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How to use search function in python regex.

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by l.rohitharohitha2001@gmail.com dot icon Updated: Dec 6, 2023

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Regular expressions are a useful tool for matching patterns in strings. The re-module provides support for regular expressions.


Regular expressions are a concise and flexible means for matching strings of text. It is such as particular characters, words, or patterns of characters.  

  

Key Concepts of Python Regex:  

1.Pattern: A regular expression pattern is a text string describing a search pattern. It can include literal characters, metacharacters, and various special sequences.  

2.Metacharacters: These are characters with a special meaning. Some common metacharacters.  

  • . (dot): Matches any character except a newline.  
  • ^: Anchors the regex at the start of the string.  
  • $: Anchors the regex at the end of the string.  
  • *: Represents 0 or more occurrences of previous character. 
  • +: Denotes 1 or more occurrences of the previous character. 
  • ?: Represents 0 or 1 occurrence of the preceding character. 
  • \: Escapes a metacharacter, allowing you to match it as a literal.  

3.Character Classes: Character classes allow you to match any one of a set of characters.   

  •  example, [aeiou] matches any vowel.  

4.Quantifiers: Quantifiers specify the number of occurrences of a character or group.   

  • Examples include * (0 or more), + (1 or more), and {n} (exactly n).  

5.Groups and Capturing: Parentheses () creates groups. They can also capture portions of the matched text.   

  • For example, (ab)+ would match "ab," "abab," etc., and (a)(b) would capture "a" and "b" separately.  

6.Special Sequences: These are backslash-escaped sequences that have a special meaning.   

  • For example, \d matches any digit, \w matches any alphanumeric character, and \s matches.  

  

In summary, regex is a fundamental tool for text processing and manipulation. It offers developers a concise and powerful means to work with patterns in textual data. It makes it an indispensable part of a programmer's toolkit. Understanding and mastering regular expressions can significantly enhance one's ability to work.  

  

Fig: Preview of the output that you will get on running this code from your IDE.

Code


In this solution we are using Regex library of Python.

Searching a string with a Regex in Python

PythondotLines of Code : 30dotLicense : Strong Copyleft (CC BY-SA 4.0)

Dependent Libraries : 
import re

list_primary = ["Wi-Fi", "goat", "Access Point", "(683A1E320680)", "detected", "Access Point detected",  "2/5/2021", "10:44:45 PM",  "Local",  "41.289227",  "-72.958748"]
string1 = "Wi-Fi Access Point (683A1E320680) detected puppy Access Point detected 2/5/2021 10:44:45 PM Local 41.289227 -72.958748"
#Lattitude = re.findall("[0-9][0-9][.][0-9][0-9][0-9][0-9][0-9][0-9]")
#Longitude = re.findall("[-][0-9][0-9][.][0-9][0-9][0-9][0-9][0-9][0-9]")
string2 = string1.split('"')
# print(string2)

list1 = []

for item in string2:

    data_dict = {}

    date_field = re.search(r"(\d{1,2})[/.-](\d{1,2})[/.-](\d{4})",item)
    print(date_field)

    if date_field is not None:
        date = date_field.group()
    else:
        date = None

re.Match object; span=(71, 79), match='2/5/2021'>

date_field = re.findall(r"(\d{1,2}[/.-]\d{1,2}[/.-]\d{4})",string1)
print(date_field)

['2/5/2021']

Instructions


Follow the steps carefully to get the output easily.


  1. Download and Install the PyCharm Community Edition on your computer.
  2. Open the terminal and install the required libraries with the following commands.
  3. Install Pyglet - pip install Pyglet.
  4. Create a new Python file on your IDE.
  5. Copy the snippet using the 'copy' button and paste it into your Python file.
  6. Remove only 24 and 29 lines from the code.
  7. Run the current file to generate the output.


I hope you found this useful.


I found this code snippet by searching for 'Searching a string with a Regex in Python' in Kandi. You can try any such use case!

Environment Tested


I tested this solution in the following versions. Be mindful of changes when working with other versions.

  1. PyCharm Community Edition 2023.2
  2. The solution is created in Python 3.8 Version
  3. Regex 2023.10.3 Version.


Using this solution, we can be able to use search function in python regex with simple steps. This process also facilities an easy way to use, hassle-free method to create a hands-on working version of code which would help us to use search function in python regex.

Dependent Library


regexby rust-lang

Rust doticonstar image 2897 doticonVersion:1.0.0doticon
License: Permissive (Apache-2.0)

An implementation of regular expressions for Rust. This implementation uses finite automata and guarantees linear time matching on all inputs.

Support
    Quality
      Security
        License
          Reuse

            regexby rust-lang

            Rust doticon star image 2897 doticonVersion:1.0.0doticon License: Permissive (Apache-2.0)

            An implementation of regular expressions for Rust. This implementation uses finite automata and guarantees linear time matching on all inputs.
            Support
              Quality
                Security
                  License
                    Reuse

                      You can search for any dependent library on kandi like 'regex'.

                      FAQ 

                      1. What are regular expression patterns and how do they work in Python Re search?  

                      Regular expression patterns are sequences of characters that define a search pattern. These patterns can include both literal characters and special characters. In Python, regular expression patterns are often used with the re module for searching it.  

                        

                      2. How does a regular Python string differ from pattern matches in Python Re search?  

                      Regular Python string literals and regular expression patterns used in Python's re modules.  

                      • Escaping  
                      • Raw String Literal  
                      • Metacharacters  
                      • Quantifiers and Special Sequences  

                        

                      3. What are identifiers, and how do they help parse data when using Python Re search?  

                      The identifiers are names given to entities like variables, functions, classes, and modules.  

                      • It must start with a letter (a-z, A-Z) or an underscore (_).  
                      • The remaining characters can be letters, digits (0-9), or underscores.  
                      • Identifiers are case-sensitive (myVar and myvar are different).  

                        

                      4. How does the last matched capturing group refine results in Python Re search?  

                      The regular expression pattern contains many capturing groups. It can access the text matched by the last capturing group. It does this using the special identifier \g<index> within the pattern itself.  

                      • (\w+): Matches and captures one or more-word characters (letters, digits, or underscores).  
                      • -: Matches a hyphen.  
                      • (\d+): Matches and captures one or more digits.  
                      • -: Matches another hyphen.  
                      • (\w+): Matches and captures one or more-word characters.  

                        

                      5. What are effective tips for optimizing parser functions in Python Re search programs??  

                      Creating efficient parser functions using Python's re module. This involves a combination of good practices, optimization techniques, and understanding regular expressions.  

                      • Regular Expressions  
                      • Raw String Literals  
                      • Limit Greedy Quantifiers  
                      • Optimize Character Classes  
                      • Avoid Backtracking  
                      • Grouping and Capturing  
                      • Named Capturing Groups  
                      • Profiling and Testing  
                      • Third-Party Libraries  

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