Either: Foo[] array = list.toArray(new Foo[0]); or: Foo[] array = new Foo[list.size()]; list.toArray(array); // fill the array Note that this works only for arrays of reference types. For arrays of primitive types, use the traditional way: List<Integer> list = …; int[] array = new int[list.size()]; for(int i = 0; i < list.size(); i++) array[i] = … Read more
Objects in JavaScript can be thought of as associative arrays, mapping keys (properties) to values. To remove a property from an object in JavaScript you use the delete operator: const o = { lastName: ‘foo’ } o.hasOwnProperty(‘lastName’) // true delete o[‘lastName’] o.hasOwnProperty(‘lastName’) // false Note that when delete is applied to an index property of … Read more
If you’d like a version on npm, array-move is the closest to this answer, although it’s not the same implementation. See its usage section for more details. The previous version of this answer (that modified Array.prototype.move) can be found on npm at array.prototype.move. I had fairly good success with this function: function array_move(arr, old_index, new_index) … Read more
You really don’t need jQuery for this. var myarr = [“I”, “like”, “turtles”]; var arraycontainsturtles = (myarr.indexOf(“turtles”) > -1); Hint: indexOf returns a number, representing the position where the specified searchvalue occurs for the first time, or -1 if it never occurs or function arrayContains(needle, arrhaystack) { return (arrhaystack.indexOf(needle) > -1); } It’s worth noting … Read more
if no such option exists, then maybe there is a nice idiomatic one-liner for doing that ? like, using for…of, or similar ? Indeed, there are several ways to convert a Set to an Array: Using Array.from: Note: safer for TypeScript. const array = Array.from(mySet); Simply spreading the Set out in an array: Note: Spreading … Read more
It is rare, in reality, that you would want to use an array. Definitely use a List<T> any time you want to add/remove data, since resizing arrays is expensive. If you know the data is fixed length, and you want to micro-optimise for some very specific reason (after benchmarking), then an array may be useful. … Read more
If you are using ES6/ES2015 or later you can do it this way: const data = [ { group: ‘A’, name: ‘SD’ }, { group: ‘B’, name: ‘FI’ }, { group: ‘A’, name: ‘MM’ }, { group: ‘B’, name: ‘CO’} ]; const unique = […new Set(data.map(item => item.group))]; // [ ‘A’, ‘B’] Here is an … Read more
With streams added in Java 8 we can write code like: int[] example1 = list.stream().mapToInt(i->i).toArray(); // OR int[] example2 = list.stream().mapToInt(Integer::intValue).toArray(); Thought process: The simple Stream#toArray returns an Object[] array, so it is not what we want. Also, Stream#toArray(IntFunction<A[]> generator) doesn’t do what we want, because the generic type A can’t represent the primitive type … Read more
numpy.savetxt saves an array to a text file. import numpy a = numpy.asarray([ [1,2,3], [4,5,6], [7,8,9] ]) numpy.savetxt(“foo.csv”, a, delimiter=”,”)
ECMAScript 6 introduces the easily polyfillable Object.assign: The Object.assign() method is used to copy the values of all enumerable own properties from one or more source objects to a target object. It will return the target object. Object.assign({}, [‘a’,’b’,’c’]); // {0:”a”, 1:”b”, 2:”c”} The own length property of the array is not copied because it … Read more