Learn Python : Shift Letters – ascii, index (Mid)

Question:

Given a string, you need to return a new string where every letter is shifted to its right by one place in alphabetical order. The last letters z and Z should be replaced with the first ones: a and A, respectively. If the character isn't a letter, it should stay the same.

For example, given the string "abc123XYz!", the function should return "bcd123YZa!".

Method 1: Using a List of Characters

Python

def shift_letters_list(text):
  """Shifts each letter in a string to the right by one place.

  Args:
    text: The input string.

  Returns:
    A new string with shifted letters.
  """

  # Create a list to store the characters of the input string
  char_list = list(text)

  # Iterate over each character in the list
  for i in range(len(char_list)):
    char = char_list[i]

    # Check if the character is a lowercase letter
    if char.islower():
      # Shift the letter to the right, wrapping around from 'z' to 'a'
      if char == 'z':
        char_list[i] = 'a'
      else:
        char_list[i] = chr(ord(char) + 1)

    # Check if the character is an uppercase letter
    elif char.isupper():
      # Shift the letter to the right, wrapping around from 'Z' to 'A'
      if char == 'Z':
        char_list[i] = 'A'
      else:
        char_list[i] = chr(ord(char) + 1)

  # Join the characters in the list back into a string
  shifted_text = ''.join(char_list)
  return shifted_text

# Example usage
text = "abc123XYz!"
shifted_text = shift_letters_list(text)
print(shifted_text)  # Output: bcd123YZa!

Explanation:

  1. Create a list of characters: We convert the input string into a list of characters, making it easier to modify each character individually.
  2. Iterate over each character: We loop through each character in the list.
  3. Check for lowercase letters: If the character is a lowercase letter, we check if it's 'z'. If it is, we replace it with 'a'. Otherwise, we increment its ASCII code by 1 to get the next letter.
  4. Check for uppercase letters: We do a similar check for uppercase letters, wrapping around from 'Z' to 'A'.
  5. Join the characters: After modifying all characters, we join the list back into a string.

Method 2: Using a Loop and String Concatenation

Python

def shift_letters_loop(text):
 """Shifts each letter in a string to the right by one place. 
 Args: text: The input string. 
 Returns: A new string with shifted letters. """
 shifted_text = "" # Initialize an empty string to store the result
 for char in text: if char.islower(): if char == 'z': shifted_text += 'a'
 else: shifted_text += chr(ord(char) + 1) elif char.isupper(): if char == 'Z': shifted_text += 'A'
 else: shifted_text += chr(ord(char) + 1) else: shifted_text += char 
 return shifted_text 
# Example usage
text = "abc123XYz!"
shifted_text = shift_letters_loop(text) print(shifted_text) # Output: bcd123YZa!

Use code with caution.

Explanation:

  1. Initialize an empty string: We create an empty string to store the shifted characters.
  2. Iterate over each character: We loop through each character in the input string.
  3. Check and shift characters: Similar to the previous method, we check if the character is a letter, and if so, we shift it accordingly.
  4. Concatenate characters: We add the shifted character or the original character (if it's not a letter) to the shifted_text string.
  5. Return the shifted string: After processing all characters, we return the final shifted_text.

Claude

Given a string, you need to return a new string where every letter is shifted to its right by one place in alphabetical order. The last letters z and Z should be replaced with the first ones: a and A, respectively. If the character isn't a letter, it should stay the same.

Here are two different methods to solve this problem:

Method 1: Using ASCII values

pythondef shift_letters(input_string):
 """
 Shift each letter in the string by one place in the alphabet.
 Replace 'z' and 'Z' with 'a' and 'A' respectively.
 Non-letter characters remain the same.
 """
 output_string = ''
 for char in input_string:
 # Check if the character is a letter
 if char.isalpha():
 # Get the ASCII value of the character
 ascii_value = ord(char)
 
 # Shift the letter by one place in the alphabet
 if char.islower():
 new_ascii_value = (ascii_value - 97 + 1) % 26 + 97
 else:
 new_ascii_value = (ascii_value - 65 + 1) % 26 + 65
 
 # Replace 'z' and 'Z' with 'a' and 'A'
 if new_ascii_value == 97 or new_ascii_value == 65:
 new_ascii_value -= 1
 
 # Convert the ASCII value back to a character
 new_char = chr(new_ascii_value)
 output_string += new_char
 else:
 # Non-letter characters remain the same
 output_string += char
 
 return output_string

This method uses the ord() function to get the ASCII value of each character, then shifts the value by one place in the alphabet. It also handles the special case of 'z' and 'Z' by replacing them with 'a' and 'A' respectively.

Method 2: Using a lookup table

pythondef shift_letters(input_string):
 """
 Shift each letter in the string by one place in the alphabet.
 Replace 'z' and 'Z' with 'a' and 'A' respectively.
 Non-letter characters remain the same.
 """
 # Create a lookup table for shifting letters
 lookup_table = {
 'a': 'b', 'b': 'c', 'c': 'd', 'd': 'e', 'e': 'f', 'f': 'g', 'g': 'h',
 'h': 'i', 'i': 'j', 'j': 'k', 'k': 'l', 'l': 'm', 'm': 'n', 'n': 'o',
 'o': 'p', 'p': 'q', 'q': 'r', 'r': 's', 's': 't', 't': 'u', 'u': 'v',
 'v': 'w', 'w': 'x', 'x': 'y', 'y': 'z', 'z': 'a',
 'A': 'B', 'B': 'C', 'C': 'D', 'D': 'E', 'E': 'F', 'F': 'G', 'G': 'H',
 'H': 'I', 'I': 'J', 'J': 'K', 'K': 'L', 'L': 'M', 'M': 'N', 'N': 'O',
 'O': 'P', 'P': 'Q', 'Q': 'R', 'R': 'S', 'S': 'T', 'T': 'U', 'U': 'V',
 'V': 'W', 'W': 'X', 'X': 'Y', 'Y': 'Z', 'Z': 'A'
 }
 
 output_string = ''
 for char in input_string:
 # Check if the character is a letter
 if char.isalpha():
 # Shift the letter using the lookup table
 output_string += lookup_table.get(char, char)
 else:
 # Non-letter characters remain the same
 output_string += char
 
 return output_string

This method uses a lookup table to map each letter to its shifted counterpart. It checks if the character is a letter, and if so, looks up the new character in the table. If the character is not a letter, it remains the same.

Both methods will take an input string, shift each letter by one place in the alphabet, and replace 'z' and 'Z' with 'a' and 'A' respectively. Non-letter characters will remain unchanged.

For example, if the input string is "abc123XYz!", the output will be "bcd123YZa!" for both methods.

def shift_letters_using_ascii(s): # This will store our resulting new string shifted_string = "" # Loop through each character in the input string for char in s: # Get the ASCII value of the character using ord() ascii_value = ord(char) # Check if it's a lowercase letter (from 'a' to 'z') if 97 <= ascii_value <= 122: # ASCII range for 'a' (97) to 'z' (122) # If it's 'z', shift to 'a'. Otherwise, just shift to the next letter. if ascii_value == 122: shifted_string += chr(97) # 'a' has ASCII value of 97 else: shifted_string += chr(ascii_value + 1) # Check if it's an uppercase letter (from 'A' to 'Z') elif 65 <= ascii_value <= 90: # ASCII range for 'A' (65) to 'Z' (90) # If it's 'Z', shift to 'A'. Otherwise, just shift to the next letter. if ascii_value == 90: shifted_string += chr(65) # 'A' has ASCII value of 65 else: shifted_string += chr(ascii_value + 1) # If it's not a letter, just add the character as it is else: shifted_string += char return shifted_string# Test the function with the exampleinput_string = "abc123XYz!"result = shift_letters_using_ascii(input_string)print("Original String:", input_string)print("Shifted String:", result)

def shift_letters_using_ascii(s):
    # This will store our resulting new string
    shifted_string = ""

    # Loop through each character in the input string
    for char in s:
        # Get the ASCII value of the character using ord()
        ascii_value = ord(char)

        # Check if it's a lowercase letter (from 'a' to 'z')
        if 97 <= ascii_value <= 122:  # ASCII range for 'a' (97) to 'z' (122)
            # If it's 'z', shift to 'a'. Otherwise, just shift to the next letter.
            if ascii_value == 122:
                shifted_string += chr(97)  # 'a' has ASCII value of 97
            else:
                shifted_string += chr(ascii_value + 1)

        # Check if it's an uppercase letter (from 'A' to 'Z')
        elif 65 <= ascii_value <= 90:  # ASCII range for 'A' (65) to 'Z' (90)
            # If it's 'Z', shift to 'A'. Otherwise, just shift to the next letter.
            if ascii_value == 90:
                shifted_string += chr(65)  # 'A' has ASCII value of 65
            else:
                shifted_string += chr(ascii_value + 1)

        # If it's not a letter, just add the character as it is
        else:
            shifted_string += char

    return shifted_string


# Test the function with the example
input_string = "abc123XYz!"
result = shift_letters_using_ascii(input_string)
print("Original String:", input_string)
print("Shifted String:", result)

x, y = 7, 5
if x > y: print('x is greater') 
# Prints x is greater

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