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Jun 11, 2012 · In Python 2 map(), will iterate (go through the elements of the lists) according to the longest list, and pass None to the function for the shorter lists, so your function should look for None and handle them, otherwise you will get errors. In Python 3 map() will stop after finishing with the shortest
we want to apply map function for an array. map(add, [1, 2, 3], 2) The semantics are I want to add 2 to every element of the array. But the map function requires a list in the third argument as well. Note: I am putting the add example for simplicity. My original function is much more complicated.
EDIT: I didn't realize that map equals itertools.imap after python 3.0. So the conclusion here may not be correct. I'll re-run the test on python 2.6 tomorrow and post result. If doSomething is very "tiny", map can be a lot faster than for loop or a list-comprehension:
Sep 1, 2012 · 520. There is no such function; the easiest way to do this is to use a dict comprehension: my_dictionary = {k: f(v) for k, v in my_dictionary.items()} Note that there is no such method on lists either; you'd have to use a list comprehension or the map() function. As such, you could use the map() function for processing your dict as well:
Note that as you don't need the result of filtered list and you just want to pass it to map it's more efficient that use ifilter because it returns a generator and you can save much memory for long lists ;) (its all in python 2 and in python 3 filter returns generator)
Jul 15, 2016 · There's a fork of multiprocessing called pathos (note: use the version on GitHub) that doesn't need starmap-- the map functions mirror the API for Python's map, thus map can take multiple arguments. With pathos , you can also generally do multiprocessing in the interpreter, instead of being stuck in the __main__ block.
Feb 5, 2016 · Here are some simple tests to compare three methods to map a function, this example using with Python 3.6 and NumPy 1.15.4. First, the set-up functions for testing:
For example, to lowercase all strings in a list, you can use: map(str.lower, list_of_strings) where str.lower is the unbound method on the str type. Note that a list comprehension is not really the equivalent of a map() here. map() can only do one loop, entirely in C. map() will zip() multiple iterable arguments, and map() in Python 3 is itself ...
Jun 9, 2014 · You will notice that Python has some other functional programming functions such as reduce, filter, zip etc. map is part of this class of functions where although each implements a very simple function, when you combine these into a single statement you can get very powerful results.
If the original case is upper then the list s will contain lowercase of the respective item in list p. If the original case of the list item is already lowercase in list p then the list s will retain the item's case and keep it in lowercase. Now you can use list s instead of list p. edited May 31, 2018 at 8:42.
