Meaning of list[-1] in Python - Stack Overflow
2018年9月19日 · All your return c.most_common()[-1] statement does is call c.most_common and return the last value in the resulting list, which would give you the least common item in that list. Essentially, this line is equivalent to:
What does [:-1] mean/do in python? - Stack Overflow
2013年3月20日 · Working on a python assignment and was curious as to what [:-1] means in the context of the following code: instructions = f.readline()[:-1] Have searched on here on S.O. and on Google but to no a...
What is :: (double colon) in Python when subscripting sequences?
In Python 3, your example range(N)[::step] produces a range object, not a list. To really see what is happening, you need to coerce the range to a list, np.array, etc. – PikalaxALT
How do I concatenate two lists in Python? - Stack Overflow
joined_list = [item for list_ in [list_one, list_two] for item in list_] It has all the advantages of the newest approach of using Additional Unpacking Generalizations - i.e. you can concatenate an arbitrary number of different iterables (for example, lists, tuples, ranges, and generators) that way - and it's not limited to Python 3.5 or later.
python - What does list[x::y] do? - Stack Overflow
2012年1月27日 · If you skip the end index, like in your question, it would take elements from the start index (x), pick every yth element until it reaches the end of the list if y is positive and beginning of the list if y is negative. E.g. l[1::-1] = [2,1] l[1::2] = [2,4,6] The default step size is 1.
python - What does [:] mean? - Stack Overflow
2019年7月16日 · @Macke: Note: As of Python 3.3, lists do provide clear and copy methods, equivalent to doing del mylist[:] or mylist[:] respectively. They're not required on mutable sequences in general, so if you might receive an arbitrary mutable sequence, you'd want to stick to slice based operations, but the named methods are at least available on list.
Best and/or fastest way to create lists in python
If you want to see the dependency with the length of the list n: Pure python. I tested for list length up to n=10000 and the behavior remains the same. So the integer multiplication method is the fastest with difference. Numpy. For lists with more than ~300 elements you should consider numpy. Benchmark code:
What does -> mean in Python function definitions? - Stack Overflow
2013年1月17日 · In more detail, Python 2.x has docstrings, which allow you to attach a metadata string to various types of object. This is amazingly handy, so Python 3 extends the feature by allowing you to attach metadata to functions describing their parameters and return values. There's no preconceived use case, but the PEP suggests several.
How to apply a logical operator to all elements in a python list
2009年11月24日 · def my_and(a_list): return not (False in a_list) def my_or(a_list): return True in a_list ANDing all elements will return True if all elements are True, hence no False in a list. ORing is similar, but it should return True if at least one True value is present in a list.
python - How do I get the last element of a list? - Stack Overflow
2009年5月30日 · The simplest way to display last element in python is >>> list[-1:] # returns indexed value [3] >>> list[-1] # returns value 3 there are many other method to achieve such a goal but these are short and sweet to use.