Sorting tuples in python based on their values [duplicate]

Question

I am trying to print the top 10 frequent words using the following code. However, its not working. Any idea on how to fix it?

def reducer_count_words(self, word, counts): # send all (num_occurrences, word) pairs to the same reducer. # num_occurrences is so we can easily use Python's max() function. yield None, (sum(counts), word) # discard the key; it is just None def reducer_find_max_10_words(self, _, word_count_pairs): # each item of word_count_pairs is (count, word), # so yielding one results in key=counts, value=word tmp = sorted(word_count_pairs)[0:10] yield tmp

@Veedrac: more similar to this question: stackoverflow.com/questions/3121979/… — Leftium
– Leftium, Commented May 28, 2014 at 19:45
@Leftium I strongly disagree with your interpretation of the question. Also, how the hell did "its not working. Any idea on how to fix it?" get upvotes? — Veedrac
– Veedrac, Commented May 28, 2014 at 19:49
@Veedrac: my interpretation is based on the question title and the asker's responses to other answers. — Leftium
– Leftium, Commented May 28, 2014 at 19:58
@Leftium I stick by my opinion, but I don't really care about a question of this quality anyway. — Veedrac
– Veedrac, Commented May 28, 2014 at 20:00

BeetDemGuise · Accepted Answer · 2014-05-28 19:38:56Z

2

Use collections.Counter and its most_common method:

>>>from collections import Counter >>>my_words = 'a a foo bar foo' >>>Counter(my_words.split()).most_common() [('foo', 2), ('a', 2), ('b', 1)]

edited May 28, 2014 at 19:38

answered May 28, 2014 at 18:10

BeetDemGuise

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2 Comments

A.M. Over a year ago

I am using this command in my code but seeing this error: unhashable type 'list'. If I want to use this format it seems like I cannot use most.common()

BeetDemGuise Over a year ago

Hmm. That exact code works on my machine.

johntellsall · Accepted Answer · 2014-05-28 18:15:57Z

Use collections.most_common()

Example:

most_common([n]) Return a list of the n most common elements and their counts from the most common to the least. If n is not specified, most_common() returns all elements in the counter. Elements with equal counts are ordered arbitrarily: >>> from collections import Counter >>> Counter('abracadabra').most_common(3) [('a', 5), ('r', 2), ('b', 2)]

I am using this command in my code but seeing this error: unhashable type 'list'. If I want to use this format it seems like I cannot use most.common()
Run most_common() on the list of words, not on the (word, count) tuples

Leftium · Accepted Answer · 2014-05-28 19:42:19Z

tmp = sorted(word_count_pairs, key=lambda pair: pair[0], reverse=True)[0:10]

Explanation:

The key parameter of sorted() allows you to run a function on each element before comparison.
lambda pair: pair[0] is a function that extracts the number from your word_count_pairs.
reverse sorts in descending order, instead of ascending order.

Sources:

aside: If you have many different words, sorting the entire list to find the top ten is inefficient. There are much more efficient algorithms. The most_common() method mentioned in another answers probably utilizes a more efficient algorithm.

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