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:
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!
List of zeros in python - Stack Overflow
2011年12月16日 · See why [] is faster than list() There is a gotcha though, both itertools.repeat and [0] * n will create lists whose elements refer to same id. This is not a problem with immutable objects like integers or strings but if you try to create list of mutable objects like a list of lists ([[]] * n) then all the elements will refer to the same object.
Best way to remove elements from a list - Stack Overflow
2014年2月2日 · This makes indexing a list a[i] an operation whose cost is independent of the size of the list or the value of the index. When items are appended or inserted, the array of references is resized. Some algorithm is applied to improve the performance of appending items repeatedly; when the array must be grown, some extra space is allocated so the ...
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?
2017年10月5日 · Let summarize the differences between List.of and Arrays.asList. List.of can be best used when data set is less and unchanged, while Arrays.asList can be used best in case of large and dynamic data set.
How to initialize List<String> object in Java? - Stack Overflow
2012年11月15日 · Just in case, any one still lingering around this question. Because, i see one or two new users again asking the same question and everyone telling then , No you can't do that, Dear Prudence, Apart from all the answers given here, I would like to provide additional Information - Yes you can actually do, List list = new List(); But at the cost of writing …
What are the options to clone or copy a list in Python? - Stack …
@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 …
Get a list from Pandas DataFrame column headers
Create a list of keys/columns - object method to_list() and the Pythonic way: my_dataframe.keys().to_list() list(my_dataframe.keys()) Basic iteration on a DataFrame returns column labels: [column for column in my_dataframe] Do not convert a DataFrame into a list, just to get the column labels.
python - if/else in a list comprehension - Stack Overflow
Since 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.