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Adrian Vraciu
Adrian Vraciu

Reputation: 45

Python: issue in adding elements to a list

I have a small problem in adding the results printed by a function to a list. The situation is like this. The function prints some results like this

result1
result2
result3

How do I add them into a list, to see them like mylist=['result1', 'result2', 'result3']? Because, in my case, I am working with a for loop which calculates every case using the function written by me (and prints the results like above) but using append function, it prints something like this:

 ['result1'], ['result1', 'result2'], ['result1', 'result2', 'result3'].

Of course, using the last result, ['result1', 'result2', 'result3'], should be perfect for me, but I am getting three lists like above. What ca I do to have only the last list, the one with those three results?

Ok guys, I'm gonna put some code here to be more specific. I have a large string (and I'm not gonna write it here because is not so important). My function is splitting from that string some specific url's. The function is this:

def fileref(string, file):
    start=string.find(file) + 28
    end=string.find('</ref', start)
    file=string[start:end]
    return file

I have this list with arguments for the function:

files55_2=['f55_1.jpg', 'f55_2.jpg', 'f55_3.txt', 'f55_4.mp4']

Then, with a for loop I do this:

for i in files55_2:
    print fileref(string, i)

which prints me these urls:

https://myapi.net/file1
https://myapi.net/file2
https://myapi.net/file3
https://myapi.net/file4

Now I need a solution to have a list with all these elements, like this:

mylist=['https://myapi.net/file1', 'https://myapi.net/file2', 'https://myapi.net/file3', 'https://myapi.net/file4']

I hope I am more specific now. Thanks anyway for your answers!

Upvotes: 0

Views: 198

Answers (3)

BioGeek
BioGeek

Reputation: 22827

In your function you are incrementally building your list and printing out the list after every step, something like this:

l = []
for i in range(1,4):
    l.append("result {0}".format(i))
    print l

output:

['result 1']
['result 1', 'result 2']
['result 1', 'result 2', 'result 3']

What you want to do is to print out the list after you are done creating it, something like:

l = []
for i in range(1,4):
    l.append("result {0}".format(i))
print l

output:

['result 1', 'result 2', 'result 3']

edit: In the provided code, change these lines:

for i in files55_2:
    print fileref(string, i)

to:

mylist = []
for i in files55_2:
    mylist.append(fileref(string, i))
print mylist

Upvotes: 5

James Robinson
James Robinson

Reputation: 822

You might be better off having your function append the results to the list, then printing outside the function. 

>>> def append():
...   l = []
...   for i in range(3):
...     l.append(str(i))
...   return l
...
>>> l = append()
>>> l
['0', '1', '2']

Or if you already have the list before running the function, you won't need to return it.

>>> def append(l):
...   for i in range(3):
...     l.append(str(i))
...
>>> l = []
>>> append(l)
>>> l
['0', '1', '2']

Upvotes: 2

Kzhi
Kzhi

Reputation: 430

In for loop you can use "else" close, which executes after loop has finished:

for ...
   ...
else
   //here you can add your results to list after loop has finished

Upvotes: 1

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