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Python Regex

Regular expressions in Python are called “Regex”. In python, they are mainly used to match strings of text like the particular characters, words, or maybe patterns of characters. This means that we can match and extract any string pattern from the text with the help of regular expressions where we have used two terms match and extract and both the terms have a slightly different meaning. We still have cases when we want to match a specific pattern but also have to extract a subset of it. For example, when we want to match a specific pattern but can extract a subset of it. When we compare the Dr. XYZ keyword and also remove only the name that is “XYZ” that is not prefixed “Dr” from the list. Regex is very useful in searching all the texts by the big programming language for the string that is matching. When we bifurcate the regular expressions and also their implementation in python it will be very important to know their applications which is in the real world.

There are many applications.  Some of them are:

  • Data Mining:

We cannot remember the importance of regex data mining when the data will be available in the unstructured format that is in the text form it needs to convert to the numbers for the training in the model. So here Regex plays an important role in analyzing the data, finding the pattern in the data, and also performing the operations on the dataset.

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  • NLP

It is a process by which a computer that understands and generates the human language. In NLP the regular expression is used to remove the unnecessary words like stop words from the text which supports data cleaning. Regex is also used to analyze the texts and thus also helps in the prediction of the algorithm to process the data.

Wild card patterns

There are tiny individual units wherefrom the regular expressions which are formed are called wild card patterns. This list will show commonly used patterns:

^  – This wild card pattern matches the character which is at the beginning of a line.

$ – This wild card pattern matches the character at the end of the line.

.  – This wild card pattern matches any character in the line.

s – This wild card matches non-whitespace characters.

d – This wild card will match one digit

  • – This wild card repeats any one of the  previous character zero or may be more times.
  • – This will repeats any one previous character may be many more times. It compares the largest possible string that is following pattern.

There are some examples like:

Suppose we want to fetch numbers from a document, the regex  will be :[0-9]+

If we want to fetch all the characters other than numbers regex will be:[^0-9]+

To fetch a pattern like a name starts from the document with “A” and ends with “h” the regex will be:^A[a-zA-Z]+h$

Implementation in python:

Here python does not contain an inbuilt regex module. We may install using the pip command and then import it into the python IDE. Then we stored some text in the variable named string

pip install re

import re

string = “ H2K INFOSYS provides world-class QA & BA training.”

Match method()

The function searches for RE pattern at the beginning of the string and returns the match object of the string. This value of any object can be accessed through the group() function. The main syntax is

re.match(pattern,string,flags)

Here is the pattern that shows the regular expressions, the string represents the text that will be searched to match the pattern and the flags that represent the modifiers. This is an optional parameter.

  1. What is the importance of Python Regex?
  2. How Python Regex can be implemented in Python? Give example
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  1. Regular expressions in Python are called “Regex”. In python, they are mainly used to match strings of text like the particular characters, words, or maybe patterns of characters. This means that we can match and extract any string pattern from the text with the help of regular expressions where we have used two terms match and extract and both the terms have a slightly different meaning. We still have cases when we want to match a specific pattern but also have to extract a subset of it. For example, when we want to match a specific pattern but can extract a subset of it. When we compare the Dr. XYZ keyword and also remove only the name that is “XYZ” that is not prefixed “Dr” from the list. Regex is very useful in searching all the texts by the big programming language for the string that is matching. When we bifurcate the regular expressions and also their implementation in python it will be very important to know their applications which is in the real world
    Implementation in python:

    Here python does not contain an inbuilt regex module. We may install using the pip command and then import it into the python IDE. Then we stored some text in the variable named string

    pip install re

    import re

    string = “ H2K INFOSYS provides world-class QA & BA training.”

    Match method()

    The function searches for RE pattern at the beginning of the string and returns the match object of the string. This value of any object can be accessed through the group() function. The main syntax is

    re.match(pattern,string,flags)

    Here is the pattern that shows the regular expressions, the string represents the text that will be searched to match the pattern and the flags that represent the modifiers. This is an optional parameter.

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