Category: Python
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Want to understand Python’s comprehensions? Think in Excel or SQL.
Comprehensions are among the most useful constructs in Python. They merge the old, trusty “map” and “filter” functions into a single piece of compact, elegant syntax, allowing us to expression complex ideas in a minimum of code. Comprehensions are one of the most important tools in a Pythonista’s toolbox. And yet, I have found that…
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Why you should almost never use “is” in Python
It’s really tempting, when you first start to use Python, to use “is” rather than “==”. It’s a bit more readable, and it feels like it should just work, especially when you’re dealing with integers. In a language that uses “or” and “and” instead of “||” and “&&”, it seems logical to use “is” instead…
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Free Webinar on June 23rd: Introduction to Regular Expressions
If you’re a programmer, then you have likely heard about regular expressions (“regexps”) before. However, it’s also likely that you have tried to learn them, and have found them to be completely confusing. That’s not unusual; while regular expressions provide us with a powerful tool for analyzing text, their terse, dense, and cryptic syntax can…
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Free one-hour Webinar about Python’s magic methods on May 6th
I’ll be giving another free one-hour Webinar about Python — this time, about the magic methods that Python offers developers who want to change the ways in which their objects work. We’ll start off with some of the simplest magic methods, but will quickly move onto some of the more interesting and advanced ones —…
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Is it hashable? Fun and games with hashing in Python
One of the basic data types that Python developers learn to use, and to appreciate, is the dictionary, or “dict.” This is the Python term for what other languages call hashes, associative arrays, hashmaps, or hash tables. Dictionaries are pervasive in Python, both in the programs that we write, and in the implementation of the…
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Free Webinar in object-oriented Python on April 1st, 2015
Join me for an hour-long free Webinar about object-oriented Python on April 1st, 2015. I’ll discuss how to use and create classes in Python, how attributes form the core of Python’s object system, and how you should (and shouldn’t) think about Python’s objects. There will be plenty of time for Q&A. Come and join me;…
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A quick introduction to implementing Python iterators
When you put a piece of Python data into a “for” loop, the loop doesn’t execute on the data itself. Rather, it executes on the data’s “iterator.” An iterator is an object that knows how to behave inside a loop. Let’s take that apart. First, let’s assume that I say: for letter in ‘abc’: …
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If you don’t use “with”, when does Python close files? The answer is: It depends.
One of the first things that Python programmers learn is that you can easily read through the contents of an open file by iterating over it: f = open(‘/etc/passwd’) for line in f: print(line) Note that the above code is possible because our file object “f” is an iterator. In other words, f…
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All 50 exercises in “Practice Makes Python” are complete! (Plus, a sample exercise about taxes in Freedonia)
The latest draft of “Practice Makes Python,” my ebook intended to sharpen your Python programming skills, is now out. This draft includes all 50 exercises, solutions, and explanations that I had hoped to include in the book. I’m very excited to have reached this milestone, and appreciate the input from my many students and colleagues…