. But for many, it can be overwhelming and daunting.

Here are some tips for anyone attending a conference for the first time, who wants to get the most out of it: lerner.co.il/2025/07/27/h...

How to conference

I love conferences. I enjoy everything about them -- the nonstop stream of learning, the chance to see old friends and meet new ones, and just generally to be around a lot of interesting, smart,

lerner.co.il

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