Python：计算字符串中列表项的出现次数

Question

If I have the following list

vowels = ["a","e","i","o","u"]

and another list

words = ["happiness", "yellow"]

how do I count the number of vowels in each word, ie happiness = 3, yellow=2?

Answer 1

Using list comprehension:

>>> vowels = ["a","e","i","o","u"]
>>> words = ["happiness", "yellow"]
>>> [sum(c in vowels for c in word) for word in words]
[3, 2]

If you want mapping between the words and occurences, use dictionary comprehension:

>>> {word: sum(c in vowels for c in word) for word in words}
{'happiness': 3, 'yellow': 2}

Converting vowels to set will make it more effective.

Answer 2

data = [0]*len(words)                # Initializing the data list
for index, word in enumerate(words): # Iterating through the list of words
 for letter in list(word):
  if letter in vowels:               #checking if the letter is in vowels
   data[index] = data[index]+1
print data

data now contains number of vowels corresponding to the same index as the words list. Cheers! :)