Python program to print all patterns in a file that match a given pattern

Finding lines in a file that match a specific pattern is a typical operation in many applications, such as log analysis, text processing, and data filtering. In this article, we will discuss a Python program for printing all patterns in a file that match a given pattern. To solve this problem, we first create a schema in the file to save it. Our task is to programmatically create the exact pattern we see in the file. By applying some conditions, it will check if the pattern in the given file matches.

grammar

with open("file_name.txt", "r") as file

open() function opens a file together with the ‘with’ statement. The open function accepts two parameters - file_name.txt which represents the file name and "r" which represents the mode to open the file for reading.

File is an object type.

algorithm

The following steps are -

• Text file and create a pattern in the file and save it.

• We will start the program by creating the above pattern from the given file.

• Then use a for loop to iterate over the range from 1 to 6, creating rows 5 for the pattern design.

• Next, print out the pattern and match it against the text file by multiplying 'i' with '*'.

• We will check if the program matches the given file -

• Then initialize the variable 'contents' to read the file using the predefined function read().

• Go ahead and start the if-else statement, applying the condition in the variable 'content' - keyword aestrick(*) together with the special character '\n' to check whether an exact match of the pattern is found in the file.

• If an exact match is found, then it will print "Exact match found from file" , otherwise no match is found.

Example

In this program we will create a pattern similar to a given file and check if the pattern matches the file.

for i in range(1, 5):
   print("*"*i)
# Check the pattern for the exact matching
with open("pattern.txt", "r") as file:
   contents = file.read()
# special character of new line represented by \n.
   if "*\n**\n***\n****" in contents:
      print("Exact match found from file")
   else:
      print("Exact match not found.")

Output

*
**
***
****
*****
Exact match found!

Advantage

A pattern that matches a given pattern in a file has the following advantages -

• Efficient Data Extraction − This program can quickly and easily extract specific information from large amounts of data, such as log files or text documents.

• Data Analysis− The extracted information can be used for data analysis, text mining, and other applications that require finding specific information in large amounts of data.

• Built-in Functions and Libraries - Python allows the use of the re module, which helps in building pattern matching from files.

• Powerful and Flexible - Python is an advanced and flexible programming language that enables you to easily process and analyze data in a variety of ways.

in conclusion

We understand examples of patterns that match a given file. We saw how mode r helps in reading an open file and used the read() method to read the file. Then saw the importance of the special character "\n" which provides a new line to match each line of the pattern (*).

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