Daily Challenge #47 - Alphabets

In today's challenge, you are asked to replace every letter with its position in the alphabet for a given string where 'a' = 1, 'b'= 2, etc.

For example:

alphabet_position("The sunset sets at twelve o' clock.") should return 20 8 5 19 21 14 19 5 20 19 5 20 19 1 20 20 23 5 12 22 5 15 3 12 15 3 11 as a string.

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This challenge comes from MysteriousMagenta on CodeWars. Thank you to CodeWars, who has licensed redistribution of this challenge under the 2-Clause BSD License!

Comments

[Mat-R-Such]

Python

import string
def alphabet_position(text):
    text = [i for i in text.replace(' ','').lower() if i.isalpha() ]
    position = [str(string.ascii_lowercase.find(i)+1) for i in text ]
    return ' '.join(position)

[peter279k]

Here is the simple solution with PHP:

function alphabet_position(string $s): string {
    $s = strtoupper($s);
    $alphabetNums = range(65, 90);
    $alphabets = [];

    foreach ($alphabetNums as $chr) {
        $aphabets[] = chr($chr);
    }

    $result = "";

    $index = 0;
    for (; $index < strlen($s); $index++) {
        if (in_array($s[$index], $aphabets) === false) {
            continue;
        }

        $result .= (string)(ord($s[$index]) - 64) . " ";
    }

    return substr($result, 0, -1);
}

[Héctor Pascual]

Python :

lambda s : ' '.join([str(ord(c)-ord('a')+1) for c in s.lower() if re.search('[a-z]',c)])

[Dev Prakash]

[gist.github.com/devparkk/d46fd8763...]

[sonugan]

C#

public static string AlphabetPosition(string text)
{
   return string.Join(" ", text
    .ToLower()
    .Where(c => char.IsLetter(c))
    .Select(c => (c - 'a') + 1)
    .ToList());
}

[b2aff6009]

A tiny python solutiuon:

def alphabet_position(text):
    converted = [str(ord(c) - ord('a') + 1) for c in text.lower() if c >= 'a']
    return " ".join(converted)

[Ilyes Chouia]

a bit late but here's the answer anyway... in PHP

function alphabet_position($text){
    $alphabet = range('a', 'z');     
    $strippedText = str_split(strtolower(preg_replace("/[^a-zA-Z]/", "", $text)));   
    $result = "";
    foreach($strippedText as $letter){
        $result .= array_search($letter, $alphabet)+1 . " ";   
    }
    return $result;
}
echo alphabet_position("The sunset sets at twelve o' clock.");

[Sven Kanoldt]

solved in rust made with tests first :)

pub fn alphabet_position(s: &str) -> String {
  s.to_lowercase()
    .chars()
    .filter(|x| x.is_alphabetic())
    .map(|x| -> u8 { x as u8 - 'a' as u8 + 1 })
    .map(|x| -> String { x.to_string() })
    .collect::<Vec<String>>()
    .join(" ")
}

#[cfg(test)]
mod test {
  use super::*;

  #[test]
  fn it_should_relace_the_a_with_1() {
    let replaced = alphabet_position("a");
    assert_eq!(replaced, "1");
  }

  #[test]
  fn it_should_relace_the_capital_a_with_1() {
    let replaced = alphabet_position("A");
    assert_eq!(replaced, "1");
  }

  #[test]
  fn it_should_ignore_non_characters() {
    let replaced = alphabet_position("'a a. 2");
    assert_eq!(replaced, "1 1");
  }

  #[test]
  fn it_should_relace_the_sentence() {
    let replaced = alphabet_position("The sunset sets at twelve o' clock.");
    assert_eq!(
      replaced,
      "20 8 5 19 21 14 19 5 20 19 5 20 19 1 20 20 23 5 12 22 5 15 3 12 15 3 11"
    );
  }
}

[Alfredo Salzillo]

One line Javascript

const alphaPosition = str => [...str]
  .filter(letter => /[a-zA-Z]/.test(letter))
  .map(letter => letter.toLowerCase().charCodeAt(0) - 96)
  .join(' ')

[Avalander]

Haskell

Some function composition sorcery in Haskell.

import Data.Char (isLetter, toUpper, ord)

alphabet_position :: String -> String
alphabet_position = unwords . map (show . (flip (-)) 64 . ord . toUpper) . filter isLetter

Explanation

The . operator composes functions, so they will be applied from right to left.

1. filter isLetter will remove all characters that are not letters from the string.
2. map (show . (flip (-)) 64 . ord . toUpper) Transforms each character to its position in the alphabet.
   1. toUpper transforms the character to uppercase, so that we can substract 64 from it's code to know the position.
   2. ord maps a character to its ASCII code.
   3. (flip (-) 64) subtracts 64 from the character code. Since the code for 'A' is 65, this will give us the position in the alphabet starting at index 1. The way it works is it partially applies the second argument of the subtract operator to 64, i.e., this is equivalent to (\x -> x - 64) but fancier.
   4. show maps any type deriving from Show (Int in this case) to String.
3. unwords joins a list of strings using space as a separator.