The whole point of using Maps is direct access. If you know for sure that the value in a map will never be Groovy-false, then you can do this: def mymap = [name:”Gromit”, likes:”cheese”, id:1234] def key = “likes” if(mymap[key]) { println mymap[key] } However, if the value could potentially be Groovy-false, you should use: … Read more
This works: (apply str my-char-seq) Basically, str calls toString() on each of its args and then concatenates them. Here we are using apply to pass the characters in the sequence as args to str.
That looks like a perfectly fine way to do this to me. I don’t think copying one map into another is common enough to have a one-liner solution.
The definition for Dictionary is struct Dictionary<KeyType : Hashable, ValueType> : …, i.e. the type of the key must conform to the protocol Hashable. But the language guide tells us that protocols can be adopted by classes, structs and enums, i.e. not by tuples. Therefore, tuples cannot be used as Dictionary keys. A workaround would … Read more
var usdKey = curr.keys.firstWhere( (k) => curr[k] == ‘USD’, orElse: () => null);
Whether getting an arbitrary key from a hash table is a common requirement may be discussed. Other language map implementations often lack this feature (eg. Dictionary in C# ) However, your solution is probably the fastest one, but you will be left with a pseudo-random algorithm that you do not control. And while the current … Read more
Returning a Map result using JPA Query getResultStream Since the JPA 2.2 version, you can use the getResultStream Query method to transform the List<Tuple> result into a Map<Integer, Integer>: Map<Integer, Integer> postCountByYearMap = entityManager.createQuery(“”” select YEAR(p.createdOn) as year, count(p) as postCount from Post p group by YEAR(p.createdOn) “””, Tuple.class) .getResultStream() .collect( Collectors.toMap( tuple -> ((Number) … Read more
The zero value for map types is nil. It is not yet initialized. You cannot store values in a nil map, that’s a runtime panic. In your last example you initialize the (outer) data map, but it has no entries. When you index it like data[“a”], since there is no entry with “a” key in … Read more
You can do: val map = hashMapOf( “John” to “Doe”, “Jane” to “Smith” ) Here, to is an infix function that creates a Pair. Or, more abstract: use mapOf() like val map = mapOf(“a” to 1, “b” to 2, “c” to 3) ( found on kotlinlang )
You can pass the dict of dict to the DataFrame constructor: In [11]: d = {‘Jill’: {‘Django Unchained’: 6.5, ‘Gone Girl’: 9.0, ‘Kill the Messenger’: 8.0, ‘Avenger: Age of Ultron’: 7.0}, ‘Toby’: {‘Django Unchained’: 9.0, ‘Zoolander’: 2.0, ‘Avenger: Age of Ultron’: 8.5}} In [12]: pd.DataFrame(d) Out[12]: Jill Toby Avenger: Age of Ultron 7.0 8.5 Django … Read more