How do i print a list of names (from user input) in the format of "First Initial. Last Name"? (python 3)

Try this.

lst = ['Tony Stark', 'Steve Rodgers', 'Wade Wilson']

def f(s): # if s='Tony Stark'
    s = s.split(' ') #
    return s[0][0]+'. ' + ' '.join(s[1:]) # s[0][0] is T and then I add '. ' to 'T' and then I convert the rest of the word list to string using the join function an add it to the string.
outLst = map(f,lst)

print(*outLst,sep='n')

Output

T. Stark
S. Rodgers
W. Wilson

1. First I use the map function to iterate through all elements and execute a function f for all element one by one. (You can also use list comprehension).
2. In the f function I convert the string to a list using the split function.
3. Then I return the modified string.

You can do something like this,

In [32]: l = ['Tony Stark', ' Steve Rodgers', ' Wade Wilson']

In [33]: [f'{i.split()[0][0]}.{i.split()[1]}' for i in l]
Out[33]: ['T.Stark', 'S.Rodgers', 'W.Wilson']

The question says "Enter list of names" which I take to be a comma delimited single string of input. If that’s the case then:

list_of_names = 'Tony Stark, Steve Rodgers, Wade Wilson'

for forename, surname in map(str.split, list_of_names.split(',')):
    print(f'{forename[0]}. {surname}')

Output:

T. Stark
S. Rodgers
W. Wilson

Ok, so firstly you need to call a built-in (native to the Python language) input function, which will open a text input stream for you and you will be able to provide some data to the program via console and/or terminal. You can read about built-in functions and input function specifically here and here. The code you need to start with in order to open mentioned stream can look as follows:

names = input('Type names separated by commas (e.g. Tony Stark, Thor Odinson): ')

When you will run your program, you will see in the console:

Type names separated by commas (e.g. Tony Stark, Thor Odinson): 

Now you can provide the names you want to provide after the colon, e.g. Tony Stark, Thor Odinson and hit enter/return keyboard key when you’re done in order to close the input stream. After this operation, the data you’ve provided will be represented as a sequence/string of characters of a built-in data type called str, which is an abbreviation from string (native to Python language). For more information about built-in data types in Python language see this page. Nevertheless, you can check your data by typing:

print(names, type(names))

…which will give you an output:

Tony Stark, Thor Odinson <class 'str'>

Finally, in order to transform provided data in a way you want it to be transformed we need to cut it and organize in a specific way. First look at the code and later at the description of it below:

names = names.replace(', ', ',').split(',')
for name in names:
    first, last = name.split(' ')
    print(f'{first[0]}. {last}')

At the first line we replace commas followed by whitespaces to commas, and split the resulting sequence by commas, so we will get a list consisting of two elements:

['Tony Stark', 'Thor Odinson']

Now, what we need to do, is to iterate over the elements of the list, e.g. with the use of the for loop. Finally, we use a split method one more time to cut individual list elements into a first and last name, and we use f-String formatting to build output you wanted to achieve at the first place. You can read about f-String here. Hope this helps.

lst_name = input("Enter a list of names: ")
#separete them in a list
lst = lst_name.split(",")

#get through each name
for names in lst:
     #strip from whitespaces front and end, then split in firstname and lastname
     f, l = names.strip().split(" ")
     #print result
     print(f"{f[0]}. {l}")

If your name contains more than two words, the following solution will help you to create initials for the first names and will display the last name as it is.

names_str = input("Please enter names separated by commas: ")
# names_str = 'Tony Stark, Steve Rodgers, Wade Wilson, James Earl Jones'

for name in names_str.split(','):  # taking names one by one splitting by ','
    first_names, last_name = name.strip().rsplit(' ', 1)  # trim the name and split first names and last name
    initials = '. '.join(first_name[0] for first_name in first_names.split(" "))  # setup initials of the first names
    name_with_initials = f'{initials}. {last_name}'  # concatenate initials with last name
    print(name_with_initials)

Output:

T. Stark
S. Rodgers
W. Wilson
J. E. Jones