[1115] Python re library examples

Ref: Python RegEx

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To find a pattern like "Page " followed by a number in a string, you can use the `re` (regular expressions) module in Python. Here's how you can do it:

1. Import the re module:

   import re
   

2. Define your string:

   text = "This is a sample text with Page 1, Page 23, and Page 456."
   

3. Use a regular expression to find the pattern:

   # Define the pattern
   pattern = r"Page \d+"
   
   # Find all matches
   matches = re.findall(pattern, text)
   
   # Print the matches
   print(matches)
   

Explanation:

• import re: Imports the re module for working with regular expressions.
• pattern = r"Page \d+": Defines the pattern to search for. Page matches the literal text "Page ", and \d+ matches one or more digits.
• re.findall(pattern, text): Finds all occurrences of the pattern in the string.
• print(matches): Prints the list of matches.

Example:

Here's a complete example:

import re

# Define your string
text = "This is a sample text with Page 1, Page 23, and Page 456."

# Define the pattern
pattern = r"Page \d+"

# Find all matches
matches = re.findall(pattern, text)

# Print the matches
print(matches)

Output:

Running this script will produce the following output:

['Page 1', 'Page 23', 'Page 456']

This will give you a list of all occurrences of "Page " followed by a number in the string.

If you need any further assistance or have more questions, just let me know! 😊

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To get the index of the first match for a pattern in a string using the re module in Python, you can use the re.search() function. Here's how you can do it:

1. Import the re module:

   import re
   

2. Define your string:

   text = "This is a sample text with Page 1, Page 23, and Page 456."
   

3. Use a regular expression to find the pattern and get the index:

   # Define the pattern
   pattern = r"Page \d+"
   
   # Search for the pattern in the text
   match = re.search(pattern, text)
   
   # Check if a match is found
   if match:
       # Get the index of the first match
       index = match.start()
       print(f"First match found at index {index}")
   else:
       print("No match found")
   

Explanation:

• import re: Imports the re module for working with regular expressions.
• pattern = r"Page \d+": Defines the pattern to search for. Page matches the literal text "Page ", and \d+ matches one or more digits.
• re.search(pattern, text): Searches for the pattern in the text. It returns a match object if the pattern is found; otherwise, it returns None.
• match.start(): Returns the starting index of the match.

Example:

Here's a complete example:

import re

# Define your string
text = "This is a sample text with Page 1, Page 23, and Page 456."

# Define the pattern
pattern = r"Page \d+"

# Search for the pattern in the text
match = re.search(pattern, text)

# Check if a match is found
if match:
    # Get the index of the first match
    index = match.start()
    print(f"First match found at index {index}")
else:
    print("No match found")

Output:

Running this script will produce the following output:

First match found at index 26

This will give you the index of the first occurrence of "Page " followed by a number in the string.

If you need any further assistance or have more questions, just let me know! 😊