CODEWITHSUNDEEP
python-2.7
lostprophet
lostprophet

Reputation: 15

Getting only one answer from a list python

I may have a noob question, but here it goes. I need to parse through a list and I need the return to be specific. Here is the code:

a = 11
bla = [1,2,3,4,5,6,7,8,9,10]

lista = []
for element in bla:
    if element == a:
        lista.append(element)
    else:
        lista.append('not found')
print lista

This way - the return is 10 times - 'not found' - and I need it only one time. lista = ['not found'] Any ideas?

Upvotes: 0

Views: 152

Answers (1)

Primusa
Primusa

Reputation: 13498

Use python's built in lst.count()

a = 11
bla = [1,2,3,4,5,6,7,8,9,10]

# get number of times a occurs in bla
cnt = bla.count(a)

# if cnt isn't zero then lista becomes a repeated cnt times, otherwise just not found
lista = [a] * cnt if cnt >= 1 else ["not found"]

print(lista)
>>>["not found"]

Edit:

Jean-François Fabre suggested are more pythonic version for building lista:

lista = [a] * cnt or ["not found"]

Edit 2:

If you want to do something similar for dictionaries you only have to implement the count function for yourself. I turned user into a string literal since making it a list and doing user[0] each time is pointless:

user = 'john'
user_details = [{u'UserName': u'fred', u'LastSeen': u'a'}, {u'UserName': u'freddy', u'LastSeen': u'b'}]

# get the count
cnt = sum(i['UserName'] == user for i in user_details)

#do what we did before
lista = [user] * cnt or ["not found"]

Edit 3:

Finally if you want to use a for loop, check if it's not found at the end instead of at each step:

user = ['john']

user_details = [{u'UserName': u'fred', u'LastSeen': u'a'},{u'UserName': u'freddy', u'LastSeen': u'b'}]
lis = []
for element in user_details:
    if element['UserName'] == user[0]:
        lis.append(element)
if not lis: lis.append("not found")

Upvotes: 0

Related Questions