Advanced Strings

String objects have a variety of methods we can use to save time and add functionality. Lets explore some of them in this lecture:



In [75]:

    
s = 'hello world'

Changing case

We can use methods to capitalize the first word of a string, change cases to upper and lower case strings.



In [76]:

    
# Capitalize first word in string
s.capitalize()









    Out[76]:





'Hello world'



In [77]:

    
s.upper()









    Out[77]:





'HELLO WORLD'



In [78]:

    
s.lower()









    Out[78]:





'hello world'

Location and Counting



In [80]:

    
s.count('o')









    Out[80]:





2



In [81]:

    
s.find('o')









    Out[81]:





4

Formatting

The center() method allows you to place your string 'centered' between a provided string with a certain length. Personally, I've never actually used this in code as it seems pretty esoteric...



In [83]:

    
s.center(20,'z')









    Out[83]:





'zzzzhello worldzzzzz'

expandtabs() will expand tab notations \t into spaces:



In [84]:

    
'hello\thi'.expandtabs()









    Out[84]:





'hello   hi'

is check methods

These various methods below check it the string is some case. Lets explore them:



In [40]:

    
s = 'hello'

isalnum() will return True if all characters in S are alphanumeric



In [41]:

    
s.isalnum()









    Out[41]:





True

isalpha() wil return True if all characters in S are alphabetic



In [43]:

    
s.isalpha()









    Out[43]:





True

islower() will return True if all cased characters in S are lowercase and there is at least one cased character in S, False otherwise.



In [44]:

    
s.islower()









    Out[44]:





True

isspace() will return True if all characters in S are whitespace.



In [45]:

    
s.isspace()









    Out[45]:





False

istitle() will return True if S is a title cased string and there is at least one character in S, i.e. uppercase characters may only follow uncased characters and lowercase characters only cased ones. Return False otherwise.



In [47]:

    
s.istitle()









    Out[47]:





False

isupper() will return True if all cased characters in S are uppercase and there is at least one cased character in S, False otherwise.



In [35]:

    
s.isupper()









    Out[35]:





False

Another method is endswith() which is essentially the same as a boolean check on s[-1]



In [69]:

    
s.endswith('o')









    Out[69]:





True

Built-in Reg. Expressions

Strings have some built-in methods that can resemble regular expression operations. We can use split() to split the string at a certain element and return a list of the result. We can use partition to return a tuple that includes the separator (the first occurrence) and the first half and the end half.



In [52]:

    
s.split('e')









    Out[52]:





['h', 'llo']



In [72]:

    
s.partition('e')









    Out[72]:





('h', 'e', 'llo')



In [58]:

    
s









    Out[58]:





'hello'

Great! You should now feel comfortable using the variety of methods that are built-in string objects!