How can I use startswith without specifying a certain string? Is there any alternative?

Question

I would like to apply vocal_start to so many different variables and i can’t handle them all and i wouldn’t always repeat startswith. So I don’t want to write variable1.startswith(("a", "e", "i", "o", "u")), but i would like to apply startswith(("a", "e", "i", " o", "u")) directly to all variables without specifying variable1.startswith (something similar to my code). I wouldn’t always repeat startswith

I guess using startswith is only like this (variable1.startswith), so is there anything else I can use? I need something like my code, but not with startswith (or I’d like to use startswith differently if possible)

vocal_start = startswith(("a", "e", "i", "o", "u"))

variable1 = "open"

#Only for Test
if variable1 == vocal_start:
    print("correct")

In the code, of course, I get the NameError: name 'startswith' is not defined because I didn’t specify variable1.startswith(("a", "e", "i", "o", "u")), but as I said, I don’t want to go this route

Asked By: Evangelos Dellas

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Answer 1

If the values to check are all 1 character (or all the same length) you could use the in operator with a substring to get the first letter(s):

if variable[:1] in ("a", "e", "i", "o", "u"):
   ...

or

if variable[:1] in "aeiou":
   ...

Answered By: Alain T.

Answer 2

You can write a function that checks if the string provided starts with a vowel:

def starts_with_vowel(str):
    return str.lower().startswith(("a", "e", "i", "o", "u")) # lower to be more general

variable1 = "open"

# check if it starts with a vowel
if starts_with_vowel(variable1):
    print("correct")

Answered By: Marcelo Paco

Answer 3

You can get your desired form to work if you don’t mind writing really obscure code. Write a class whose __eq__ does what you want and then use an instance of that class for your compare.

>>> class Startswith:
...     def __eq__(self, rhs):
...             return rhs.startswith(('a', 'e', 'i', 'o', 'u'))
... 
>>> startswith = Startswith()
>>> "abcd" == startswith
True
>>> "xxx" == startswith
False

Answered By: tdelaney

Answer 4

It’s silly, but you can use operator.methodcaller to make a function that, called on any variable, will invoke the named method with the provided arguments, e.g.:

from operator import methodcaller  # At top of file

starts_with_vowel = methodcaller('startswith', ('a', 'e', 'i', 'o', 'u'))  # Done once at top level

# Done whenever you need to test a given variable
if starts_with_vowel(any_variable_producing_a_string):
    ...

To be clear, there’s no reason to do this. It’s just needlessly splitting up simple parts of program logic across your code rather than keeping it close together. In real code, I’d just do:

if variable.startswith(('a', 'e', 'i', 'o', 'u')):

or if the set of prefixes to use is used in multiple places and long enough to be worth factoring out:

vowels = ('a', 'e', 'i', 'o', 'u')  # Done once at top level

# Done each place that needs the test
if variable.startswith(vowels):
    ...

Answered By: ShadowRanger

Answer 5

def vowelstart(s):
    
    if(s[0].lower() in ("a", "e", "i", "o", "u")):
    
        return True
    
    return False

#Edited

Answered By: Magaren

Answer 6

How about using regex instead of startswith()? A regular expression implementation could look like this:

import re

variable1 = "open"

if re.match(r"^[aeiou]", variable1):
  print("correct")

Explanation of r"^[aeiou]":

r" ... " is a raw string often used for regex patterns.
^ simply means starts with.
[aeiou] is a set of allowed characters.

I would probably wrap the regex in a function to make it more readable and pythonic. And compiling the pattern once outside the function may improve performance if the function is used often:

import re

STARTS_WITH_VOWEL_PATTERN = re.compile(r"^[aeiou]", re.IGNORECASE)

def starts_with_vowel(text: str) -> bool:
  return True if STARTS_WITH_VOWEL_PATTERN.match(text) else False

if starts_with_vowel("open"):
  print("correct")

I hope this is helpful.

Answered By: Jakob Bagterp

How can I use startswith without specifying a certain string? Is there any alternative?

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