duplicates

I have a list with duplicate elements: list_a=[1,2,3,5,6,7,5,2] tmp=[] for i in list_a: if tmp.__contains__(i): print i else: tmp.append(i) I have used the above code to find the duplicate elements in the list_a . I don't want to remove the elements from list. But I want to use for loop here. Normally C/C++ we use like this I guess: for (int i=0;i<=list_a.length;i++) for (int j=i+1;j<=list_a.length;j++) if (list_a[i]==list_a[j]) print list_a[i] how do we use like this in Python? for i in list_a: for j in list_a[1:]: .... I tried the above code. But it gets solution wrong. I don't know how to

I'm having a List<string> like: List<String> list = new List<String>{"6","1","2","4","6","5","1"}; I need to get the duplicate items in the list into a new list. Now I'm using a nested for loop to do this. The resulting list will contain {"6","1"} . Is there any idea to do this using LINQ or lambda expressions ? Lee var duplicates = lst.GroupBy(s => s) .SelectMany(grp => grp.Skip(1)); Note that this will return all duplicates, so if you only want to know which items are duplicated in the source list, you could apply Distinct to the resulting sequence or use the solution given by Mark Byers.

For example, given the list ['one', 'two', 'one'] , the algorithm should return True , whereas given ['one', 'two', 'three'] it should return False . Denis Otkidach Use set() to remove duplicates if all values are hashable : >>> your_list = ['one', 'two', 'one'] >>> len(your_list) != len(set(your_list)) True Recommended for short lists only: any(thelist.count(x) > 1 for x in thelist) Do not use on a long list -- it can take time proportional to the square of the number of items in the list! For longer lists with hashable items (strings, numbers, &c): def anydup(thelist): seen = set() for x in

Suppose I have a file similar to the following: 123 123 234 234 123 345 I would like to find how many times '123' was duplicated, how many times '234' was duplicated, etc. So ideally, the output would be like: 123 3 234 2 345 1 wonk0 Assuming there is one number per line: sort <file> | uniq -c You can use the more verbose --count flag too with the GNU version, e.g., on Linux: sort <file> | uniq --count Andrea This will print duplicate lines only , with counts: sort FILE | uniq -cd or, with GNU long options (on Linux): sort FILE | uniq --count --repeated on BSD and OSX you have to use grep to