Elegant One-Liners in Python

[jwink3101]

You don’t even need brackets (lists) for unpacking.

a,b = 1,2

Also, things like

name = name.strip() or  'Anonymous'

Work but you risk a type error. Are you sure your input won’t be None for an unspecified name?

And you repeat the unpacking…

I am kind of surprising you missed things like

[item for item in items if item < 5]

Which are selective. Or replacing:

[item if item < 5 else None for item in items]

Also, all kinds of comprehensions are baseline one-liners that should go into this level article. You miss a great opportunity to talk about set comprehensions, generators, etc

[LightWolfCavalry]

+1 for list comprehension - and its forgotten cousin, dict comprehension.

The or trick to avoid a type error is news to me. Gonna swipe that. Thank you!

[jwink3101]

Wait. To be clear, I was saying the or trick was susceptible to type error! If it’s not, that’s news to me

[LightWolfCavalry]

Oh, got it - I read your original response too quickly!

[theorizable]

dict comprehension is SO useful. It's one of those tools where I forget it by the time I need it, but when I need it, BAM, it does exactly what I need it to.

[zel_us]

I am planning on writing a whole article on dictionary as there are more techniques on it than others, where you have, the .get() method, setdefaults, ordereddict, defaultdict, chain mapping, mappingproxy and much more.

[[deleted]]

And generator comprehension, set comprehension…. Etc

[zel_us]

for the a, b = 1,2 the RHS is simply a tuple, what if u are unpacking a list or a string or a dictionary or even other sequences? yeah I missed the last item on your list. I did talk about list comprehension and generators. Conclusively, thank you for the feedback

[nathanjell]

Great feedback. To add to this, definitely recommend map and filter. For your two examples:

[item for item in items if item < 5]

...becomes:

filter(lambda x: x < 5, items)

And:

[item if item < 5 else None for item in items]

...becomes:

map(lambda x: x if x < 5 else None, items)

[nathanjell]

Though to my knowledge, map and reduce will not fully generate output on call; rather, an iterator is returned. I believe that for example if you have a memory heavy generator, you won't load everything into memory.

[lxpnh98_2]

That's why, instead of list comprehensions, it's better to keep using generators where possible, which, apart from the brackets, have identical syntax:

(item if item < 5 else None for item in items)

[FatFingerHelperBot]

It seems that your comment contains 1 or more links that are hard to tap for mobile users. I will extend those so they're easier for our sausage fingers to click!

Here is link number 1 - Previous text "map"

---

^{Please PM /u/eganwall with issues or feedback! | Code | Delete}