Strings¶

String Methods¶

Changing Case Methods¶

Method for changing character cases:

Method	Purpose
`capitalize()`	Converts the first character to upper case
`lower()`	Converts a string into lower case
`swapcase()`	Swaps cases, lower case becomes upper case and vice versa
`title()`	Converts the first character of each word to upper case
`upper()`	Converts a string into upper case

Try them out with this code:

sample = "a long time Ago in a Galaxy far far away"

print(sample.capitalize())
print(sample.lower())
print(sample.swapcase())
print(sample.title())
print(sample.upper())

Substring Methods¶

These methods return information about substrings in the string

Method	Purpose
`count()`	Returns the number of times a specified value occurs in a string
`find()`	Searches the string for a specified value and returns the position of where it was found
`index()`	Searches the string for a specified value and returns the position of where it was found
`rfind()`	Searches the string for a specified value and returns the last position of where it was found
`rindex()`	Searches the string for a specified value and returns the last position of where it was found

Try them out with this code:

sample = "banna"

print(sample.count("a"))
print(sample.find("a"))
print(sample.index("a"))
print(sample.rfind("a"))
print(sample.rindex("a"))

String Comparison Methods¶

These methods evaluate a string and return a Boolean value

Method	Purpose
`endswith()`	Returns true if the string ends with the specified value
`isalnum()`	Returns True if all characters in the string are alphanumeric
`isalpha()`	Returns True if all characters in the string are in the alphabet
`isascii()`	Returns True if all characters in the string are ascii characters
`isdecimal()`	Returns True if all characters in the string are ASCII decimals
`isdigit()`	Returns True if all characters in the string are digits
`isidentifier()`	Returns True if the string is an valid variable name
`islower()`	Returns True if all characters in the string are lower case
``isnumeric()`	Returns True if all characters in the string can be used as numbers such as digits, fractions, subscripts, superscripts, Roman numerals, currency numerators etc.
`isprintable()`	Returns True if all characters in the string are printable
`isspace()`	Returns True if all characters in the string are whitespaces
`istitle()`	Returns True if the string follows the rules of a title
`isupper()`	Returns True if all characters in the string are upper case
`startswith()`	Returns true if the string starts with the specified value

Try them out with this code:

print("Melancholy".endswith("ly"))
print("R2D2".isalnum())
print("C3PO".isalpha())
print("X-wing".isascii())
print("0456 784 907".isdecimal())
print("0345".isdigit())
print("first_name".isidentifier())
print("Juxtaposition".islower())
print("45".isnumeric())
print("\nhello".isprintable())
print("  ".isspace())
print("Ethereal".istitle())
print("Maelstrom".isupper())
print("Luminescent".startswith("le"))

String Justification Methods¶

Justification adds ‘padding’ characters to a string so it becomes a set length.

Method	Purpose
`center()`	Will center align the string, using a specified character (space is default) as the fill character.
`ljust()`	Will left align the string, using a specified character (space is default) as the fill character.
`rjust()`	Will right align the string, using a specified character (space is default) as the fill character.

Try them out with this code:

sample = "word"

print(sample.center(20))
print(sample.center(20, "_"))
print(sample.ljust(20))
print(sample.ljust(20,"_"))
print(sample.rjust(20))
print(sample.rjust(20,"_"))

String Modification Methods¶

These methods will modify a string

Method	Purpose
`join()`	Converts the elements of an iterable into a string
`lstrip()`	Returns the string with the leading whitespace characters (spaces, tabs, newlines) removed
`replace()`	Returns a string where a specified value is replaced with a specified value
`rsplit()`	Splits the string at the specified separator from right to left, and returns a list
`rstrip()`	Returns the string with the trailing whitespace characters (spaces, tabs, newlines) removed
`split()`	Splits the string at the specified separator from left to right, and returns a list
`splitlines()`	Splits the string at line breaks and returns a list
`strip()`	Returns a trimmed version of the string with leading a trailing whitespace removed.

Try them out with this code:

sample = "A long time ago in a galaxy far far away"
sample_list = ["Use", "the", "Force"]
sample_whitespace = "    Jawa    "
sample_lines = "Help me Obi Wan Kenobi\nYou are my only hope"

print(" ".join(sample_list))
print(sample_whitespace.lstrip())
print(sample.replace("Force", "fork"))
print(sample.rsplit(" ",3))
print(sample_whitespace.rstrip())
print(sample.split(" ",3))
print(sample.rsplit(" "))
print(sample_lines)
print(sample_lines.splitlines())
print(sample_whitespace.strip())