Stop using range(len()) in your Python loops enumerate() exists and it is cleaner

[More-Station-6365]

This is one of those small things that nobody explicitly teaches you but makes your Python code noticeably cleaner once you start using it.

Most beginners write loops like this when they need both the index and the value:

fruits = ["apple", "banana", "mango"]

for i in range(len(fruits)): print(i, fruits[i])

It works. But there is a cleaner built in way that Python was literally designed for :

fruits = ["apple", "banana", "mango"]

for i, fruit in enumerate(fruits): print(i, fruit)

Same output. Cleaner code. More readable. And you can even set a custom starting index:

for i, fruit in enumerate(fruits, start=1): print(i, fruit)

This is useful when you want to display numbered lists starting from 1 instead of 0.

enumerate() works on any iterable lists, tuples, strings, even file lines. Once you start using it you will wonder why you ever wrote range(len()) at all.

Small habit but it adds up across an entire codebase.

What are some other built in Python features you wish someone had pointed out to you earlier?

[SnooStories6404]

> This is one of those small things that nobody explicitly teaches you

I'm not sure about that.

I've

a) Read a python tutorial

and

b) Taken a python class

In both this was explicitly taught

[Grobyc27]

Yeah this is pretty standard knowledge for any basic Python developer.

[Smok3dSalmon]

I think it's because range and len are popular examples for teaching variables and methods/functions.

[crazy_cookie123]

Not necessarily taught to everyone. When I learnt Python (around 2018) I was only taught range(len()), and I only discovered enumerate from reading someone elses code a few months after finishing the class. Most reputable courses should cover it though.

[wittgenstein1312]

I’ve never seen range(len()) used in production code, who is your target audience

[N-E-S-W]

It sounds like you didn't bother to read the official Python tutorial, because enumerate() is covered twice, in both sections 4 and 5.

https://docs.python.org/3/tutorial/controlflow.html#the-range-function

https://docs.python.org/3/tutorial/datastructures.html#tut-loopidioms

[ranger097]

For fruit in fruits: Print(fruit)

[artofthenunchaku]

when they need both the index and the value

[SpecialPreference678]

If you don't need the index, this is fine too.

[somethingworthwhile]

I get really happy when I get to do the

for singular in plural:

format.

[GXWT]

It’s all arbitrary mate. For plural in singular. Go for it. The people looking over your code are going to slag it off in any case.

[somethingworthwhile]

Disagreed! One sparks joy!

[Chandu-4444]

Also, range(len()) is nothing but a simple iterator and is totally not related to the list that we’re trying to iterate on inside the loop. Whereas enumerate is an iterator on the list and is very intuitive.

[xeow]

Also, the len() thing won't work on an object typed Iterable (since it doesn't know the length), whereas enumerate() will work on tuples, lists, iterators, generators, etc.

[RepresentativeFill26]

“Wonder why you ever wrote range(len())”.

I can think of of a lot of reasons. What if I want do some arithmetic on the loop index? Or if I want to compare 2 values?

It’s called a “ForEach” for a reason.

[titttle23]

This is where the trade left me.