How are you supposed to break up a very long list comprehension?
[something_that_is_pretty_long for something_that_is_pretty_long in somethings_that_are_pretty_long]
I have also seen somewhere that people that dislike using ‘\’ to break up lines,
but never understood why. What is the reason behind this?
….
Think about a function that I’m calling for its side effects, not return values (like printing to screen, updating GUI, printing to a file, etc.).
def fun_with_side_effects(x):
…side effects…
return y
Now, is it Pythonic to use list comprehensions to call this func:
[fun_with_side_effects(x) for x in y if (…conditions…)]
Note tha….
Comprehensions show unusual interactions with scoping. Is this the expected behavior?
x = “original value”
squares = [x**2 for x in range(5)]
print(x) # Prints 4 in Python 2!
At the risk of whining, this is a brutal source of errors. As I write new code, I just occasionally find very weird errors due to rebinding — even now that I know it’s a p….
Is it possible to return 2 (or more) items for each item in a list comprehension?
What I want (example):
[f(x), g(x) for x in range(n)]
should return [f(0), g(0), f(1), g(1), …, f(n-1), g(n-1)]
So, something to replace this block of code:
result = list()
for x in range(n):
result.add(f(x))
result.add(g(x))
….
I want to compare 2 iterables and print the items which appear in both iterables.
>>> a = (‘q’, ‘r’)
>>> b = (‘q’)
# Iterate over a. If y not in b, print y.
# I want to see [‘r’] printed.
>>> print([ y if y not in b for y in a])
^
But it gives me a invalid syntax error where the ^ has been placed.
What is wrong abo….
Consider the following Python code with which I add in a new list2 all the items with indices from 1 to 3 of list1:
for ind, obj in enumerate(list1):
if 4 > ind > 0:
list2.append(obj)
How would you write this using list comprehension, if I have no access to the indices through enumerate?
something like:
list2 = [x for x in list1 if 4 ….
This question already has answers here:
What does “list comprehension” and similar mean? How does it work and how can I use it?
(5 answers)
Closed 4 months ago.
Wrote this function in python that transposes a matrix:
def tra….
I would like to know if there is a better way to print all objects in a Python list than this :
myList = [Person(“Foo”), Person(“Bar”)]
print(“\n”.join(map(str, myList)))
Foo
Bar
I read this way is not really good :
myList = [Person(“Foo”), Person(“Bar”)]
for p in myList:
print(p)
Isn’t there something like :
print(p) for p in myList
If not….
Lets suppose I have a list like this:
mylist = [“a”,”b”,”c”,”d”]
To get the values printed along with their index I can use Python’s enumerate function like this
>>> for i,j in enumerate(mylist):
… print i,j
…
0 a
1 b
2 c
3 d
>>>
Now, when I try to use it inside a list comprehension it gives me this error
>>> [i,j for i,j in enumerate(my….
Suppose I have a list like:
mylis = [‘this is test’, ‘another test’]
How do I apply a function to each element in the list? For example, I want to be able to apply str.upper to get
[‘THIS IS TEST’, ‘ANOTHER TEST’]
….