python lowercase function for-loop

Question

I am trying to create a function to lower case all inputs.

in the end I should be able to lowercase:

result = lowerList('Jen', 'Suzie')
print(result)

so far I have:

def lowerList(input1, input2):
  myList = [input1, input2]
  for x in myList:
    return(x.lower())

result = lowerlist('Jen', 'Suzie')
print(result)

jen

So right now I am only able to get the first input. Also how can I modify this to loop continuously for any number of inputs without modifying the function?

Answer 1

Your problem is that your returning on the first iteration of your for loop, after you've only operated on one element. You need to build up a list of modified values, then return the whole list.

You could do this manually:

def lower_list(*args):
    strings = []
    for string in args:
        strings.append(string.lower())
    return strings

But a simpler and more elegant solution is to use a list comprehension:

def lower_list(*args):
    return [string.lower() for string in args]

Another option if you perfer it, is to use a generator;

def lower_list(*args):
    for string in args:
        yield string.lower()

And it would be used like so:

>>> str_gen = lower_list('Hello', 'WORld', 'Name', 'BUCKs')
>>> next(str_gen)
'hello'
>>> next(str_gen)
'world'
>>> next(str_gen)
'name'
>>> # etc...

Or if you need the entire list of strings at once:

>>> list(lower_list('Hello', 'WORld', 'Name', 'BUCKs'))
['hello', 'world', 'name', 'bucks']

Answer 2

def to_lower(*args):                      
    return [arg.lower() for arg in args]  

>>> to_lower('SPAM', 'Eggs')
['spam', 'eggs']           

Answer 3

You do not return in loop which aborts the for loop right there. Instead create a new list append the lowered elements to it inside the for loop amd return once the loop is done.

Answer 4

That's because when you return the for loop stops. What you should do is append the result string to a list and return it. Using your code as base:

def lowerList(input1, input2):
  myList = [input1, input2]
  l = []
  for x in myList:
    l.append(x.lower())
  return l

result = lowerList('Jen', 'Suzie')
print(result)

Answer 5

Depending on how big your lists are going to get, it may even be more efficient to use generators:

def to_lower(*args):                      
    for arg in args:
        yield arg.lower()  

Answer 6

The reason you are only getting the first input is because you are only returning the first input. After you return from a function, you cannot get back inside that function unless you call it again.

for x in myList: return(x.lower())

Instead, you can do something like this:

def lowerList(myList):
  normalList = []
  for x in myList:
    normalList.append(x.lower())
  return normalList

normalList = ['Jen', 'Suzie']
result = lowerList(normalList)
print(result)

Return a new list where all the items are lowercased, and print that.

Hope this helps!