Meaning of list[-1] in Python - Stack Overflow I have a piece of code here that is supposed to return the least common element in a list of elements, ordered by commonality: def getSingle(arr): from collections import Counter c = Counte
Python: list of lists - Stack Overflow The first, [:], is creating a slice (normally often used for getting just part of a list), which happens to contain the entire list, and thus is effectively a copy of the list The second, list(), is using the actual list type constructor to create a new list which has contents equal to the first list
slice - How slicing in Python works - Stack Overflow The 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 is the difference between List. of and Arrays. asList? @Sandy Chapman: List of does return some ImmutableList type, its actual name is just a non-public implementation detail If it was public and someone cast it to List again, where was the difference? Where is the difference to Arrays asList, which returns a non-public List implementation, that throws an exception when attempting add or remove, or the list returned by Collections
How to cast List lt;Object gt; to List lt;MyClass gt; - Stack Overflow (List<Customer>)(Object)list; you must be sure that at runtime the list contains nothing but Customer objects Critics say that such casting indicates something wrong with your code; you should be able to tweak your type declarations to avoid it But Java generics is too complicated, and it is not perfect Sometimes you just don't know if there is a pretty solution to satisfy the compiler
How can I pass a list as a command-line argument with argparse? Don't use quotes on the command line 1 Don't use type=list, as it will return a list of lists This happens because under the hood argparse uses the value of type to coerce each individual given argument you your chosen type, not the aggregate of all arguments You can use type=int (or whatever) to get a list of ints (or whatever)
How do I make a flat list out of a list of lists? - Stack Overflow If your list of lists comes from a nested list comprehension, the problem can be solved more simply directly by fixing the comprehension; please see How can I get a flat result from a list comprehension instead of a nested list? The most popular solutions here generally only flatten one "level" of the nested list See Flatten an irregular (arbitrarily nested) list of lists for solutions that
How to overcome TypeError: unhashable type: list A work around is create a custom_list type that inherits list with a method __hash__() then convert your list to use the custom_list datatype still better to use built-in types
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