Python | Finding relative order of elements in list
Sometimes we have an unsorted list an we wish to find the actual position the elements could be when they would be sorted, i.e we wish to construct the list which could give the position to each element destined if the list was sorted. This has a good application in web development and competitive programming domain. Let’s discuss certain ways in which this can be done.
Method #1 : Using sorted() + index() + list comprehension
All the above function can combine to achieve this particular task. The sorted function returns the sorted order and the indexing is done by the index function. List comprehension does the task of doing for whole list elements and integrating both tasks.
# Python3 code to demonstrate # Finding relative order of elements in list # using sorted() + index() + list comprehension # initializing list test_list = [6, 3, 1, 2, 5, 4] # printing original list print("The original list is : " + str(test_list)) # using sorted() + index() + list comprehension # Finding relative order of elements in list temp = sorted(test_list) res = [temp.index(i) for i in test_list] # printing result print ("The relative ordering list is : " + str(res)) |
chevron_right
filter_none
Output :
The original list is : [6, 3, 1, 2, 5, 4] The relative ordering list is : [5, 2, 0, 1, 4, 3]
Method #2 : Using map() + enumerate() + dictionary comprehension + sorted()
The dictionary comprehension is used in place of list comprehension and the sorted list is formed and the index of actual ordering in sorted list are traversed using enumerate to have key-value pair and then are get by map for all the indices in list.
# Python3 code to demonstrate # Finding relative order of elements in list # using map() + enumerate() + dictionary comprehension + sorted() # initializing list test_list = [6, 3, 1, 2, 5, 4] # printing original list print("The original list is : " + str(test_list)) # using map() + enumerate() + dictionary comprehension + sorted() # Finding relative order of elements in list temp = {val: key for key, val in enumerate(sorted(test_list))} res = list(map(temp.get, test_list)) # printing result print ("The relative ordering list is : " + str(res)) |
chevron_right
filter_none
Output :
The original list is : [6, 3, 1, 2, 5, 4] The relative ordering list is : [5, 2, 0, 1, 4, 3]
Recommended Posts:
- Python | Relative sorted order in Matrix
- Python List Comprehension | Sort even-placed elements in increasing and odd-placed in decreasing order
- Python | Finding frequency in list of tuples
- Python | Finding strings with given substring in list
- Python | Sort list according to other list order
- Python | List Element Count with Order
- Python | Merge List with common elements in a List of Lists
- Python | Add list elements with a multi-list based on index
- Python | Replace elements in second list with index of same element in first list
- Python | Subtract two list elements if element in first list is greater
- Python | Sorting list of lists with similar list elements
- Python | Inserting item in sorted list maintaining order
- Python | Extract unique tuples from list, Order Irrespective
- Python | Maximum sum of elements of list in a list of lists
- Python | Indices of sorted list of list elements
If you like GeeksforGeeks and would like to contribute, you can also write an article using contribute.geeksforgeeks.org or mail your article to contribute@geeksforgeeks.org. See your article appearing on the GeeksforGeeks main page and help other Geeks.
Please Improve this article if you find anything incorrect by clicking on the "Improve Article" button below.
