Regex clear solution for Morse Decoder by StefanPochmann - python coding challenges

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Regex solution in Clear category for Morse Decoder by StefanPochmann

import re

morse = {'.-': 'A', '-...': 'B', '-.-.': 'C', '-..': 'D', '.': 'E', '..-.': 'F', '--.': 'G', '....': 'H',
         '..': 'I', '.---': 'J', '-.-': 'K', '.-..': 'L', '--': 'M', '-.': 'N', '---': 'O', '.--.': 'P',
         '--.-': 'Q', '.-.': 'R', '...': 'S', '-': 'T', '..-': 'U', '...-': 'V', '.--': 'W', '-..-': 'X',
         '-.--': 'Y', '--..': 'Z', '-----': '0', '.----': '1', '..---': '2', '...--': '3', '....-': '4',
         '.....': '5', '-....': '6', '--...': '7', '---..': '8', '----.': '9'}

def morse_decoder(code):
    return re.sub(' ?(\S+) ?', lambda m: morse[m.group(1)], code).capitalize()

April 6, 2018

Comments:

roncitrus on Feb. 28, 2019, 12:06 p.m.
sweet!

kozhin.asan on Oct. 17, 2020, 4:29 a.m.
What is the meaning of lambda function with `morse[m.group(1)]`?

seed5 on April 16, 2021, 11:16 p.m.
If I understand the code correctly, the first part of re.sub() function, ' ?(\S+) ?', looks for a substring that consists of "0 or 1 space + any non-whitespace characters + 0 or 1 space" -- i.e., a pattern for a morse-coded letter. Second part, morse[m.group(1)], looks up that code in morse code dictionary and substitutes/ replaces it with an actual letter. We need m.group(1) because if we didn't use the group, then instead of looking for an actual pattern as a string, we would look up a regex object, which, obviously, we wouldn't be able to match with any letter in the dictionary.

perimeter on Oct. 23, 2021, 11:28 a.m.
From the documentation: re.sub(pattern, repl, string, count=0, flags=0) If repl is a function, it is called for every non-overlapping occurrence of pattern. The function takes a single match object argument, and returns the replacement string.

myusercb on April 9, 2021, 5:22 p.m.
great solution

cerankas on Oct. 15, 2023, 8:38 a.m.
Very clear solution. I like the simplicity and the way spaces are handled.

Strings Theory

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