I’m trying to set the background color of a View (in this case a Button). I use this code: // set the background to green v.setBackgroundColor(0x0000FF00 ); v.invalidate(); It causes the Button to disappear from the screen. What am I doing wrong, and what is the correct way to change the background color on any … Read more
I have a Python set that contains objects with __hash__ and __eq__ methods in order to make certain no duplicates are included in the collection. I need to json encode this result set, but passing even an empty set to the json.dumps method raises a TypeError. File “/usr/lib/python2.7/json/encoder.py”, line 201, in encode chunks = self.iterencode(o, … Read more
Recently I noticed that when I am converting a list to set the order of elements is changed and is sorted by character. Consider this example: x=[1,2,20,6,210] print(x) # [1, 2, 20, 6, 210] # the order is same as initial order set(x) # set([1, 2, 20, 210, 6]) # in the set(x) output order … Read more
I’ve been trying to set the value of a hidden field in a form using jQuery, but without success. Here is a sample code that explains the problem. If I keep the input type to “text”, it works without any trouble. But, changing the input type to “hidden”, doesn’t work ! <html> <head> <script type=”text/javascript” … Read more
How do I pick a random element from a set? I’m particularly interested in picking a random element from a HashSet or a LinkedHashSet, in Java. Solutions for other languages are also welcome. 34 Answers 34 int size = myHashSet.size(); int item = new Random().nextInt(size); // In real life, the Random object should be rather … Read more
Is there any way to map/reduce/filter/etc a Set in JavaScript or will I have to write my own? Here’s some sensible Set.prototype extensions Set.prototype.map = function map(f) { var newSet = new Set(); for (var v of this.values()) newSet.add(f(v)); return newSet; }; Set.prototype.reduce = function(f,initial) { var result = initial; for (var v of this) … Read more
Assume that S and T are assigned sets. Without using the join operator |, how can I find the union of the two sets? This, for example, finds the intersection: S = {1, 2, 3, 4} T = {3, 4, 5, 6} S_intersect_T = { i for i in S if i in T } … Read more
For example, I am currently doing this: Set<String> setOfTopicAuthors = …. List<String> list = Arrays.asList( setOfTopicAuthors.toArray( new String[0] ) ); Can you beat this ? 6 Answers 6
Does a Java Set retain order? A method is returning a Set to me and supposedly the data is ordered but iterating over the Set, the data is unordered. Is there a better way to manage this? Does the method need to be changed to return something other than a Set? 13 Answers 13
I’ve seen people say that set objects in python have O(1) membership-checking. How are they implemented internally to allow this? What sort of data structure does it use? What other implications does that implementation have? Every answer here was really enlightening, but I can only accept one, so I’ll go with the closest answer to … Read more
