Python find second substring

Extract substring between two markers in Python

In this article, we will learn to extract a substring between two markers in a string using Python Programming Language. But before that we should know what is a substring in Python programming language?

A substring is a sequence of characters which is a part of a string often created using methods like slicing or by using split() method. Now let’s learn about the methods through which we can extract the given substring between two markers.

Table Of Contents

Extract substring between two markers using Regex

First method we will be using to extract a given substring between two markers is by using the search() method of re module. The re stands for Regular Expression which comes bundled with the Python Programming Language.

The re.search(pattern) methods returns the string found which matches the given pattern. It stops as soon as it locates the mathcing string and returns the string. If no match s found then t returns None.

Frequently Asked:

import re sampleStr = 'ilearncodingfrom;thispointer.com/articles' try : # here ; and / are our two markers # in which string can be found. marker1 = ';' marker2 = '/' regexPattern = marker1 + '(.+?)' + marker2 str_found = re.search(regexPattern, sampleStr).group(1) except AttributeError: # Attribute error is expected if string # is not found between given markers str_found = 'Nothing found between two markers' print(str_found)

So in the code and output above, you can see that by using the re.search() method, we have successfully found the substring between given two markers.Here we need to look for the string between two markers (; and /) in variable sampleStr. Also we are expecting AttributeError if nothing is found between the given two markers. So, if find nothing between the given two markers(; and /) then instead of giving an AttributeError , it will return a message nothing found between two markers.

Extract substring between two markers using find() and slice()

To extract the substring between two markers, we will be using a combination of find() method and slicing method of Python Programming language. The
find() method will be used to find the string between two markers. It returns -1 if found nothing. Then we will use slice() method to slice the substring in between given two markers. Lets see an example :

sampleStr = 'ilearncodingfrom;thispointer.com/articles' # find() method will search the # given marker and stores its index mk1 = sampleStr.find(';') + 1 # find() method will search the given # marker and sotres its index mk2 = sampleStr.find('/', mk1) # using slicing substring will be # fetched in between markers. subString = sampleStr[ mk1 : mk2 ] print(subString)

In the code and output of method 2, you can see that a combination of slice() method and find() methods has been used to extract substring between two markers. Index of markers has been sotred in var mk1 and mk2 using the find() method. Then using slicing, substring has been fetched and printed.

Extract substring between two markers using split() method

Next method that we will be using is the split() method of Python Programming language, to extract a given substring between two markers. The split() method in python splits the given string from a given separator and returns a list of splited substrings.

It recieves two parameters :
– separator : separator used to split the string. If given nothing is provided, then space is the default separator.
– maxsplit : a number, which specifies the maximum parts in which the string needs to be splitted. Default value is -1 which specifies there is no limit.

Lets see an example of this method :

sampleStr = 'ilearncodingfrom;thispointer.com/articles' # here ; and / are our two markers # in which string can be found. subStr = sampleStr.split(';')[1].split('/')[0] print(subStr)

In the code above, its just a one line code comprising multiple split() methods, through which substring has been extracted between two markers. First split() method splits the string from marker ‘;’ and its index 1 has been used in which rest part of the string lies. Then again split() method has been used. But now marker ‘/’ is the separator and it splits the substring from rest of the string and index 0 is printed.

Extract substring between two markers using partition() method :

Next method we will be using to extract the substring between two markers is partition() method. The partition() method splits the string from first occurence and returns a tuple containing three items :

• Firts : string before the given separator.
• Second : separator
• Third : string after the given separator.

It receives only one parameter which is the separator.

sampleStr = 'ilearncodingfrom;thispointer.com/articles' before, mk1, after = sampleStr.partition(";") subStr, mk2, after = after.partition("/") print(subStr)

In the code and output above you can see how partition() method has been used to extract substring between two markers.
irst we partioned the string based on first marker. It splitted the string into three parts i.e. substring before first market, the first marker and the substring after the first marker. We picked the last one i.e. the substring after the first marker. Then we partioned that based on second marker and picked the first entry from returned tuple. This first entry denotes the sbstring before second marker. So as a result we got our substring between two given markers.

Summary

In this article, we learned about substrings and markers. Then we also discussed about four different methods through which we can extract the substring between two markers. Method 1 and Method 3 can be very helpful because method 1 has the better error handling. Whereas, method 3 has a shorter syntax and easier to understand. Otherwise all the methods above are very useful. Try to learn all the methods above and run these codes on your machines. We have used Python 3.10.1 for writing example codes. To check your version write python –version in your terminal.

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Discover 5 Simple Ways to Find the Second Occurrence of a Substring in Python Strings

Learn how to find the second occurrence of a substring in Python strings with 5 easy methods. Count, split, and use the find() method to manipulate strings. Try it now!

• Use the find() method to find the first occurrence of the substring.
• Add the length of the substring to the index found in the previous step to get the starting index of the second occurrence.
• Use the find() method again with the updated starting index to find the second occurrence.
• Use the split() method to divide the string at the substring with max n+1 splits to locate the nth occurrence of a substring in a string.
• Use the count() method to find the number of times a specified value appears in the string.
• Other quick code examples for finding the second occurrence of a substring in Python strings
• Conclusion
• How do you find the second occurrence of a string in Python?
• How to find second repeated characters in a string in Python?
• How to find the nth occurrence of a character in a string in Python?
• How do you find the occurrences of a string in a string Python?

Python is a versatile and powerful programming language that offers a variety of tools for working with strings. String manipulation is a common task in programming, and finding the second occurrence of a substring in a string is one such task. In this article, we will explore different methods to find the second occurrence of a substring in a string using Python. By the end of this article, you will have a clear understanding of how to find the second occurrence of a substring in a string using Python.

Use the find() method to find the first occurrence of the substring.

The find() method is a built-in method in Python that returns the index of the first occurrence of the substring in the string. If the substring is not found, the method returns -1. To find the first occurrence of the substring, you can use the following code:

Here, string is the string in which you want to find the substring, and substring is the substring you want to find.

Add the length of the substring to the index found in the previous step to get the starting index of the second occurrence.

To find the starting index of the second occurrence of the substring, you can add the length of the substring to the index found in the previous step. Here is an example:

string.find(substring, string.find(substring)+len(substring)) 

In this code, string.find(substring) returns the index of the first occurrence of the substring. We add the length of the substring to this index to get the starting index of the second occurrence.

Use the find() method again with the updated starting index to find the second occurrence.

Once you have the starting index of the second occurrence, you can use the find() method again with the updated starting index to find the second occurrence of the substring. Here is an example:

string.find(substring, string.find(substring)+len(substring)) 

In this code, string.find(substring) returns the index of the first occurrence of the substring. We add the length of the substring to this index to get the starting index of the second occurrence. We then pass this starting index as the second argument to the find() method to find the second occurrence of the substring.

Use the split() method to divide the string at the substring with max n+1 splits to locate the nth occurrence of a substring in a string.

The split() method is a built-in method in Python that can be used to divide a string at a specified separator. To locate the nth occurrence of a substring in a string, you can use the split() method with the following code:

Here, string is the string in which you want to locate the nth occurrence of the substring, substring is the substring you want to locate, and n is the occurrence number. The split() method divides the string at the substring with max n+1 splits, and the -1 index returns the last element of the resulting list, which is the substring you are looking for.

Use the count() method to find the number of times a specified value appears in the string.

The count() method is a built-in method in Python that can be used to count the number of times a specified value appears in a string. To count the number of times a substring appears in a string, you can use the count() method with the following code:

Here, string is the string in which you want to count the number of times the substring appears, and substring is the substring you want to count.

Other quick code examples for finding the second occurrence of a substring in Python strings

In Python , python find second occurrence in string

# find index of second occurence of substring in string idx = string.find(substring, string.find(substring) + 1) 

Conclusion

Python provides several methods to find the second occurrence of a substring in a string. The find() method can be used to find the first and second occurrences of the substring. The split() method can be used to locate the nth occurrence of a substring in a string. The count() method can be used to count the number of times a specified value appears in the string. By using these methods, developers can easily manipulate strings and perform complex operations.

In conclusion, finding the second occurrence of a substring in a string is a common task in string manipulation, and Python offers several built-in methods to accomplish this task. By using the find() method, the split() method, and the count() method, developers can easily manipulate strings and perform complex operations. We hope this article has been helpful in providing you with a clear understanding of how to find the second occurrence of a substring in a string using Python.

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