Thursday, 26 December 2019

Python String -Part 3


Python rindex() method works same as the rfind() method except it throws error ValueError. This method throws an exception ValueError if the substring is not found. The syntax is given below.
Syntax
rindex(sub[, start[, end]]) 
Parameters
sub : substring to be searched.
start (optional) : starting index to start searching.
end (optional) : end index where to search stopped.
Return
It returns either index of substring or throws an exception ValueError.

Python String rindex() Method Example
A simple example is created first to see how to implement this method. This method returns index of the substring.
# Python rindex() method example 
# Variable declaration 
str = “It is technical tutorial” 
# calling function 
str2 = str.rindex(“t”) # No start and end is given 
# displaying result 
print(str2) 
Output:
18

Python String rindex() Method Example
This method accept parameters start and end index to search subtring from the substring. See the example below.
# Python rindex() method example 
# Variable declaration 
str = “It is technical tutorial” 
# calling function 
str2 = str.rindex(“t”) # No start and end is given 
# displaying result 
print(str2) 
str2 = str.rfind(“t”,5,15) # Start is end both are given 
print(str2) 
Output:
18
6

Python String rindex() Method Example
If the substring is not found in the string, it raises ValueError. See the example below.
# Python rindex() method example 
# Variable declaration 
str = “Hello C Language” 
# calling function 
str2 = str.rindex(“t”) # No start and end is given 
# displaying result 
print(str2) 
str2 = str.rfind(“t”,5,15) # Start is end both are given 
print(str2) 
Output:
ValueError: substring not found

Python rjust() method right justify the string and fill the remaining spaces with fillchars. This method returns a new string justified right and filled with fillchars.
Syntax
rjust(width[, fillchar]) 
Parameters
width : width of the given string.
fillchar : characters to fill the remaining space in the string. It is optional.
Return
It returns a right justified string.

Python String rjust() Method Example
# Python rjust() method example 
# Variable declaration 
str = 'Javatpoint' 
# Calling function 
str = str.rjust(15,”$”) 
# Displaying result 
print(str) 
Output:
$$$$$javapoint

Python rstrip() method removes all the trailing characters from the string. It means it removes all the specified characters from right side of the string. If we don't specify the parameter, It removes all the whitespaces from the string. This method returns a string value.
Syntax
rstrip([chars]) 
Parameters
chars: character to be removed from the string.
Return
It returns string.

Python String rstrip() Method Example
A simple example, does not take any parameter. It removes all the trailing whitespaces from the string.
# Python rstrip() method example 
# Variable declaration 
str = “Java and C# “ 
# Calling function 
str2 = str.rstrip() 
# Displaying result 
print(“Old string: “,str) 
print(“New String: “,str2) 
Output:
Old string:  Java and C#
New String:  Java and C#

Python rsplit() method seperates the string and returns a list. It splits from the right using seperator as a delimiter. If seperator is not specified, any whitespace string is a separator. This method does same as split() except splitting from the right which is described in detail below.
Note: if separator is not given, whitespace is treated as separator.
Syntax
rsplit(sep=None,maxsplit=-1) 
Parameters
sep: A string parameter acts as a seperator.
maxsplit: number of times split perfomed.
Return
It returns a comma separated list.

Python String rsplit() Method Example
This is a simple example to understand the usage of rsplit() method.
# Python rsplit() method example 
# Variable declaration 
str = “Java is a programming language” 
# Calling function 
str2 = str.rsplit() 
# Displaying result 
print(str2) 
Output:
['Java', 'is', 'a', 'programming', 'language']

Python String rsplit() Method Example
Let's pass a parameter separator to the method, see the example.
# Python rsplit() method example 
# Variable declaration 
str = “Java is a programming language” 
# Calling function 
str2 = str.rsplit('Java') 
# Displaying result 
print(str2) 
Output:
['', ' is a programming language']

Python split() method splits the string into a comma separated list. It separates string based on the separator delimiter. This method takes two parameters and both are optional. It is described below.
Syntax
split(sep=None, maxsplit=-1) 
Parameters
sep: A string parameter acts as a seperator.
maxsplit: Number of times split perfome.
Return
It returns a comma separated list.

Python String split() Method Example
This is a simple example to understand the usage of split() method. No parameter is given, by default whitespaces work as separator. See the example below.
# Python split() method example 
# Variable declaration 
str = “Java is a programming language” 
# Calling function 
str2 = str.split() 
# Displaying result 
print(str) 
print(str2) 
Output:
Java is a programming language
['Java', 'is', 'a', 'programming', 'language']

Python String split() Method Example
Let's pass a parameter separator to the method, now it will separate the string based on the separator. See the example below.
# Python split() method example 
# Variable declaration 
str = “Java is a programming language” 
# Calling function 
str2 = str.split('Java') 
# Displaying result 
print(str2)3 
Output:
['', ' is a programming language']

Python splitlines() method splits the string based on the lines. It breaks the string at line boundaries and returns a list of splitted strings. Line breakers can be a new line (\n), carriage return (\r) etc. A table of line breakers are given below which split the string.
This method splits on the given line boundaries.
Representation
Description
\n
Line Feed
\r
Carriage Return
\r\n
Carriage Return + Line Feed
\v or \x0b       
Line Tabulation
\f or \x0c
Form Feed
\x1c
File Separator
\x1d
Group Separator
\x1e
Record Separator
\x85
Next Line (C1 Control Code)
\u2028
Line Separator
\u2029
Paragraph Separator
Syntax
splitlines([keepends]) 
Parameters
keepends: It is a boolean value which can be either True or False. It is optional.
Return
It returns a comma separated list of lines.

Python String splitlines() Method Example
# Python splitlines() method example 
# Variable declaration 
str = “Java is a programming language” 
# Calling function 
str2 = str.splitlines() # returns a list having single element 
print(str) 
print(str2) 
str = “Java \n is a programming \r language” 
str2 = str.splitlines() # returns a list having splitted elements 
print(str2) 
Output:
Java is a programming language
['Java is a programming language']
['Java ', ' is a programming ', ' language']

Python String splitlines() Method Example
Passing True to the method which causes to include line breakers into the list of string. See the example below.
# Python splitlines() method example 
# Variable declaration 
str = “Java \n is a programming \r language” 
# Calling function 
str2 = str.splitlines(True) # returns a list having splitted elements 
print(str2) 
Output:
['Java \n', ' is a programming \r', ' language']

Python startswith() method returns either True or False. It returns True if the string starts with the prefix, otherwise False. It takes two parameters start and end. Start is a starting index from where searching starts and end index is where searching stops.
Syntax
startswith(prefix[, start[, end]]) 
Parameters
prefix : A string which is to be checked.
start : Start index from where searching starts.
end : End index till there searching performs.
Both start and end are optional parameters.
Return
It returns boolean value either True or False.

Python String startswith() Method Example
Let's first create a simple example which prints True if the string starts with the prefix.
# Python String startswith() method 
# Declaring variable 
str = “Hello Javatpoint” 
# Calling function 
str2 = str.startswith(“Hello”) 
# Displaying result 
print (str2) 
Output:
True

Python String startswith() Method Example
If the string does not start with prefix, the method returns False. See the example below
# Python String startswith() method 
# Declaring variable 
str = “Hello Javatpoint” 
# Calling function 
str2 = str.startswith(“Java”) # False 
# Displaying result 
print (str2) 
Output:
False

Python swapcase() method converts case of the string characters from uppercase to lowercase and vice versa. It does not require any parameter and returns a string after case conversion.
Syntax
swapcase() 
Parameters
No Parameter
Return
It returns a string.

Python String swapcase() Method Example
It is a simple example to convert uppercase to lowercase using the swapcase() method.
# Python String swapcase() method 
# Declaring variable 
str = “HELLO JAVATPOINT” 
# Calling function 
str2 = str.swapcase() 
# Displaying result 
print (str2) 
Output:
hello javatpoint

Python String swapcase() Method Example
This example describes conversion from lowercase to uppercase.
# Python String swapcase() method 
# Declaring variable 
str = “hello javatpoint” 
# Calling function 
str2 = str.swapcase() 
# Displaying result 
print (str2) 
Output:
HELLO JAVATPOINT

Python translate() method a string in which each character has been mapped through the given translation table. We can use maketrans() method to create a translation map from character-to-character mappings in different formats.
Syntax
translate(table) 
Parameters
table : A translation table.
Return
It returns a string.

Python String translate() Method Example
# Python translate() method  
# Declaring table and variables 
table = { 97 : 103, 111 : 112, 117 : None } 
str = “Hello javatpoint” 
# Calling function 
str2 = str.translate(table) 
# Displaying result 
print(str2) 
Output:
Hellp jgvgtppint

Python upper() method converts all the character to uppercase and returns a uppercase string.
Syntax
upper() 
Parameters
No parameters
Return
It returns a string.

Python String upper() Method Example
First see a simple example of upper() method. This method returns a uppercase string.
# Python upper() method  
# Declaring table and variables 
str = “Hello javatpoint” 
# Calling function 
str2 = str.upper() 
# Displaying result 
print(str2) 
Output:
HELLO JAVATPOINT

Python zfill() method fills the string at left with 0 digit to make a string of length width. It returns a string contains a sign prefix + or - before the 0 digit.
It returns original length string if the width is less than string length.
Syntax
zfill(width) 
Parameters
width : length of the string.
Return
It returns a string.

Python String zfill() Method Example
Let's see an example which has width greater than string length. It returns a new string containing 0 to the left and total length is equal to width.
# Python zfill(width) method  
# Declaring variables 
text = “Zfill Example” 
# Calling Function 
str2 = text.zfill(20) 
# Displaying result 
print(str2) 
Output:
0000000Zfill Example

Python String zfill() Method Example
This example describes the sign either + or - includes before the zero fills to the left of the string. See every value is filled after prefixing (+ or -) sign.

# Python zfill(width) method  
# Declaring variables 
val = “+100” 
val2 = “-200” 
val3 = “--Rohan--” 
# Calling Function 
str2 = val.zfill(10) 
str3 = val2.zfill(10) 
str4 = val3.zfill(10) 
# Displaying result 
print(str2) 
print(str3) 
print(str4) 
Output:
+000000100
-000000200
-0-Rohan—

Python Title() method is the Python String Method which is used to convert the first character in each word to Uppercase and remaining characters to Lowercase in string and returns new string.
Syntax:
str.Title()
parameters:str is a valid string which we need to convert.
return: This function returns a string which has first letter in each word is uppercase and all remaining letters are lowercase.

# Python Title() Method Example
str1 = 'geeKs foR geEks'
str2 = str1.title()
print ('First Output after Title() method is = ', str2 )
# observe the original string
print ('Converted String is = ', str1.title() )
print ('Original String is = ', str1 )
# Performing title() function directly
str3 = 'ASIPU pawan kuMAr'.title()
print ('Second Output after Title() method is = ', str3 )
str4 = 'stutya kUMari sHAW'.title()
print ('Third Output after Title() method is = ', str4 )
str5 = '6041'.title()
print ('Fourth Output after Title() method is = ', str5 )
Output:
First Output after Title() method is =  Geeks For Geeks
Converted String is =  Geeks For Geeks
Original String is =  geeKs foR geEks
Second Output after Title() method is =  Asipu Pawan Kumar
Third Output after Title() method is =  Stutya Kumari Shaw
Fourth Output after Title() method is =  6041

Python rpartition() method splits the string at the last occurrence of seperator substring.It splits the string from the last occurrence of parameter and returns a tuple. The tuple contains the three parts before the separator, the separator itself, and the part after the separator.
It returns an empty tuple having seperator only, if the seperator not found.
The method Syntax is given below.
Syntax
rpartition(sep) 
Parameters
sep: A string parameter which separates the string.
Return
It returns a tuple, A 3-Tuple.

Python String rpartition() Method Example
Let's see a simple use of partition method in various scenario.
# Python rpartition() method example 
# Variable declaration 
str = “Java is a programming language” 
# Calling function 
str2 = str.rpartition(“is”) 
# Displaying result 
print(str2) 
# seperator is at begining 
str2 = str.rpartition(“Java”) 
print(str2) 
# seperator at ent 
str2 = str.rpartition(“language”) 
print(str2) 
# when seperater is a substring 
str2 = str.rpartition(“av”) 
print(str2) 
Output:
('Java ', 'is', ' a programming language'')
('', 'Java', ' is a programming language')
('Java is a programming ', 'language', '')
('J', 'av', 'a is a programming language')

Python strip() method returns a copy of the string with both leading and trailing characters removed (based on the string argument passed).
The strip() removes characters from both left and right based on the argument (a string specifying the set of characters to be removed).
The syntax of strip() is:
string.strip([chars])
Parameters
chars (optional) - a string specifying the set of characters to be removed.
If the chars argument is not provided, all leading and trailing whitespaces are removed from the string.

Return Value from strip()
The strip() returns a copy of the string with both leading and trailing characters stripped.
When the combination of characters in the chars argument mismatches the character of the string in the left, it stops removing the leading characters.
Similarly, when the combination of characters in the chars argument mismatches the character of the string in the right, it stops removing the trailing characters.
Example:
string = ' xoxo love xoxo   '
# Leading whitepsace are removed
print(string.strip())
print(string.strip(' xoxoe'))
# Argument doesn't contain space
# No characters are removed.
print(string.strip('sti'))
string = 'android is awesome'
print(string.strip('an'))
Output:
xoxo love xoxo
lov
 xoxo love xoxo  
droid is awesome

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