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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.
A list of lists named xss can be flattened using a nested list comprehension: flat_list = [ x for xs in xss for x in xs ] The above is equivalent to: flat_list = [] for xs in xss: for x in xs: flat_list.append(x) Here is the corresponding function: def flatten(xss): return [x for xs in xss for x in xs]
float(item) do the right thing: it converts its argument to float and and return it, but it doesn't change argument in-place. A simple fix for your code is: new_list = [] for item in list: new_list.append(float(item)) The same code can written shorter using list comprehension: new_list = [float(i) for i in list]
In python an easy way is: your_list = [] for i in range(10): your_list.append(i) You can also get your for in a single line like so: your_list = [] for i in range(10): your_list.append(i) Don't ever get discouraged by other people's opinions, specially for new learners.
4. There is an inbuilt function called len () in python which will help in these conditions. >>> a = [1,2,3,4,5,6] >>> len(a) # Here the len() function counts the number of items in the list. 6. This will work slightly different in the case of string: it counts the characters. >>> a = "Hello". >>> len(a) 5.
In Python 3, filter doesn't return a list, but a generator-like object. Finding the first occurrence If you only want the first thing that matches a condition (but you don't know what it is yet), it's fine to use a for loop (possibly using the else clause as well, which is not really well-known).
my_list = ['foo','bar','baz','>=','5.2'] # With only_words = [token for token in my_list if token.isalpha()] # Without only_words = filter(str.isalpha, my_list) Personally I don't think you have to use a list comprehension for everything in Python, but I always get frowny-faced when I suggest map or filter answers.
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.
C:\Users\user>pyenv --version pyenv 2.64.11 C:\Users\name>pyenv pyenv 2.64.11 Usage: pyenv <command> [<args>] Some useful pyenv commands are: commands List all available pyenv commands duplicate Creates a duplicate python environment local Set or show the local application-specific Python version global Set or show the global Python version ...
@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.