How would I find how many times each string appears in my list?
Say I have the word:
"General Store"
that is in my list like 20 times. How would I find out that it appears 20 times in my list? I need to know this so I can display that number as a type of "poll vote" answer.
E.g:
General Store - voted 20 times
Mall - voted 50 times
Ice Cream Van - voted 2 times
How would I display it in a fashion similar to this?:
General Store
20
Mall
50
Ice Cream Van
2
While the other answers (using list.count) do work, they can be prohibitively slow on large lists.
Consider using collections.Counter, as describe in http://docs.python.org/library/collections.html
Example:
>>> # Tally occurrences of words in a list
>>> cnt = Counter()
>>> for word in ['red', 'blue', 'red', 'green', 'blue', 'blue']:
... cnt[word] += 1
>>> cnt
Counter({'blue': 3, 'red': 2, 'green': 1})
cnt = Counter(['red','blue','red','green','blue','blue']) ? As it is, you might as well be using cnt = defaultdict(int) -- which I suppose provides an O(N) way to do this in python 2.5 ... (as opposed to 2.7+ when Counter was introduced.)
Counter([iterable]) constructor is definitely cleaner and simpler!just a simple example:
>>> lis=["General Store","General Store","General Store","Mall","Mall","Mall","Mall","Mall","Mall","Ice Cream Van","Ice Cream Van"]
>>> for x in set(lis):
print "{0}\n{1}".format(x,lis.count(x))
Mall
6
Ice Cream Van
2
General Store
3
First use set() to get all unique elements of the list. Then loop over the set to count elements from the list
unique = set(votes)
for item in unique:
print item
print votes.count(item)
I like one-line solutions to problems like this:
def tally_votes(l):
return map(lambda x: (x, len(filter(lambda y: y==x, l))), set(l))
You can use a dictionary, you might want to consider just using a dictionary from the beginning instead of a list but here is a simple setup.
#list
mylist = ['General Store','Mall','Ice Cream Van','General Store']
#takes values from list and create a dictionary with the list value as a key and
#the number of times it is repeated as their values
def votes(mylist):
d = dict()
for value in mylist:
if value not in d:
d[value] = 1
else:
d[value] +=1
return d
#prints the keys and their vaules
def print_votes(dic):
for c in dic:
print c +' - voted', dic[c], 'times'
#function call
print_votes(votes(mylist))
It outputs:
Mall - voted 1 times
Ice Cream Van - voted 1 times
General Store - voted 2 times
If you're willing to use the pandas library, this one is really quick:
import pandas as pd
my_list = lis=["General Store","General Store","General Store","Mall","Mall","Mall","Mall","Mall","Mall","Ice Cream Van"]
pd.Series(my_list).value_counts()
votes=["General Store", "Mall", "General Store","Ice Cream Van","General Store","Ice Cream Van","Ice Cream Van","General Store","Ice Cream Van"]
for vote in set(votes):
print(vote+" - voted "+str(votes.count(vote))+" times")
Try this. It will output
General Store - voted 4 times
Ice Cream Van - voted 4 times
Mall - voted 1 times