How to Check If There Are Duplicates in a Flat List

How do I check if there are duplicates in a flat list?

Use set() to remove duplicates if all values are hashable:

>>> your_list = ['one', 'two', 'one']
>>> len(your_list) != len(set(your_list))
True

How to check if a list contains duplicate items?

As said by Jkdc, convert it to a set and compare the length

lst = ["1","2","3","3","4"]

if len(set(lst)) == len(lst):
    print("success")
else:
    print("duplicate found")

C# Determine Duplicate in List

Unless I'm missing something, then you should be able to get away with something simple using Distinct(). Granted it won't be the most complex implementation you could come up with, but it will tell you if any duplicates get removed:

var list = new List<string>();

// Fill the list

if(list.Count != list.Distinct().Count())
{
     // Duplicates exist
}

How to find duplicates in a list of list of objects in java

Actually, you have:

List<List<String>> compositeKeyValues;

Lists are equal if they have the same elements in the same order - like your example.

Finding duplicate inner Lists is no different finding duplicates of other simpler types.

Here's one way:

List<List<String>> duplicates = compositeKeyValues.stream()
    .collect(Collectors.groupingBy(Function.identity(), Collectors.counting()))
    .entrySet().stream()
    .filter(e -> e.getValue().intValue() > 1)
    .map(Map.Entry::getKey)
    .collect(Collectors.toList());

This code will work even if you leave the type of the List as List<Object>, except the result would also have type List<Object>. However, it's recommended, and more useful, to use a more specific type List<List<String>>.

R - Finding duplicates in list entries

You can unlist first:

unlisted <- unlist(examplelist)
unlisted[duplicated(unlisted)]
#     b1      c1      c2 
#  "red" "black" "green" 

unlisted[!duplicated(unlisted)]
#      a1       a2       a3       b2       b3       c3 
#  "blue"    "red" "yellow"  "black"  "green"  "brown" 

If you only want the vector (without the names), use unname:

unlisted <- unname(unlist(examplelist))

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