The difference between these two cases are explained when also taking into consideration the initial PEP for extended unpacking: PEP 3132 — Extended iterable unpacking. In the Abstract for that PEP we can see that: This PEP proposes a change to iterable unpacking syntax, allowing to specify a “catch-all” name which will be assigned a … Read more
Calls to itertools.imap() in Python 2 or map() in Python 3 can be replaced by equivalent generator expressions: sum(1 for dummy in it) This also uses a lazy generator, so it avoids materializing a full list of all iterator elements in memory.
What is the real definition of a Javascript iterable using the term as the ES6 specification does? §25.1.1.1 defines “The Iterable Interface”. They’re objects with a Symbol.iterator-keyed method that returns a valid Iterator (which in turn is an object expected to behave as it should according to §25.1.1.2). How do you test for it in … Read more
Most likely the reason for this is because iterators are not reusable; you need to get a fresh Iterator from the Iterable collection each time you want to iterate over the elements. However, as a quick fix: private static <T> Iterable<T> iterable(final Iterator<T> it){ return new Iterable<T>(){ public Iterator<T> iterator(){ return it; } }; } … Read more
Your problem is with this line: number4 = list(cow[n]) It tries to take cow[n], which returns an integer, and make it a list. This doesn’t work, as demonstrated below: >>> a = 1 >>> list(a) Traceback (most recent call last): File “<stdin>”, line 1, in <module> TypeError: ‘int’ object is not iterable >>> Perhaps you … Read more
Looks like that is the best way to do it: String first = strs.iterator().next(); Great question… At first, it seems like an oversight for the Collection interface. Note that “first” won’t always return the first thing you put in the collection, and may only make sense for ordered collections. Maybe that is why there isn’t … Read more
This was not an omission; there was detailed discussion on the EG list in June of 2013. The definitive discussion of the Expert Group is rooted at this thread. While it seemed “obvious” (even to the Expert Group, initially) that stream() seemed to make sense on Iterable, the fact that Iterable was so general became … Read more
__iter__ is what gets called when you try to iterate over a class instance: >>> class Foo(object): … def __iter__(self): … return (x for x in range(4)) … >>> list(Foo()) [0, 1, 2, 3] __next__ is what gets called on the object which is returned from __iter__ (on python2.x, it’s next, not __next__ — I … Read more
You can use Array.from or spread syntax (…). Example: const x = new Set([ 1, 2, 3, 4 ]); const y = Array.from(x); console.log(y); // = [ 1, 2, 3, 4 ] const z = [ …x ]; console.log(z); // = [ 1, 2, 3, 4 ]
In JDK 8+, without using any additional libs: Iterator<T> source = …; List<T> target = new ArrayList<>(); source.forEachRemaining(target::add); Edit: The above one is for Iterator. If you are dealing with Iterable, iterable.forEach(target::add);