CODEWITHSUNDEEP
pythonlistpython-3.x
Bob
Bob

Reputation: 1396

Items from List to Set by Indexing

Given a list,

a_list=['chicken','pizza','burger','beer','vodka','potato','fries','mustache']

I'm attempting to make a new set of each six word phrase...

a_set=(['chicken','pizza','burger','beer','vodka','potato'],['pizza','burger','beer','vodka','potato','fries],['burger','beer','vodka','potato','fries','mustache'])

I'm attempting to do this by indexing..

index1=0
index2=6
a_set=[]
while True:
    a_set.append(a_list[index1:index2])
    index1+=1
    index2+=1
print (a_set)

I can't seem to figure out what I'm doing wrong. Also, how would I go about ending the loop once it has gone through and created all of the six word phrases and gotten to the end of the list so that it doesn't start from the beginning and do it all again? Thanks for any and all help.

Upvotes: 0

Views: 63

Answers (3)

mata
mata

Reputation: 69042

If I understand you correctly, you want all the possible combinations of six items of your list. itertools.combinations should make this very easy:

>>> import itertools
>>> a_list=['chicken','pizza','burger','beer','vodka','potato','fries','mustache']
>>> a_set=set(itertools.combinations(a_list, 6))
>>> pprint(a_set)
{('burger', 'beer', 'vodka', 'potato', 'fries', 'mustache'),
 ('chicken', 'beer', 'vodka', 'potato', 'fries', 'mustache'),
 ('chicken', 'burger', 'beer', 'potato', 'fries', 'mustache'),
 ('chicken', 'burger', 'beer', 'vodka', 'fries', 'mustache'),
 ('chicken', 'burger', 'beer', 'vodka', 'potato', 'fries'),
 ('chicken', 'burger', 'beer', 'vodka', 'potato', 'mustache'),
 ('chicken', 'burger', 'vodka', 'potato', 'fries', 'mustache'),
 ('chicken', 'pizza', 'beer', 'potato', 'fries', 'mustache'),
 ('chicken', 'pizza', 'beer', 'vodka', 'fries', 'mustache'),
 ('chicken', 'pizza', 'beer', 'vodka', 'potato', 'fries'),
 ('chicken', 'pizza', 'beer', 'vodka', 'potato', 'mustache'),
 ('chicken', 'pizza', 'burger', 'beer', 'fries', 'mustache'),
 ('chicken', 'pizza', 'burger', 'beer', 'potato', 'fries'),
 ('chicken', 'pizza', 'burger', 'beer', 'potato', 'mustache'),
 ('chicken', 'pizza', 'burger', 'beer', 'vodka', 'fries'),
 ('chicken', 'pizza', 'burger', 'beer', 'vodka', 'mustache'),
 ('chicken', 'pizza', 'burger', 'beer', 'vodka', 'potato'),
 ('chicken', 'pizza', 'burger', 'potato', 'fries', 'mustache'),
 ('chicken', 'pizza', 'burger', 'vodka', 'fries', 'mustache'),
 ('chicken', 'pizza', 'burger', 'vodka', 'potato', 'fries'),
 ('chicken', 'pizza', 'burger', 'vodka', 'potato', 'mustache'),
 ('chicken', 'pizza', 'vodka', 'potato', 'fries', 'mustache'),
 ('pizza', 'beer', 'vodka', 'potato', 'fries', 'mustache'),
 ('pizza', 'burger', 'beer', 'potato', 'fries', 'mustache'),
 ('pizza', 'burger', 'beer', 'vodka', 'fries', 'mustache'),
 ('pizza', 'burger', 'beer', 'vodka', 'potato', 'fries'),
 ('pizza', 'burger', 'beer', 'vodka', 'potato', 'mustache'),
 ('pizza', 'burger', 'vodka', 'potato', 'fries', 'mustache')}

Upvotes: 0

spicavigo
spicavigo

Reputation: 4224

Perhaps this would help

def get_set(li, phrase_len):
    l = len(li)
    for i in range(l):
        if phrase_len <= l-i:
            yield(li[i:i+phrase_len])

a_list=['chicken','pizza','burger','beer','vodka','potato','fries','mustache']
print list(get_set(a_list, 6))

Run the code here http://codebunk.com/bunk#-IsxjI9Up1AgOfi0nuCd

Upvotes: 1

Martijn Pieters
Martijn Pieters

Reputation: 1122032

You are looking for a sliding window generator instead:

from itertools import islice

def window(seq, n=2):
    "Returns a sliding window (of width n) over data from the iterable"
    "   s -> (s0,s1,...s[n-1]), (s1,s2,...,sn), ...                   "
    it = iter(seq)
    result = tuple(islice(it, n))
    if len(result) == n:
        yield result    
    for elem in it:
        result = result[1:] + (elem,)
        yield result

list(window(a_list, 6))

which gives:

>>> list(window(a_list, 6)) 
[('chicken', 'pizza', 'burger', 'beer', 'vodka', 'potato'), ('pizza', 'burger', 'beer', 'vodka', 'potato', 'fries'), ('burger', 'beer', 'vodka', 'potato', 'fries', 'mustache')]

You are not creating python sets here, you need to be careful with your terminology.

Specifically, you are not testing when the second index reaches the end of the list:

a_windows = []
index1 = 0
index2 = 6

while index2 <= len(a_list):
    a_windows.append(a_list[index1:index2])
    index1 += 1
    index2 += 1

which works:

>>> a_windows
[['chicken', 'pizza', 'burger', 'beer', 'vodka', 'potato'], ['pizza', 'burger', 'beer', 'vodka', 'potato', 'fries'], ['burger', 'beer', 'vodka', 'potato', 'fries', 'mustache']]

Upvotes: 2

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