ConcurrentLinkedQueue If you don’t care about having index-based access and just want the insertion-order-preserving characteristics of a List, you could consider a java.util.concurrent.ConcurrentLinkedQueue. Since it implements Iterable, once you’ve finished adding all the items, you can loop over the contents using the enhanced for syntax: Queue<String> globalQueue = new ConcurrentLinkedQueue<String>(); //Multiple threads can safely call … Read more
In Python 2: >>> list_a = [1, 2, 3, 4] >>> list_b = [5, 6, 7, 8] >>> zip(list_a, list_b) [(1, 5), (2, 6), (3, 7), (4, 8)] In Python 3: >>> list_a = [1, 2, 3, 4] >>> list_b = [5, 6, 7, 8] >>> list(zip(list_a, list_b)) [(1, 5), (2, 6), (3, 7), (4, … Read more
You can use the sequence method list.extend to extend the list by multiple values from any kind of iterable, being it another list or any other thing that provides a sequence of values. >>> lst = [1, 2] >>> lst.append(3) >>> lst.append(4) >>> lst [1, 2, 3, 4] >>> lst.extend([5, 6, 7]) >>> lst.extend((8, 9, … Read more
Adding the contents of a list Use set.update() or the |= operator: >>> a = set(‘abc’) >>> a {‘a’, ‘b’, ‘c’} >>> xs = [‘d’, ‘e’] >>> a.update(xs) >>> a {‘e’, ‘b’, ‘c’, ‘d’, ‘a’} >>> xs = [‘f’, ‘g’] >>> a |= set(xs) >>> a {‘e’, ‘b’, ‘f’, ‘c’, ‘d’, ‘g’, ‘a’} Adding the … Read more
good, bad = [], [] for x in mylist: (bad, good)[x in goodvals].append(x)
It can be done with list comprehensions >>> [x.lower() for x in [“A”, “B”, “C”]] [‘a’, ‘b’, ‘c’] >>> [x.upper() for x in [“a”, “b”, “c”]] [‘A’, ‘B’, ‘C’] or with the map function >>> list(map(lambda x: x.lower(), [“A”, “B”, “C”])) [‘a’, ‘b’, ‘c’] >>> list(map(lambda x: x.upper(), [“a”, “b”, “c”])) [‘A’, ‘B’, ‘C’]
next((x for x in test_list if x.value == value), None) This gets the first item from the list that matches the condition, and returns None if no item matches. It’s my preferred single-expression form. However, for x in test_list: if x.value == value: print(“i found it!”) break The naive loop-break version, is perfectly Pythonic — … Read more
Ultimately it probably doesn’t have a safe .get method because a dict is an associative collection (values are associated with names) where it is inefficient to check if a key is present (and return its value) without throwing an exception, while it is super trivial to avoid exceptions accessing list elements (as the len method … Read more
In Java terms, Scala’s Seq would be Java’s List, and Scala’s List would be Java’s LinkedList. Note that Seq is a trait, which is equivalent to Java’s interface, but with the equivalent of up-and-coming defender methods. Scala’s List is an abstract class that is extended by Nil and ::, which are the concrete implementations of … Read more
This actually removes the contents from the list, but doesn’t replace the old label with a new empty list: del lst[:] Here’s an example: lst1 = [1, 2, 3] lst2 = lst1 del lst1[:] print(lst2) For the sake of completeness, the slice assignment has the same effect: lst[:] = [] It can also be used … Read more