In terms of performance in Python, is a list-comprehension, or functions like map(), filter() and reduce() faster than a for loop? Why, technically, they run in a C speed, while the for loop runs in the python virtual machine speed?. Suppose that in a game that I’m developing I need to draw complex and huge … Read more
Ok this is more of a computer science question, than a question based on a particular language, but is there a difference between a map operation and a foreach operation? Or are they simply different names for the same thing? 9 Answers 9
I’ve observed this in Firefox-3.5.7/Firebug-1.5.3 and Firefox-3.6.16/Firebug-1.6.2 When I fire up Firebug: var x = new Array(3) console.log(x) // [undefined, undefined, undefined] var y = [undefined, undefined, undefined] console.log(y) // [undefined, undefined, undefined] console.log( x.constructor == y.constructor) // true console.log( x.map(function() { return 0; }) ) // [undefined, undefined, undefined] console.log( y.map(function() { return 0; … Read more
Given a dictionary { k1: v1, k2: v2 … } I want to get { k1: f(v1), k2: f(v2) … } provided I pass a function f. Is there any such built in function? Or do I have to do dict([(k, f(v)) for (k, v) in my_dictionary.iteritems()]) Ideally I would just write my_dictionary.map_values(f) or my_dictionary.mutate_values_with(f) … Read more
map(function, iterable, …) Apply function to every item of iterable and return a list of the results. If additional iterable arguments are passed, function must take that many arguments and is applied to the items from all iterables in parallel. If one iterable is shorter than another it is assumed to be extended with None … Read more
I’m trying to map a list into hex, and then use the list elsewhere. In python 2.6, this was easy: A: Python 2.6: >>> map(chr, [66, 53, 0, 94]) [‘B’, ‘5’, ‘\x00’, ‘^’] However, in Python 3.1, the above returns a map object. B: Python 3.1: >>> map(chr, [66, 53, 0, 94]) <map object at … Read more
Is there a reason to prefer using map() over list comprehension or vice versa? Is either of them generally more efficient or considered generally more pythonic than the other? 14 s 14 map may be microscopically faster in some cases (when you’re NOT making a lambda for the purpose, but using the same function in … Read more
I have an object: myObject = { ‘a’: 1, ‘b’: 2, ‘c’: 3 } I am looking for a native method, similar to Array.prototype.map that would be used as follows: newObject = myObject.map(function (value, label) { return value * value; }); // newObject is now { ‘a’: 1, ‘b’: 4, ‘c’: 9 } Does JavaScript … Read more
