I found this in the docs: https://docs.python.org/3/tutorial/controlflow.html#for Python’s for statement iterates over the items of any sequence (a list or a string), in the order that they appear in the sequence. If you need to modify the sequence you are iterating over while inside the loop (for example to duplicate selected items), it is recommended … Read more
In Scala you can use scala.util.Random: util.Random.shuffle((1 to 10).toSeq) //Vector(9, 6, 8, 7, 10, 1, 2, 5, 3, 4) util.Random.shuffle(List(‘A’, ‘B’, ‘C’, ‘D’, ‘E’, ‘F’)) //List(B, D, A, E, C, F) Your results may vary…
You could do this using JSTL tags, but the result is not optimal: <%@ taglib prefix=”c” uri=”http://java.sun.com/jsp/jstl/core”%> <html> <body> <jsp:useBean id=”numbers” class=”java.util.HashSet” scope=”request”> <% numbers.add(“one”); numbers.add(“two”); numbers.add(“three”); %> </jsp:useBean> <c:forEach items=”${numbers}” var=”value”> <c:if test=”${value == ‘two’}”> <c:set var=”found” value=”true” scope=”request” /> </c:if> </c:forEach> ${found} </body> </html> A better way would be to use a custom … Read more
Using list comprehension and enumerate: >>> x = [ ‘w’, ‘e’, ‘s’, ‘s’, ‘s’, ‘z’,’z’, ‘s’] >>> [i for i, n in enumerate(x) if n == ‘s’][0] 2 >>> [i for i, n in enumerate(x) if n == ‘s’][1] 3 >>> [i for i, n in enumerate(x) if n == ‘s’][2] 4 >>> [i for … Read more
set_2 = frozenset(list_2) intersection = [x for x in list_1 if x in set_2] set instead of frozenset works too, I’m just increasingly in the habit of using immutable classes in cases where I don’t intend to mutate the data. The point is that to maintain order you need to traverse the list in the … Read more
Let’s look at what the function does for your example input: transpose [[1,2,3],[4,5,6],[7,8,9]] <=> (map head [[1,2,3],[4,5,6],[7,8,9]]) : (transpose (map tail [[1,2,3],[4,5,6],[7,8,9]])) <=> [1,4,7] : (transpose [[2,3],[5,6],[8,9]]) <=> [1,4,7] : (map head [[2,3],[5,6],[8,9]]) : (transpose (map tail [[2,3],[5,6],[8,9]])) <=> [1,4,7] : [2,5,8] : (transpose [[3],[6],[9]]) <=> [1,4,7] : [2,5,8] : (map head [[3],[6],[9]]) : (transpose … Read more
First of all, new List() won’t work, since the List class is abstract. The other two options are defined as follows in the List object: override def empty[A]: List[A] = Nil override def apply[A](xs: A*): List[A] = xs.toList I.e., they’re essentially equivalent, so it’s mostly a matter of style. I prefer to use empty because … Read more
Yes, it is fine to use None, as its behavior is specified by the documentation: The slice of s from i to j is defined as the sequence of items with index k such that i <= k < j. If i or j is greater than len(s), use len(s). If i is omitted or … Read more