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Bookmark or Share- python - if/else in a list comprehension - Stack OverflowSince a list comprehension creates a list, it shouldn't be used if creating a list is not the goal; it shouldn't be used simply to write a one-line for-loop; so refrain from writing [print(x) for x in range(5)] for example.
- slice - How slicing in Python works - Stack OverflowThe first way works for a list or a string; the second way only works for a list, because slice assignment isn't allowed for strings. Other than that I think the only difference is speed: it looks like it's a little faster the first way. Try it yourself with timeit.timeit() or preferably timeit.repeat().
- What are the options to clone or copy a list in Python? - Stack Overflow@loved.by.Jesus: Yeah, they added optimizations for Python level method calls in 3.7 that were extended to C extension method calls in 3.8 by PEP 590 that remove the overhead of creating a bound method each time you call a method, so the cost to call alist.copy() is now a dict lookup on the list type, then a relatively cheap no-arg function call that ultimately invokes the same thing as slicing.
- Identify duplicate values in a list in Python - Stack Overflowlist.count() is a O(N) job (all elements in the list are compared to count) and you are doing this in a loop over N elements, giving you quadratic performance, O(N^2). So for a 10-element list 100 steps are executed, for a 1000 element list 1 million, etc. –
- How to list all installed packages and their versions in Python?For Windows 10, I think this is what you are looking for a list of available installed Pythons. This is different from a list of packages as you can see below. Also, on Ubuntu 20.04, I think the command is Python3 -0 list. Yes, this works similar to node version manager. c:\Users\user\AppData\Local\Programs\Python>py -0 list Python 0 not found!
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