if not a:
print("List is empty")
Using the implicit booleanness of the empty list is quite Pythonic.
Top answer 1 of 16
7312
if not a:
print("List is empty")
Using the implicit booleanness of the empty list is quite Pythonic.
2 of 16
1556
The Pythonic way to do it is from the PEP 8 style guide.
For sequences, (strings, lists, tuples), use the fact that empty sequences are false:
# Correct: if not seq: if seq: # Wrong: if len(seq): if not len(seq):
GeeksforGeeks
geeksforgeeks.org › python › python-check-if-list-empty-not
Check if a list is empty or not in Python - GeeksforGeeks
October 24, 2024 - The simplest way to check if a list is empty is by using Python's not operator. The not operator is the simplest way to see if a list is empty. It returns True if the list is empty and False if it has any items.
How do I check if this list is "empty"?
Well there are a few ways you could deal with this. First would be to check if userInput is an empty string before converting it to a list. Another possibility would be to filter the list to remove all empty strings, eg via a list comprehension. Or you could do the filtering inside the loop you already have that converts to integers. Or, again inside that loop, you could use a counter variable to keep track of how many integers you've converted, and print an error afterwards if it's 0. And so on. The main thing here is that you should get away from thinking about how to code something, but first work out what the steps should be, and only then code it. More on reddit.com
7
1
December 8, 2022why is an empty list True?
You're not asking if the list itself is true here, you're asking if every member of the list is true. And they are: every single one of those 0 items is true - not a single one was false! More generally, this comes down to what is called a " vacuous truth " regarding universal statements. Ie. is the statement: "All unicorns in my house are white" true? In formal logic, the answer to this is "True". "All X are Y" is considered to be equivalent to "There is no X that is non-Y". There are no unicorns in my house that are not white (because there are no unicorns in my house), so this is obviously true, which likewise gives us the answer to the equivalent "All the unicorns in my house are white" statement (And likewise "All unicorns in my house are purple" is also true). In English, this might seem a bit confusing, because we're often not making statements about empty sets - conversationally, the fact that we talk about something tends to hint at or imply that it exists. But in logic, it's often necessary to talk about empty (or potentially empty) sets, and this is a consistent way to treat them. More on reddit.com
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November 4, 2022Check to see if empty with If not ___
Read https://docs.python.org/3/library/stdtypes.html#truth More on reddit.com
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3
June 30, 2022Why is it common in python to make an empty list or dict first?
In your case it’s completely useless however many times we run a loop and append to a list or add to a variable counter or many such things. This has to exist before we do so. I mean I thought a lot of list comprehension was supposed to help mitigate this very thing lol. for element in some_list: my_list.append(element*2) Will fail. More on reddit.com
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September 19, 2023Videos
Checking for an empty list in Python
05:43
Python Program #54 - Check If a List is Empty in Python - YouTube
01:10
How to check Python List is Empty | Ways to check Python List is ...
06:42
How To Check If A List Is Empty In Python - YouTube
- YouTube
01:30
How to check if list is empty in Python - YouTube
Python Morsels
pythonmorsels.com › checking-for-an-empty-list-in-python
Checking for an empty list in Python - Python Morsels
August 20, 2024 - One way to check whether a list is empty is to check the length of that list. If the length is 0, the list must be empty: >>> numbers = [] >>> if len(numbers) == 0: ... print("The list is empty.") ... The list is empty.
Curict
en.curict.com › item › 9a › 9a5983d.html
Checking if a Python list is empty
Since None is also considered False, if you want to strictly compare None and an empty list, you can use the “is None” operator to check. ... # Checking for an empty list considering None if emptyList is None: print('It is None') elif not emptyList: print('The list is empty')
Medium
medium.com › swlh › efficiently-checking-for-an-empty-list-in-python-76b76099fbd3
Efficiently Checking for an Empty List in Python | by Frank Scholl | The Startup | Medium
November 22, 2019 - The way lists are compared to see if they are equal in python is by iterating through both lists and verifying that each element is equal. The result is placed on the top of the stack. POP_JUMP_IF_FALSE takes the first element off the top of the stack and jumps to the indicated byte number if the value is false. Of the three methods, this is the most complex way to check for a list being empty.
Python documentation
docs.python.org › 3 › library › stdtypes.html
Built-in Types — Python 3.14.3 documentation
6 days ago - While the in and not in operations are used only for simple containment testing in the general case, some specialised sequences (such as str, bytes and bytearray) also use them for subsequence testing: ... Values of n less than 0 are treated as 0 (which yields an empty sequence of the same type as s). Note that items in the sequence s are not copied; they are referenced multiple times. This often haunts new Python programmers; consider: >>> lists = [[]] * 3 >>> lists [[], [], []] >>> lists[0].append(3) >>> lists [[3], [3], [3]]
freeCodeCamp
freecodecamp.org › news › how-to-check-if-a-list-is-empty-in-python
Python isEmpty() equivalent – How to Check if a List is Empty in Python
April 19, 2023 - In the example above, we compared the people_list list to an empty list: if people_list == []
Built In
builtin.com › articles › python-check-if-list-is-empty
Python Check if a List Is Empty: A Guide | Built In
November 7, 2024 - There are a variety of methods that can be used to check if a list is empty in Python, including the Truth Value Testing method, the len() function and the == operator. Learn more.
Better Stack
betterstack.com › community › questions › how-to-check-if-list-is-empty-in-python
How do I check if a list is empty in Python? | Better Stack Community
January 26, 2023 - You can check if a list is empty by using the len() function to check the length of the list.
Reddit
reddit.com › r/learnpython › how do i check if this list is "empty"?
r/learnpython on Reddit: How do I check if this list is "empty"?
December 8, 2022 -
I'm completely stumped on a computer science assignment because our lecturer has given us zero information. We're supposed to have the user input a list and check if the list is in decreasing order and print a suitable message if it is. That part works fine. However, if the list is "empty" (I'll explain the quotations in a second) then it should print the list is empty.
The problem is that, according to our brief we're supposed to use .split(",") in order to allow the user to separate their numbers with commas. The problem lies in the fact that even if a user hits enter without inputting anything, the list is still '1' long with just an empty string. I've been scouring the web to find out how to check if a list is empty. But all the tutorials have so far just been in relation to actually empty lists (as in, list = []). One did use the all() function to check that all items in the list were strings, which did work and let me print that the list is empty, but broke the original function. Could someone please help me I'm tearing my hair out with this.
--
def checkOrder():
# checks, etc.
integer_list = []
listLength = len(integer_list)
increasing = 0
decreasing = 0
singleValue = 0
# Converting inputted numbers into a split list
userInput = input("Please enter your numbers seperated by a comma (,):")
inputtedStrings = userInput.split(",")
for number in inputtedStrings:
inputtedIntegers = int(number)
integer_list.append(inputtedIntegers)
# Enumerating list
for i, val in enumerate(integer_list[:-1]):
if val <= integer_list[i+1]:
increasing = 1
elif val >= integer_list[i+1]:
decreasing = 1
# Check for a single value
if len(integer_list) == 1:
singleValue = 1
if len(integer_list) == 1 and
print("The list is empty.")
if increasing == 1:
print("The numbers are in increasing order.")
elif decreasing == 1 or singleValue == 1:
print("The numbers are in decreasing order.")
checkOrder()
--
Top answer 1 of 5
8
Well there are a few ways you could deal with this. First would be to check if userInput is an empty string before converting it to a list. Another possibility would be to filter the list to remove all empty strings, eg via a list comprehension. Or you could do the filtering inside the loop you already have that converts to integers. Or, again inside that loop, you could use a counter variable to keep track of how many integers you've converted, and print an error afterwards if it's 0. And so on. The main thing here is that you should get away from thinking about how to code something, but first work out what the steps should be, and only then code it.
2 of 5
3
arr = [''] print(any(arr)) # False any and all are pretty useful built-in functions for iterative boolean checks.
Vultr
docs.vultr.com › python › examples › check-if-a-list-is-empty
Python Program to Check If a List is Empty | Vultr Docs
December 6, 2024 - Using direct boolean evaluation is typically the simplest and most performant. However, explicitly comparing against an empty list or using the len() function might clarify intent in contexts where code readability is paramount.
TutorialsPoint
tutorialspoint.com › how-to-check-if-a-list-is-empty-in-python
How to check if a list is empty in Python?
April 23, 2025 - Here we will use the len() function to check whether the list is empty or not. So, first create a variable to store the input empty list. Check whether the length of the list is equal to 0 using the len() function in an if conditional statement. Print an Empty list if the length of the list ...
Flexiple
flexiple.com › python › check-if-list-is-empty-python
Python isEmpty() equivalent – How to Check if a List is Empty in Python - Flexiple - Flexiple
March 14, 2022 - Check if a list is empty in Python by using the len() function or compare the list directly to an empty list. For example, if len(my_list) 0: or if my_list []: are common methods.
Medium
pavolkutaj.medium.com › how-to-check-if-a-list-dict-or-set-is-empty-in-python-as-per-pep8-35d8c64d07d0
How to Check if a List, Dict or Set is Empty in Python as per PEP8 | by Pavol Z. Kutaj | Medium
September 7, 2023 - in effect, it is saying that __nonzero__ is the interface for testing emptiness (__bool__ in python 3 → built-in bool())
AskPython
askpython.com › home › check if a list is empty – 3 easy methods
Check if a List is Empty - 3 Easy Methods - AskPython
July 17, 2020 - Python len() function can be used to check if a list is empty.
Squash
squash.io › how-to-check-if-list-is-empty-in-python
How To Check If List Is Empty In Python
December 21, 2023 - In this example, we define an empty list my_list and then use the len() function to check its length. If the length is equal to zero, we print "The list is empty". Otherwise, we print "The list is not empty".
Spark By {Examples}
sparkbyexamples.com › home › python › check if the list is empty in python
Check if the List is Empty in Python - Spark By {Examples}
May 31, 2024 - We can also use the len() function to check if a list is empty, passing a sequence object as an argument to this function returns the number of elements in the object, for an empty list, it returns 0 which is False in Python.
Codedamn
codedamn.com › news › python
Python List Is Empty: All Methods to Check
July 1, 2023 - A: No, Python does not have a built-in function specifically to check if a list is empty. However, you can use Python's built-in len() function or simply use the list in a boolean context to check if it's empty. Q: Which method is best for checking ...
Sentry
sentry.io › sentry answers › python › check if a list is empty in python
Check if a list is empty in Python | Sentry
March 15, 2023 - The Problem How do I check if a list is empty in Python? The Solution The Python style guide, PEP-8, recommends checking whether a list (or other sequence) is…
iO Flood
ioflood.com › blog › python-check-if-list-is-empty
Learn Python: How To Check If a List Is Empty?
June 27, 2024 - Throughout this guide, we’ve explored various methods to check if a list is empty in Python. We started with the simple yet powerful not operator, which returns True when a list is empty and False otherwise.