I had a task that I only knew the length of the array and needed to transform the items. I wanted to do something like this: let arr = new Array(10).map((val,idx) => idx); To quickly create an array like this: [0,1,2,3,4,5,6,7,8,9] But it didn’t work because: (see Jonathan Lonowski’s answer) The solution could be to … Read more
One argument that is repeated, one argument in c from itertools import repeat for result in executor.map(f, repeat(a), c): pass Need to unpack items of c, and can unpack c from itertools import izip for result in executor.map(f, *izip(*c)): pass Need to unpack items of c, can’t unpack c Change f to take a single … Read more
Since Java 8, there are some standard options to do this in JDK: Collection<E> in = … Object[] mapped = in.stream().map(e -> doMap(e)).toArray(); // or List<E> mapped = in.stream().map(e -> doMap(e)).collect(Collectors.toList()); See java.util.Collection.stream() and java.util.stream.Collectors.toList().
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()} In python 2.7, use the .iteritems() method instead of .items() to save memory. The dict comprehension syntax wasn’t introduced until python 2.7. Note that there is no such method … Read more
The short answer: the built-in function arrayfun does exactly what your map function does for numeric arrays: >> y = arrayfun(@(x) x^2, 1:10) y = 1 4 9 16 25 36 49 64 81 100 There are two other built-in functions that behave similarly: cellfun (which operates on elements of cell arrays) and structfun (which … Read more
I like your reduce version just fine. I think it’s idiomatic. Here’s a version using list comprehension anyways. (defn foo [m f] (into {} (for [[k v] m] [k (f v)])))
You can use functools.partial for this (as you suspected): from functools import partial def target(lock, iterable_item): for item in iterable_item: # Do cool stuff if (… some condition here …): lock.acquire() # Write to stdout or logfile, etc. lock.release() def main(): iterable = [1, 2, 3, 4, 5] pool = multiprocessing.Pool() l = multiprocessing.Lock() func … Read more
Why do generators not support map()? Because it’s too easy to fill in as a userland implementation. ES3 didn’t include Array iteration methods either, maybe will see transformers for iterators in ES7 🙂 generators, which function very much like Arrays No, please stop and distinguish iterators from generators: An iterator is an object with a … Read more
There is a map method in multiprocessing.Pool. That does multiple processes. And if multiple processes aren’t your dish, you can use multiprocessing.dummy which uses threads. import urllib import multiprocessing.dummy p = multiprocessing.dummy.Pool(5) def f(post): return urllib.urlopen(‘http://stackoverflow.com/questions/%u’ % post) print p.map(f, range(3329361, 3329361 + 5))
Use functools.partial(): from functools import partial mapfunc = partial(my_function, ip=ip) map(mapfunc, volume_ids) partial() creates a new callable, that’ll apply any arguments (including keyword arguments) to the wrapped function in addition to whatever is being passed to that new callable.