How to find most common elements of a list? [duplicate]

by

In Python 2.7 and above there is a class called Counter which can help you:

from collections import Counter
words_to_count = (word for word in word_list if word[:1].isupper())
c = Counter(words_to_count)
print c.most_common(3)

Result:

[('Jellicle', 6), ('Cats', 5), ('And', 2)]

I am quite new to programming so please try and do it in the most barebones fashion.

You could instead do this using a dictionary with the key being a word and the value being the count for that word. First iterate over the words adding them to the dictionary if they are not present, or else increasing the count for the word if it is present. Then to find the top three you can either use a simple O(n*log(n)) sorting algorithm and take the first three elements from the result, or you can use a O(n) algorithm that scans the list once remembering only the top three elements.

An important observation for beginners is that by using builtin classes that are designed for the purpose you can save yourself a lot of work and/or get better performance. It is good to be familiar with the standard library and the features it offers.

More Related Contents:

  1. Count frequency of words in a list and sort by frequency
  2. Sort list by frequency
  3. What does “list comprehension” and similar mean? How does it work and how can I use it?
  4. What’s the difference between lists and tuples?
  5. How to remove list elements in a for loop in Python? [duplicate]
  6. Element-wise addition of 2 lists?
  7. Iterate over all pairs of consecutive items in a list [duplicate]
  8. How Big can a Python List Get?
  9. Sum a list of numbers in Python
  10. How to group a list of tuples/objects by similar index/attribute in python?
  11. How to force a list to a fixed size?
  12. What is the inverse function of zip in python? [duplicate]
  13. Pandas expand rows from list data available in column
  14. How to check if an object is a list or tuple (but not string)?
  15. How to remove all duplicate items from a list [duplicate]
  16. Unpack list to variables
  17. Python using enumerate inside list comprehension
  18. How to find common elements in list of lists?
  19. How to convert a string list into an integer in python [duplicate]
  20. Convert list of strings to dictionary
  21. Most efficient way for a lookup/search in a huge list (python)
  22. Sort list of strings by a part of the string
  23. How to make a completely unshared copy of a complicated list? (Deep copy is not enough)
  24. How can I partition (split up, divide) a list based on a condition?
  25. Python: Rename duplicates in list with progressive numbers without sorting list
  26. Loop through list with both content and index [duplicate]
  27. In Python, is there an elegant way to print a list in a custom format without explicit looping?
  28. Retrieve the two highest item from a list containing 100,000 integers
  29. Python find list lengths in a sublist
  30. Python: Random numbers into a list

Leave a Comment