CODEWITHSUNDEEP
python-3.xstringstartswith
coredumped0x
coredumped0x

Reputation: 848

Check if a string startswith any element in a tuple, if True, return that element

I have a tuple of values as follows:

commands = ("time", "weather", "note")

I get an input from the user and I check if the input matches any value in the tuple as follows:

if user_input.startswith(commands):
    # Do stuff based on the command

What I would like to do is exactly as the above, but with the matched item returned. I tried many methods, but nothing really worked. Thank you in advance.

Edit: At some point I thought I could use the Walrus operator, but you would figure out it wouldn't work.

if user_input.startswith(returned_command := commands):
    command = returned_command
    # actually command only gets the commands variable.

Upvotes: 0

Views: 565

Answers (4)

DaBrain
DaBrain

Reputation: 3185

With Python 3.8 or later this should work:

if any(user_input.startswith(returned_command := c) for c in commands):
    print(returned_command)

Upvotes: 0

Guimoute
Guimoute

Reputation: 4649

You can use any.

user_input = input()
if any(user_input.startswith(s) for s in commands):
    # The input is valid.

If you want to ask for user inputs until their reply is valid, shove that in a while loop.

match = None

while True:
    user_input = input()
    if any(user_input.startswith(s) for s in commands): # Make sure there is a match at all. 
       for c in commands:
           if user_input.startswith(c):
               match = c # Find which command matched in particular.
               break     # Exit the loop.
    else:
        print(f"Your selection should be one of {commands}.")


# ...
# Do something with the now valid input and matched element.
# ...

Upvotes: 0

Patrick Haugh
Patrick Haugh

Reputation: 61032

This function takes a function of one argument and a list of arguments, and will return the first argument that makes the function return a truthy value. Otherwise, it will raise an error:

def first_matching(matches, candidates):
    try:
        return next(filter(matches, candidates))
    except StopIteration:
        raise ValueError("No matching candidate")

result = first_matching(user_input.startswith, commands)

Upvotes: 1

Errol
Errol

Reputation: 610

Try this. You can store your functions inside a dictionary and call them.

def print_time():
    print("Time")

def exit_now():
    exit()

def print_something(*args):
    for item in args:
        print(item)

command_dict = {
    "time": print_time,
    "something": print_something,
    "exit": exit_now
}

while True:
    user_input = input("Input command: ")
    command, *args = user_input.split()
    command_dict[command](*args)

output:

Input command: time
Time
Input command: something 1 2 3
1
2
3
Input command: exit

Upvotes: 1

Related Questions