Search results
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
You can define lmap function (on the analogy of python2's imap) that returns list: Then calling lmap instead of map will do the job: lmap(str, x) is shorter by 5 characters (30% in this case) than list(map(str, x)) and is certainly shorter than [str(v) for v in x]. You may create similar functions for filter too.
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 · 518. 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:
Map an if statement in Python. 6. using a conditional and lambda in map. 1. Map and lambda function. 0 ...
Oct 28, 2012 · If you're using a pre-2.7 version of Python, you can use a defaultdict to simplify your code a bit (process is still the same - only difference is that now you don't have to check for the key first - it will 'default' to 0 if a matching key isn't found).
Jun 9, 2017 · for i in F_temps: print(F_temps) <map object at 0x7f9aa050ff28> <map object at 0x7f9aa050ff28> <map object at 0x7f9aa050ff28> <map object at 0x7f9aa050ff28> I am not sure but I think that my solution was possible with Python 2.7,how to change this with 3.5?
Nov 30, 2022 · Second option (using map and defining the formula slightly differently [tuple as input]): #Define the formula with a key value pair (tuple) as input and return value def f_items(items): value = items[1] - items[1] * 0.05 return items[0], value new_prices = dict(map(f_items, prices.items())) print(new_prices) # {'n': 94.05, 'a': 94.05, 'c': 139.65}
If anything, I'd expect this to be slower than, say, inverting the dict with a comprehension, because if you invert the dict Python can plausibly know in advance how many buckets to allocate in the underlying C data structure and create the inverse map without ever calling dictresize, but this approach denies Python that possibility.
Aug 7, 2009 · In the Python 2 language map returns a plain old list, just like list comprehensions do in both languages. The crux is that the return value of map in Python 3 (and imap in Python 2) is not a list - it's an iterator! The elements are consumed when you iterate over an iterator unlike when you iterate over a list.
