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In this blog, we will be reviewing Python’s built-in methods to operate on Strings. You can use these methods to perform boolean checks and replace or change the form of the string. 

Code Samples

upper

The `upper()` method changes all lowercase alphabets into uppercase.

text = 'knoWledge dIsCoverY NuggETS'
 
# Converting string to uppercase
new_string = text.upper()
print(f"Before: {text}\nAfter: {new_string}\n")

Before: knoWledge dIsCoverY NuggETS
After: KNOWLEDGE DISCOVERY NUGGETS

replace

The `replace()` method requires two arguments to replace all occurrences of a substring with another substring. 

# Replacing the string
new_string = text.replace("knoWledge dIsCoverY ","KD")
print(f"Before: {text}\nAfter: {new_string}\n")

Before: knoWledge dIsCoverY NuggETS
After: KDNuggETS

find

The `find()` will search for a substring and if it is found, it will return the lowest index of the substring.

# Find the string
new_string = text.find("dIsCoverY")
print(f"The string is at {new_string} index\n")

The string is at 10 index

isnumeric

The `isnumeric()` method returns “True” if all of the characters in the string are numeric.

# Is the text numerical?
new_string = text.isnumeric()
print(f"Is the text numerical? {new_string}\n")

print(f"Is·the·text·numerical?·{new_string}\n")
#·Is·the·text·numerical?
new_string·=·text.isnumeric()

Is the text numerical? False

List of all Python String Methods

Case Change

• lower(): it changes all uppercase characters to lowercase. 
• capitalize(): it changes the first character of the string to uppercase.
• upper(): it changes all lowercase characters to uppercase. 
• title(): it changes string to title case. 
• casefold(): it implements caseless string matching.
• swapcase(): it changes all uppercase characters to lowercase and lowercase to uppercase. 

Checks

• startswith(): it returns “True” if the string starts with the given substring. 
• endswith(): it returns “True” if the string ends with the given substring. 
• isalnum(): it checks if all characters in the string are alphanumeric or not.
• isalpha(): it checks if all characters in the string are alphabets or not.
• isdecimal(): it checks if all characters in the string are decimal or not.
• isdigit(): it checks if all characters in the string are digits or not.
• isidentifier(): it checks if the string is a valid identifier or not.
• islower(): it checks if all characters in the string are lowercase or not.
• isnumeric(): it checks if all characters in the string are numeric or not.
• isprintable(): it returns “True” if all characters in the string are printable or the string is empty
• isspace(): it checks if all characters in the string are whitespace characters or not.
• istitle(): it checks if all characters in the string are title case or not.
• isupper(): it checks if all characters in the string are uppercase or not.

Split and Join

• join(): it returns a concatenated string.
• partition(): it splits the string on the first occurrence of the separator. 
• rpartition(): it splits the string into three parts.
• rsplit(): it splits the string from the right using a specified separator.
• splitlines(): it splits the lines at line boundaries.
• split(): it splits the string using a specified separator.

Padding and Cleaning

• center(): Pad the string with the specified character.
• ljust(): It left aligned the string using the specified width. 
• rjust(): It right aligned the string using the specified width. 
• lstrip(): it removes the leading characters from the string. 
• rstrip(): it removes the trailing characters from the string. 
• strip(): it removes both leading and trailing characters from the string. 
• zfill(): it returns a copy of the string with ‘0’ characters padded to the left side of the string.

Find and Replace

• encode(): it encodes the string using a specified encoding scheme.
• find(): it returns the lowest index of the specified substring.
• rfind(): it returns the heights index of the specified substring.
• index(): it returns the position of the first occurrence of a substring in a string.
• rindex(): it returns the highest index of the substring inside the string.
• replace(): it requires two arguments to replace all occurrences of a substring with another substring. 

Miscellaneous  

• count(): it counts the number of occurrences of a substring in the string. 
• expandtabs(): it specifies the amount of space to be substituted with the “\t” symbol in the string.
• maketrans(): it returns a translation table.
• translate(): it changes the string using translation mappings.
• format(): it formats the string for console printing. 
• format_map(): it formats specified values in a string using a dictionary. 

Learning Resources 

• Python String Tutorial
• Python String - GeeksforGeeks
• 31 ESSENTIAL Python String Methods - YouTube

 
 
Abid Ali Awan (@1abidaliawan) is a certified data scientist professional who loves building machine learning models. Currently, he is focusing on content creation and writing technical blogs on machine learning and data science technologies. Abid holds a Master's degree in Technology Management and a bachelor's degree in Telecommunication Engineering. His vision is to build an AI product using a graph neural network for students struggling with mental illness.