This article was published as a part of the Data Science Blogathon
Introduction
Python string is a built-in type sequence. Strings can be used to handle textual data in Python. Python Strings are immutable sequences of Unicode points. Creating Strings is the simplest and easy to use in Python. To create a string in Python, we simply enclose a text in single as well as double-quotes. Python treats both single and double quotes statements the same. So, In this article, we will be discussing some important and useful Functions of Strings in Python for Data Analysis and Data Manipulation, mainly used in Natural Language Processing(NLP).
To follow this article properly, I assume you are familiar with the basics of Python. If not, I recommend the below popular course given by Analytics Vidhya to get started with the Python Basics:
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Python String Functions
The Python String Functions which we are going to discuss in this article are as follows:
- capitalize( ) function
- lower( ) function
- title( ) function
- casefold( ) function
- upper( ) function
- count( ) function
- find( ) function
- replace( ) function
- swapcase( ) function
- join( ) function
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capitalize( ) function
The capitalize() function returns a string where the first character is the upper case.
Python Code:
Example 2: What happens if the first character is a number instead of a character
string = '10 version of Data Science Blogathon by Analytics Vidhya is very good' print(string.capitalize())
Output:
10 version of data science blogathon by analytics vidhya is very good
lower( ) function
The lower() function returns a string where all the characters in a given string are lower case. This function doesn’t do anything with Symbols and Numbers i.e, simply ignored these things.
Syntax: string.lower()
Example 1: Lower case the given string
string = "Analytics Vidhya is the Largest Data Science Community" print(string.lower())
Output:
analytics vidhya is the largest data science community
Example 2: What happens if there is a number instead of a character
string = '10 version of Data Science Blogathon by Analytics Vidhya is very good' print(string.lower())
Output:
10 version of data science blogathon by analytics vidhya is very good
title( ) function
The title() function returns a string where the first character in every word of the string is an upper case. It is just like a header, or a title.
If in a string any of the words contain either a number or a symbol, then this function converts the first letter after that to upper case.
Syntax: string.title()
Example 1: Make the first letter in each word upper case
string = "analytics vidhya is the Largest data science Community" print(string.title())
Output:
Analytics Vidhya Is The Largest Data Science Community
Example 2: What happens if there is a number instead of a character
string = '10th version of Data Science Blogathon by Analytics Vidhya is very good' print(string.title())
Output:
10Th Version Of Data Science Blogathon By Analytics Vidhya Is Very Good
casefold( ) function
The casefold() function returns a string where all the characters are lower case.
This function is similar to the lower() function, but the casefold() function is stronger, more aggressive, meaning that it will convert more characters into lower case and will find more matches when comparing two strings and both are converted using the casefold() function.
Syntax: string.casefold()
Example 1: Make the given string to lower case
string = "Analytics Vidhya is the Largest Data Science Community" print(string.casefold())
Output:
analytics vidhya is the largest data science community
Example 2: What happens if there is a number instead of a character
string = '10th version of Data Science Blogathon by Analytics Vidhya is very good' print(string.casefold())
Output:
10th version of data science blogathon by analytics vidhya is very good
upper( ) function
The upper() function returns a string where all the characters in a given string are in the upper case. This function doesn’t do anything with Symbols and Numbers i.e, simply ignored these things.
Syntax: string.upper()
Example 1: Upper case the given string
string = "analytics Vidhya is the Largest Data Science Community" print(string.upper())
Output:
ANALYTICS VIDHYA IS THE LARGEST DATA SCIENCE COMMUNITY
Example 2: What happens if there is a number instead of a character
string = '10th version of Data Science Blogathon by Analytics Vidhya is very good' print(string.upper())
Output:
10TH VERSION OF DATA SCIENCE BLOGATHON BY ANALYTICS VIDHYA IS VERY GOOD
count( ) function
The count() function finds the number of times a specified value(given by the user) appears in the given string.
Syntax: string.count(value, start, end)
Example 1: Return the number of times the value “analytics” appears in the string
string = "analytics Vidhya is the Largest Analytics Community"
print(string.count("analytics"))
Output:
1
Example 2: Return the number of times the value “analytics” appears in the string from position 10 to 18
string = "analytics Vidhya is the Largest analytics Community"
print(string.count("analytics", 10, 18))
Output:
0
find( ) function
The find() function finds the first occurrence of the specified value. It returns -1 if the value is not found in that string.
The find() function is almost the same as the index() function, but the only difference is that the index() function raises an exception if the value is not found.
Syntax: string.find(value, start, end)
Example 1: Where in the text is the first occurrence of the letter “d”?
string = "analytics vidhya is the Largest data science Community"
print(string.find("d"))
Output:
12
Example 2: Where in the text is the first occurrence of the letter “d” when you only search between positions 5 and 16?
string = "analytics vidhya is the Largest data science Community"
print(string.find("d", 5, 16))
Output:
12
Example 3: If the value is not found, the find() function returns -1, but the index() function will raise an exception
string = "analytics vidhya is the Largest data science Community"
print(string.find("d", 5, 10))
Output:
-1
replace( ) function
The replace() function replaces a specified phrase with another specified phrase.
Note: All occurrences of the specified phrase will be replaced if nothing else is specified.
Syntax: string.replace(oldvalue, newvalue, count)
Example 1: Replace all occurrences of the word “science”
string = "analytics vidhya is the Largest data science Community"
print(string.replace("science", "scientists"))
Output:
analytics vidhya is the Largest data scientists Community
Example 2: Replace only the first occurrence of the word “science”
string = "Data science Courses by analytics vidhya are the best courses to learn Data science"
print(string.replace("science", "scientists", 1))
Output:
Data scientists Courses by analytics vidhya are the best courses to learn Data science
swapcase( ) function
The swapcase() function returns a string where all the upper case letters are lower case and vice versa.
Syntax: string.swapcase()
Example 1: Make the lower case letters to upper case and the upper case letters to lower case
string = "analytics vidhya is the Largest data science Community" print(string.swapcase())
Output:
ANALYTICS VIDHYA IS THE lARGEST DATA SCIENCE cOMMUNITY
Example 2: What happens if there is a number instead of a character
string = '10th version of Data Science Blogathon by Analytics Vidhya is very good' print(string.swapcase())
Output:
10TH VERSION OF dATA sCIENCE bLOGATHON BY aNALYTICS vIDHYA IS VERY GOOD
join( ) function
The join() function takes all items in an iterable and joins them into one string. We have to specify a string as the separator.
Syntax: string.join(iterable)
Example 1: Join all the items in a given tuple into a string, using a # (hashtag) character as the separator
myTuple = ("Data Scientists", "Machine Learning", "Data Science")
x = "#".join(myTuple)
print(x)
Output:
Data Scientists#Machine Learning#Data Science
Example 2: Join all the items in a given dictionary into a string, using the word “TEST” as the separator
myDict = {"name": "Analytics Vidhya", "country": "India", "Technology": "Data Science"}
mySeparator = "TEST"
x = mySeparator.join(myDict)
print(x)
Output:
nameTESTcountryTESTTechnology
Other Blog Posts by Me
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End Notes
Thanks for reading!
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I am currently pursuing my Bachelor of Technology (B.Tech) in Computer Science and Engineering from the Indian Institute of Technology Jodhpur(IITJ). I am very enthusiastic about Machine learning, Deep Learning, and Artificial Intelligence. Feel free to connect with me on Linkedin.
