String methods, unlike list methods, return new strings, not changed strings. This is because strings are immutable.
.lower() and .upper() are methods that return lower and upper case versions of those strings respectively.
In [7]:
spam = 'Hello World!'
print(spam)
print(spam.upper())
print(spam.lower())
print(spam) # variable is unmodified
This methods are useful for case insensitive inputs.
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answer = input()
if answer == 'yes':
print('Playing again.')
This fails if we use capitals. Instead, we can make the input insensitive.
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answer = input()
if answer.lower() == 'yes':
print('Playing again.')
.islower() and .isupper() return boolean responses about the case of the string. There must be at least one upper or lower character to function.
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print(spam.islower())
print(spam.upper().isupper()) # Double methods; works because spam.upper() is its own string.
There are other 'checking' methods that can be used:
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print('hello'.isalpha()) # letters only
print('hello123'.isalnum()) # alphanumeric only
print('123'.isdecimal()) # numbers only
print(' '.isspace()) # whitespace only
print('Hello world!'[5].isspace()) # This index of this string is whitespace
print('This Is Title Case'.istitle()) # Titlecase only
There are also .startwith() and .endwith() methods:
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print('Hello world!'.startswith('Hello')) # True
print('Hello world!'.startswith('H')) # True
print('Hello world!'.startswith('ello')) # False
print('Hello world!'.endswith('world!')) # True
print('Hello world!'.endswith('world')) # False
The .join() method joins strings/lists.
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print(','.join(['cats','rats','bats']))
print(' '.join(['cats','rats','bats']))
print('\n\n'.join(['cats','rats','bats']))
The .split() method does the opposite:
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print('My name is Simon'.split()) # Default is whitespace split
print('My name is Simon'.split('m')) # Split by m
The .ljust(), .rjust(), and .center() left, right, and center justify.
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print('Hello'.rjust(10))
print('Hello'.ljust(10))
print('Hello'.ljust(25,'-')) # Other justify parameter
name = 'Al'
print(name.center(20,'='))
The .strip() method strips whitespace.
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spam = ' Hello'
print(spam)
print(spam.strip())
print(spam) # Remember, strings are immutable; they are not changed via methods
print(' x '.lstrip()) # Can also left strip
print(' x '.rstrip()) # Or right strip
print('SpamSpamBaconSpamEggsSpamSpam'.strip('Spam')) # Can even strip out string characters
The .replace() string method does this better.
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print(spam)
print(spam.replace('e','XYZ')) # replace e with XYZ
The Pyperclip Module can be used to copy text to and from the keyboard.
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import pyperclip
# Use pip to install packages into the Python3.5/scripts directory
pyperclip.copy('Hello!') # Copies to clipboard
pyperclip.paste() # Pastes whatever is on clipboard
Out[42]:
.upper() and .lower() return an uppercase or lowercase string..isupper(), .islower(), .isalpha, .isalnum, .isdecimal, .isspace(), and .istitle() return Boolean True/False statements about the string..startswith() and .endswith() also return bools..join() joins strings in a list with the parameter passed to it..split() splits its string into a list of strings using the paramater..rjust(), .ljust(), and .center() returns a string padded with parameters. .replace() replaces all occurences of the first argument with the second argument..copy() and .paste() functions for using the clipboard.