Python Forum - Palindrome in Python

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Hi,
I'm implemented this function to check if a string is palindrome or not.
But when I use a palindrome word such as "radar" for example, my function return False.

def is_polindrome_word(word):
  word_start = ''
  for letter in word:
    word_start = letter + word_start
    if( word == word_start):
     return True


  return False

      
  


test_word= 'radar'
if __name__ == "__main__":

  print(is_polindrome_word(test_word))

How can I do return True my word?
and if there are suggestion to make my code better , I will accepted (an explanation would be welcome ,because I'm beginner Smile

)
Regards,
RavCoder

def is_polindrome_word(word):
    return word==word[::-1]

test_word= 'radar'
print(is_polindrome_word(test_word))

Output:
True

[::-1] allows you to revert a string

(Oct-16-2019, 08:54 AM)baquerik Wrote: [ -> ]
def is_polindrome_word(word):
    return word==word[::-1]

test_word= 'radar'
print(is_polindrome_word(test_word))
Output:
True
[::-1] allows you to revert a string

Thanks, if I didn't want to use slice notation instead?

it works for me when indentation is correct

def is_palindrome(word):
    word_start = ''
    for letter in word:
        word_start = letter + word_start
        if word == word_start:
            return True
 
    return False

for word in ['radar', 'blabla']:
    print(f"{word} ==> {is_palindrome(word)}")

Output:radar ==> True
blabla ==> False

and for improvements, well

def is_palindrome(word):
    return word == word[::-1]

(Oct-16-2019, 09:00 AM)RavCOder Wrote: [ -> ]if I didn't want to use slice notation instead?

Is this a homework> if yes - post your restrictions in advance and in the proper forum section

(Oct-16-2019, 09:03 AM)buran Wrote: [ -> ]it works for me when indentation is correct

def is_palindrome(word):
    word_start = ''
    for letter in word:
        word_start = letter + word_start
        if word == word_start:
            return True
 
    return False

for word in ['radar', 'blabla']:
    print(f"{word} ==> {is_palindrome(word)}")

Output:radar ==> True
blabla ==> False

and for improvements, well

def is_palindrome(word):
    return word == word[::-1]

Thanks, now It works, I didn't see that it wasn't indented correctly because my compiler didn't report identation error.
No, it's not a homework, I'm self-taught Smile

Some things to consider:

- name 'Hannah' should be palindrome but with current code it's not
- palindrome can mean different things for different people. According to wikipedia article:

Quote:A palindrome is a word, number, phrase, or other sequence of characters which reads the same backward as forward, such as taco cat or madam or racecar or the number 10801. Sentence-length palindromes may be written when allowances are made for adjustments to capital letters, punctuation, and word dividers, such as "A man, a plan, a canal, Panama!", "Was it a car or a cat I saw?" or "No 'x' in Nixon".

You can try to write a function which covers all the types of palindromes defined in wikipedia.

(Oct-16-2019, 10:24 AM)perfringo Wrote: [ -> ]Some things to consider:

- name 'Hannah' should be palindrome but with current code it's not
- palindrome can mean different things for different people. According to wikipedia article:

Quote:A palindrome is a word, number, phrase, or other sequence of characters which reads the same backward as forward, such as taco cat or madam or racecar or the number 10801. Sentence-length palindromes may be written when allowances are made for adjustments to capital letters, punctuation, and word dividers, such as "A man, a plan, a canal, Panama!", "Was it a car or a cat I saw?" or "No 'x' in Nixon".

You can try to write a function which covers all the types of palindromes defined in wikipedia.

I didn't understand exactly.
What do you mean with all cases?
And how should I set my conditions for testing?

You could change the code so it ignores symbols and uppercase/lowercase distinctions, so it matches more types of palindromes like:

Hannah
hannah, wow hannah!

(Oct-16-2019, 12:18 PM)RavCOder Wrote: [ -> ]I didn't understand exactly.
What do you mean with all cases?
And how should I set my conditions for testing?

You could extend your function so that it returns True for following strings which can be interpreted as palindromes:

>>> def is_palindrome(word):
...     word_start = ''
...     for letter in word:
...         word_start = letter + word_start
...         if word == word_start:
...             return True
...   
...     return False
... 
>>> is_palindrome('Hannah')
False
>>> is_palindrome('Was it a car or a cat I saw?')
False

One way of doing it is to 'clean string' (convert all lowercase, remove spaces and punctuation) and only after that make the comparison.

Something along those lines:

>>> import string
>>> def is_palindrome(text):
...     cleaned = [letter.lower() for letter in ''.join(text.split()) if letter not in string.punctuation]
...     return all(forward == backward for forward, backward in zip(cleaned, reversed(cleaned))) 
... 
>>> is_palindrome('Was it a car or a cat I saw?')
True
>>> is_palindrome('Hannah')
True
>>> is_palindrome('better')
False

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