There are lies, damned lies and then there is Python documentation. Having __getitem__ for a class implemented in C is not enough for it to be iterable. That is because there are actually 2 places in the PyTypeObject where the __getitem__ can be mapped to: tp_as_sequence and tp_as_mapping. Both have a slot for __getitem__ ([1], … Read more
You can just use iterators: fn main() { let v1 = (0u32..9).filter(|x| x % 2 == 0).map(|x| x.pow(2)).collect::<Vec<_>>(); let v2 = (1..10).filter(|x| x % 2 == 0).collect::<Vec<u32>>(); println!(“{:?}”, v1); // [0, 4, 16, 36, 64] println!(“{:?}”, v2); // [2, 4, 6, 8] }
Due to PEP 585 – Type Hinting Generics In Standard Collections, Python’s standard library container types are also able to accept a generic argument for type annotations. This includes the collections.abc.Iterable class. When supporting only Python 3.9 or later, there is no longer any reason to use the typing.Iterable at all and importing any of … Read more
A Collection is an Iterable. So you can write: public static void main(String args[]) { List<String> list = new ArrayList<String>(); list.add(“a string”); Iterable<String> iterable = list; for (String s : iterable) { System.out.println(s); } }
As an easy and clean way of using an Enumeration with the enhanced for loop, convert to an ArrayList with java.util.Collections.list. for (TableColumn col : Collections.list(columnModel.getColumns()) { (javax.swing.table.TableColumnModel.getColumns returns Enumeration.) Note, this may be very slightly less efficient.
Python 3 If you don’t care about the order of the content, you have the assertCountEqual(a,b) method If you care about the order of the content, you have the assertSequenceEqual(a,b) method Python >= 2.7 If you don’t care about the order of the content, you have the assertItemsEqual(a,b) method If you care about the order … Read more
Programming Practices for Readabililty In general, if you feel like code is not self-describing, the usual solution is to factor it out into a well-named function: def first(s): ”’Return the first element from an ordered collection or an arbitrary element from an unordered collection. Raise StopIteration if the collection is empty. ”’ return next(iter(s)) With … Read more
There is also the all function which does the opposite of what you want, it returns True if all are True and False if any are False. Therefore you can just do: not all(l)
So I have a somewhat reasonable explanation now: Short version: Because the syntax also applies to arrays, which don’t have iterators. If the syntax were designed around Iterator as I proposed, it would be inconsistent with arrays. Let me give three variants: A) as chosen by the Java developers: Object[] array; for(Object o : array) … 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.