Expression that returns mutated list Question: I’m looking for a single expression, mutates an element and returns the modified list The following is a bit verbose # key=0; value=3; rng=[1,2] [(v if i != key else value) for i, v in enumerate(rng)] Edit: I’m looking for a way to inline the following function in a …
Attemtping to solve twoSums leet code problem why doesn't the walrus operator with dict.get() work in python3 Question: Prompt: Given an array of integers nums and an integer target, return indices of the two numbers such that they add up to target. You may assume that each input would have exactly one solution, and you …
Walrus to unpack values within a list comprehension Question: I have a nested list holding dictionaries as mapping table using a tuple as key. I am struggling to zip the dictionary together so it can be exported by Pandas to csv file: l = [{(‘A’, ‘B’): 1}, {(‘A’, ‘C’): 2}, {(‘A’, ‘D’): 3}] def dynDictCombiner(item): …
Why is it that I "cannot use assignment expressions with comparison" in Python? Question: In the examples below x is assigned using the walrus operator and is then printed. mystring = "hello, world" #if 1 if x := mystring == "hello, world": print(x) #if 2 if x := (mystring == "hello, world"): print(x) #if 3 …
Python3.8 assignment expressions, use in list comprehension or as an expression Question: I recently discovered that assignment expressions exist. And I wanted to refactor some of my code to make use of them. Most of the places I wanted to use it were relatively straightforward to convert. However, I’m not sure of the syntax to …
With assignment expressions in Python 3.8, why do we need to use `as` in `with`? Question: Now that PEP 572 has been accepted, Python 3.8 is destined to have assignment expressions, so we can use an assignment expression in with, i.e. with (f := open(‘file.txt’)): for l in f: print(f) instead of with open(‘file.txt’) as …
Is it possible to add a where clause with list comprehension? Question: Consider the following list comprehension [ (x,f(x)) for x in iterable if f(x) ] This filters the iterable based a condition f and returns the pairs of x,f(x). The problem with this approach is f(x) is calculated twice. It would be great if …
