12,133 questions
1270
votes
33
answers
1.6m
views
Get difference between two lists with Unique Entries
I have two lists in Python:
temp1 = ['One', 'Two', 'Three', 'Four']
temp2 = ['One', 'Two']
Assuming the elements in each list are unique, I want to create a third list with items from the first list ...
- 64.8k
854
votes
19
answers
856k
views
How to convert an Array to a Set in Java
I would like to convert an array to a Set in Java. There are some obvious ways of doing this (i.e. with a loop) but I would like something a bit neater, something like:
java.util.Arrays.asList(Object[...
user130076
797
votes
16
answers
702k
views
728
votes
15
answers
1.0m
views
How to retrieve an element from a set without removing it?
Suppose the following:
>>> s = set([1, 2, 3])
How do I get a value (any value) out of s without doing s.pop()? I want to leave the item in the set until I am sure I can remove it - something ...
- 70.8k
661
votes
8
answers
315k
views
Empty set literal?
[] = empty list
() = empty tuple
{} = empty dict
Is there a similar notation for an empty set?
Or do I have to write set()?
- 21.7k
628
votes
15
answers
1.2m
views
Convert Set to List without creating new List
I am using this code to convert a Set to a List:
Map<String, List<String>> mainMap = new HashMap<>();
for (int i=0; i < something.size(); i++) {
Set<String> set = getSet(...
- 23.5k
598
votes
9
answers
833k
views
580
votes
7
answers
540k
views
C# Set collection?
Does anyone know if there is a good equivalent to Java's Set collection in C#? I know that you can somewhat mimic a set using a Dictionary or a HashTable by populating but ignoring the values, but ...
- 56k
514
votes
26
answers
696k
views
What is the difference between Set and List?
What is the fundamental difference between the Set<E> and List<E> interfaces?
- 27.8k
486
votes
12
answers
593k
views
How to check that an element is in a std::set?
How do you check that an element is in a set?
Is there a simpler equivalent of the following code:
myset.find(x) != myset.end()
- 16.1k
447
votes
22
answers
1.1m
views
Getting an element from a Set
Why doesn't Set provide an operation to get an element that equals another element?
Set<Foo> set = ...;
...
Foo foo = new Foo(1, 2, 3);
Foo bar = set.get(foo); // get the Foo element from the ...
- 5,128
446
votes
9
answers
1.2m
views
How to get the first element of the List or Set? [duplicate]
I'd like to know if I can get the first element of a list or set. Which method to use?
- 86.7k
434
votes
13
answers
669k
views
426
votes
7
answers
310k
views
Best way to find the intersection of multiple sets?
I have a list of sets:
setlist = [s1,s2,s3...]
I want s1 ∩ s2 ∩ s3 ...
I can write a function to do it by performing a series of pairwise s1.intersection(s2), etc.
Is there a recommended, better, ...
- 6,024
408
votes
4
answers
314k
views
Golang why don't we have a set datastructure [closed]
I'm trying to solve a Go language exercise which requires me to have a set. I can create a set type but why doesn't the language come with one?
Go, having come from Google, where Guava also originated,...
- 14.2k