python - Function returns only the first element during iteration

Question

this is what I have so far:

def sort_contacts(sort_contacts):
    contacts = sorted(sort_contacts.items())

    for (k, v) in contacts:
        return list([(k,)+ v])

from test import testEqual

testEqual(sort_contacts({"Summitt, Pat":("1-865-355-4320","[email protected]"),
"Rudolph, Wilma": ("1-410-5313-584", "[email protected]")}),
[('Rudolph, Wilma', '1-410-5313-584', '[email protected]'),
('Summitt, Pat', '1-865-355-4320', '[email protected]')])
testEqual(sort_contacts({"Dinesen, Isak": ("1-718-939-2548", "[email protected]")}),
[('Dinesen, Isak', '1-718-939-2548', '[email protected]')])

###############

here is the result

Test Failed: expected [('Rudolph, Wilma', '1-410-5313-584','[email protected]'), ('Summitt, Pat', '1-865-355-4320', '[email protected]')] but got [('Rudolph, Wilma', '1-410-5313-584', '[email protected]')]
    Pass

How can I fix it so that it grabs more than one key and value in the library of contacts

Answer 1

The issue here is the way you return your data. Consider a simple example:

In [263]: def foo(data):
     ...:     for k, v in sorted(data.items()):
     ...:         return [(k, ) + v]
     ...:     

In [264]: foo({'a' : ('b', 'c'), 'd' : ('e', 'f')})
Out[264]: [('a', 'b', 'c')]

What's happening is that the return statement returns the first item back to the caller. Once the function returns, it does not resume execution and return any more items as you might expect. Because of this, you only see one item returned.

There are two possibilities as a solution. You could either return everything in a list, or use the yield syntax.

Option 1
return <list>

In [271]: def foo(data):
     ...:     return[(k,) + v for  k, v in sorted(data.items())]
     ...:         

In [272]: foo({'a' : ('b', 'c'), 'd' : ('e', 'f')})
Out[272]: [('a', 'b', 'c'), ('d', 'e', 'f')]

---

Option 2
yield

In [269]: def foo(data):
     ...:     for k, v in sorted(data.items()):
     ...:         yield (k, ) + v
     ...:     

In [270]: list(foo({'a' : ('b', 'c'), 'd' : ('e', 'f')}))
Out[270]: [('a', 'b', 'c'), ('d', 'e', 'f')]

Note that list(...) is needed around the function call because yield results in a generator being returned, which you must iterate over to get your final list result.