A brief discussion on the simple use of python string methods

Learn how to use python string methods, try out each method listed in the book, and record the results for future query.

(1) s.capitalize(); Function: Return a copy of the string and capitalize the first letter. Use as follows:

>>> s = 'wwwwww'
 >>> scap = s.capitalize()
 >>> scap 
 'Wwwwww'

(2) s.center(width,char); Function: Returns a string of length width with the s string placed in the middle. By default, other parts are filled with spaces, otherwise the char parameter is used to fill. Examples are as follows:

>>> s 
'wwwwww'
>>> s = 'wwwwww'
>>> scen = s.center(20)
>>> scen
'    wwwwww    '
>>> scen0 = s.center(20,'Y')
>>> scen0
'YYYYYYYwwwwwwYYYYYYY'
>>>

(3) s.count(t,start,end); Function: Return the number of string t in string s (or in a sub-segment of string). Examples are as follows:

>>> scen0
'YYYYYYYwwwwwwYYYYYYY'
>>> scoun = scen0.count('w',0,19)
>>> scoun
6

(4) s.endswith(x,start,end); Function: If s (or split with start and end) ends with the string x, return True, otherwise return False.

>>> scen0 
'YYYYYYYwwwwwwYYYYYYY'
>>> sends0 = scen0.endswith('Y',1,19)
>>> sends0
True
>>> sends1 = scen0.endswith('w',1,10)
>>> sends1
True

(5) s.find(t,start,end); Function: Return the leftmost position of string t in s (or start:end slice). If t is not found, return -1. Use s.rfind(t,start,end) to find the rightmost position of t. Examples are as follows:

>>> s
'YYYYYYYwwwwwwYYYYYYY'
>>> t = 'w'
>>> sfind = s.find(t,0,19)
>>> sfind
7
>>> srfind = s.rfind(t,1,19)
>>> srfind
12

(6) s.isalnum(); Function: If s is not empty and each character is alphanumeric, it returns True.

 >>> s
 'YYYYYYYwwwwwwYYYYYYY'
 >>> sisa = s.isalnum()
 >>> sisa
 True

(7)s.isalpha(); Function: If s is not empty and each character is a letter, it returns True

>>> s
'YYYYYYYwwwwwwYYYYYYY'
>>> sisal = s.isalpha()
>>> sisal
True

>>> s1
'ssss0000'
>>> sisal0 = s1.isalpha()
>>> sisal0
False

(8)s.isdigit(); Function: If s is not empty and each character is an ASCII digit, return True.

>>> sdigit = 'www000'
>>> sd = sdigit.isdigit()
>>> sd
False
>>> sdigit0 = '1234567890'
>>> sd0 = sdigit0.isdigit()
>>> sd0
True

(9)s.islower(); Function: If s has at least one lowercase character, and all lowercase characters are lowercase, return True.

>>> s0 = '1234567890'
>>> s0lower = s0.islower()
>>> s0lower
False

>>> s1 = '1234WWW'
>>> s1lower = s1.islower()
>>> s1lower
False


>>> s2 = '123456789w'
>>> s2lower = s2.islower()
>>> s2lower
True

(10) s.isspace(); Function: If s is not empty and each character in s is a blank character, it returns True.

>>> s = ''
>>> s0 = s.isspace()
>>> s0
False
>>> s = '  '
>>> s0 = s.isspace()
>>> s0
True

(11) s.istitle(); Function: If s is a non-empty string with the first letter capitalized, return True.

>>> s = 'wy'
>>> s0 = s.istitle()
>>> s0
False
>>> s = 'Wy'
>>> s0 = s.istitle()
>>> s0
True

(12)s.isupper(); Function: Returns True if s has at least one uppercase character and all uppercase characters are uppercase.

>>> s = 'wy'
>>> s0 = s.isupper()
>>> s0
False

>>> s = 'Wy'
>>> s0 = s.isupper()
>>> s0
False

>>> s = 'WY'
>>> s0 = s.isupper()
>>> s0
True

(13) s.join(seq); Function: Returns the result of the sequence seq after being connected, and s is between each two items.

>>> seq = 'WWWWWWW'
 >>> s = 'y'
 >>> snew = s.join(seq)
 >>> snew
 'WyWyWyWyWyWyW'

(14) s.lower(); Function: Change the characters in s to lowercase.

>>> snew
 'WyWyWyWyWyWyW'
 >>> s =snew.lower()
 >>> s
 'wywywywywywyw'

(15) s.replace(t,u,n); Function: Returns a copy of s, where each t (or at most n) is replaced with u.

>>> s
'wywywywywywyw'
>>> sre = s.replace('w','W')
>>> sre
'WyWyWyWyWyWyW'

>>> s
'wywywywywywyw'
>>> sre = s.replace('w','W',4)
>>> sre
'WyWyWyWywywyw'

(16) s.swapcase(); Function: Return a copy of s, and lowercase uppercase characters and uppercase lowercase characters.

>>> s = 'WyWyWyWy'
 >>> ssw = s.swapcase()
 >>> ssw
 'wYwYwYwY'

(17) s.zfill(w); Function: Return a copy of s. If it is shorter than w, add 0 at the beginning to make its length w.

>>> s = 'www'
 >>> sz = s.zfill(10)
 >>> sz
 '0000000www'

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