How can I simplify this for a PyCharm tutorial code?

Question

I was doing some tutorials online and I being working with PyCharm, (an excellent IDE btw) but, it shows me that i could simplify a if statement

This is only for my knowledge, nothing more

if len(tasks) == []:

The suggestion says: Expression can be simplified. This inspection detects equality comparison with a boolean literal.

your statement can be simplified to `if False` because `len` returns `int` and `[]` is an empty `list` — Azat Ibrakov, Jul 16 '19 at 07:04

hiro protagonist · Answer 1 · 2019-07-16T10:06:07.197

3

len(tasks) == [] will always be False; you probably mean len(tasks) == 0. which is usually just used as

if not tasks:
    do_stuff()

the doc on truth value testing may be helpful.

edited Jul 16 '19 at 10:06

answered Jul 16 '19 at 06:22

hiro protagonist

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You are right that it is usually used as `if tasks:` but checking `if len(tasks) == 0:` is recommended for code clarity. – Adirio Jul 16 '19 at 06:36
2

PEP8 guide recommends using the falsy-ness of an empty list i.e. `if tasks:`. _For sequences, (strings, lists, tuples), use the fact that empty sequences are false._ https://www.python.org/dev/peps/pep-0008/#id51 – abdusco Jul 16 '19 at 06:52
@Adirio i disagre... to me `if tasks` looks more *pythonic* (not that this is a well defined term...). where does your recommendation come from? would you have a reference? – hiro protagonist Jul 16 '19 at 09:34
`if tasks:` is more pythonic and is recommended by the PEP8, as @abdusco said (https://www.python.org/dev/peps/pep-0008/#programming-recommendations, third starting from the bottom). What I meant is that writting `if len(tasks) == 0` is what I recommend to begginers as it is more clear. If you ask about my opinion, that recomendation of PEP8 goes against The Zen Of Python (explicit is better than implicit) (https://www.python.org/dev/peps/pep-0020/) – Adirio Jul 16 '19 at 09:47

abdusco · Answer 2 · 2019-07-16T06:54:21.783

1

You can just do

if tasks:
    # do something

which will evaluate to false if tasks list is empty [] or is None.

From PEP8 guide

For sequences, (strings, lists, tuples), use the fact that empty sequences are false.

https://www.python.org/dev/peps/pep-0008/#id51

edited Jul 16 '19 at 06:54

answered Jul 16 '19 at 06:22

abdusco

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score 0 · Answer 3 · answered Jul 16 '19 at 07:02

len() is the Built-in Functions in Python. This is what documentation explain about len() functions.

Return the length (the number of items) of an object. The argument may be a sequence (such as a string, bytes, tuple, list, or range) or a collection (such as a dictionary, set, or frozen set).

So len() function always return an integer value.

>>> _list = []
>>> len(_list)
0  # It's 0, because it's an empty list.
>>> len(_list) == []
False  # Yes, because 0 is not equal to list
>>> 0 == []
False  # Same as before, len(_list) always return 0

I think You are check the list is empty or not, can do it easily in this way.

if tasks:  # or len(tasks) != 0
    # do something when list has one or more values:
else:
    # do something when list is empty

You can refer more about from How do I check if a list is empty? question.

score 0 · Answer 4 · answered Jul 16 '19 at 08:38

0

if not tasks:
   do_stuff()

You can directly apply not operator on array to check if the array is empty or not.

answered Jul 16 '19 at 08:38

Asnim P Ansari

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How can I simplify this for a PyCharm tutorial code?

4 Answers4