Reputation: 1720
Assume I have a list of words, and I want to find the number of times each word appears in that list.
An obvious way to do this is:
words = "apple banana apple strawberry banana lemon"
uniques = set(words.split())
freqs = [(item, words.split().count(item)) for item in uniques]
print(freqs)
But I find this code not very good, because the program runs through the word list twice, once to build the set, and a second time to count the number of appearances.
Of course, I could write a function to run through the list and do the counting, but that wouldn't be so Pythonic. So, is there a more efficient and Pythonic way?
Upvotes: 70
Views: 156214
Reputation: 1
Here is my solution. No imports, just a simple nested loop.
words = input().split(" ")
for word in words:
word_count = 0
for word2 in words:
if word2.lower() == word.lower():
word_count += 1
print(f'{word} {word_count}')
Upvotes: 0
Reputation: 1
I had a similar assignment on Zybook, this is the solution that worked for me.
def build_dictionary(words):
counts = dict()
for word in words:
if word in counts:
counts[word] += 1
else:
counts = 1
return counts
if __name__ == '__main__':
words = input().split()
your_dictionary = build_dictionary(words)
sorted_keys = sorted(your_dictionary.keys())
for key in sorted_keys:
print(key + ':' + str(your_dictionary[key]))
Upvotes: 0
Reputation: 1152
Use reduce() to convert the list to a single dict.
from functools import reduce
words = "apple banana apple strawberry banana lemon"
reduce( lambda d, c: d.update([(c, d.get(c,0)+1)]) or d, words.split(), {})
returns
{'strawberry': 1, 'lemon': 1, 'apple': 2, 'banana': 2}
Upvotes: 0
Reputation: 51
list = input() # Providing user input passes multiple tests
text = list.split()
for word in text:
freq = text.count(word)
print(word, freq)
Upvotes: 0
Reputation: 21
user_input = list(input().split(' '))
for word in user_input:
print('{} {}'.format(word, user_input.count(word)))
Upvotes: 2
Reputation: 79
words = "apple banana apple strawberry banana lemon"
w=words.split()
e=list(set(w))
word_freqs = {}
for i in e:
word_freqs[i]=w.count(i)
print(word_freqs)
Hope this helps!
Upvotes: 1
Reputation: 223172
Standard approach:
from collections import defaultdict
words = "apple banana apple strawberry banana lemon"
words = words.split()
result = defaultdict(int)
for word in words:
result[word] += 1
print result
Groupby oneliner:
from itertools import groupby
words = "apple banana apple strawberry banana lemon"
words = words.split()
result = dict((key, len(list(group))) for key, group in groupby(sorted(words)))
print result
Upvotes: 11
Reputation: 101416
The Counter
class in the collections
module is purpose built to solve this type of problem:
from collections import Counter
words = "apple banana apple strawberry banana lemon"
Counter(words.split())
# Counter({'apple': 2, 'banana': 2, 'strawberry': 1, 'lemon': 1})
Upvotes: 152
Reputation: 1
I happened to work on some Spark exercise, here is my solution.
tokens = ['quick', 'brown', 'fox', 'jumps', 'lazy', 'dog']
print {n: float(tokens.count(n))/float(len(tokens)) for n in tokens}
**#output of the above **
{'brown': 0.16666666666666666, 'lazy': 0.16666666666666666, 'jumps': 0.16666666666666666, 'fox': 0.16666666666666666, 'dog': 0.16666666666666666, 'quick': 0.16666666666666666}
Upvotes: 0
Reputation: 34
The answer below takes some extra cycles, but it is another method
def func(tup):
return tup[-1]
def print_words(filename):
f = open("small.txt",'r')
whole_content = (f.read()).lower()
print whole_content
list_content = whole_content.split()
dict = {}
for one_word in list_content:
dict[one_word] = 0
for one_word in list_content:
dict[one_word] += 1
print dict.items()
print sorted(dict.items(),key=func)
Upvotes: -1
Reputation: 11
Can't you just use count?
words = 'the quick brown fox jumps over the lazy gray dog'
words.count('z')
#output: 1
Upvotes: 0
Reputation: 3382
freqs = {}
for word in words:
freqs[word] = freqs.get(word, 0) + 1 # fetch and increment OR initialize
I think this results to the same as Triptych's solution, but without importing collections. Also a bit like Selinap's solution, but more readable imho. Almost identical to Thomas Weigel's solution, but without using Exceptions.
This could be slower than using defaultdict() from the collections library however. Since the value is fetched, incremented and then assigned again. Instead of just incremented. However using += might do just the same internally.
Upvotes: 12
Reputation: 159
Without defaultdict:
words = "apple banana apple strawberry banana lemon"
my_count = {}
for word in words.split():
try: my_count[word] += 1
except KeyError: my_count[word] = 1
Upvotes: 3
Reputation: 212208
defaultdict to the rescue!
from collections import defaultdict
words = "apple banana apple strawberry banana lemon"
d = defaultdict(int)
for word in words.split():
d[word] += 1
This runs in O(n).
Upvotes: 95
Reputation: 28715
If you don't want to use the standard dictionary method (looping through the list incrementing the proper dict. key), you can try this:
>>> from itertools import groupby
>>> myList = words.split() # ['apple', 'banana', 'apple', 'strawberry', 'banana', 'lemon']
>>> [(k, len(list(g))) for k, g in groupby(sorted(myList))]
[('apple', 2), ('banana', 2), ('lemon', 1), ('strawberry', 1)]
It runs in O(n log n) time.
Upvotes: 7