Python - String Methods (Reversed)

Question 1

string.capitalize()

Answer 1

Return - string
Args - none
___________
returns a string with first letter capitalized and all other characters lowercased. It doesn’t modify the original string

Question 2

string.center()

Answer 2

Return - string
Args - (width, ‘some char’)
___________
returns a string padded on both sides with specified char. It doesn’t modify the original string. If no second arg provided then blank spaces are default.

Question 3

string.casefold()

Answer 3

Return - string
Args - none
___________
removes all case distinctions present in a string. It is used for caseless matching, i.e. ignores cases when comparing. For example, German lowercase letter ß is equivalent to ss. However, since ß is already lowercase, lower() method does nothing to it. But, casefold() converts it to ss.

Question 4

string.count()

Answer 4

Return - int
Args - (substring, start, end)
___________
searches the substring in the given string and returns how many times the substring is present in it. It also takes optional parameters start and end to specify the starting and ending positions in the string respectively.

Question 5

string.endswith()

Answer 5

Return - True/False
Args - (suffix, start, end)
___________
returns True if a string ends with the specified suffix. If not, it returns False.

Question 6

string.expandtabs()

Answer 6

Return - copy of string
Args - (tab size)
___________
returns a copy of string with all tab characters ‘\t’ replaced with whitespace characters until the next multiple of tabsize parameter.

Question 7

string.encode()

Answer 7

Return - byte string
Args - (encoding=’UTF-8’,errors=’strict’)
___________
By default, encode() method doesn’t require any parameters.

It returns utf-8 encoded version of the string. In case of failure, it raises a UnicodeDecodeError exception.

However, it takes two parameters:

1) encoding - the encoding type a string has to be encoded to
2) errors - response when encoding fails.
There are six types of error response:

strict - default response which raises a UnicodeDecodeError exception on failure

ignore - ignores the unencodable unicode from the result

replace - replaces the unencodable unicode to a question mark ?

xmlcharrefreplace - inserts XML character reference instead of unencodable unicode

backslashreplace - inserts a \uNNNN espace sequence instead of unencodable unicode

namereplace - inserts a \N{…} escape sequence instead of unencodable unicode

Question 8

string.find()

Answer 8

Return - index
Args - (substring, start, end)
___________
returns the index of first occurrence of the substring (if found). If not found, it returns -1. Start and End args are optional.

Question 9

“blah blah {0} blah blah {1:5.3f}”.format(‘input0’, ‘input2’)

Answer 9

Return - formatted string with inputs
Args - (first input, second input, …)
___________
reads the type of arguments passed to it and formats it according to the format codes defined in the string. First value in given string is the argument it references and will substitute for in the given parameters, first number after colon is the number of total spaces allocated to the entire inputted argument, number after decimal with the f is the number of decimal places after the input number

Question 10

string.index()

Answer 10

Return - index
Args - (substring, start, end)
___________
returns the index of a substring inside the string (if found). If the substring is not found, it raises an exception

Question 11

string.isalnum()

Answer 11

Return - True/False
Args - none
___________
returns True if all characters in the string are alphanumeric (either alphabets or numbers). If not, it returns False

Question 12

string.isalpha()

Answer 12

Return - True/False
Args - none
___________
returns True if all characters in the string are alphabets. If not, it returns False.

Question 13

string.isdecimal()

Answer 13

Return - True/False
Args - none
___________
returns True if all characters in a string are decimal characters. If not, it returns False.

Question 14

string.isdigit()

Answer 14

Return - True/False
Args - none
___________
returns True if all characters in a string are digits. If not, it returns False

Question 15

string.isidentifier()

Answer 15

Return - True/False
Args - none
___________
returns True if the string is a valid identifier in Python. If not, it returns False.

Question 16

string.islower()

Answer 16

Return - True/False
Args - none
___________
returns True if all alphabets in a string are lowercase alphabets. If the string contains at least one uppercase alphabet, it returns False.

Question 17

string.isnumeric()

Answer 17

Return - True/False
Args - none
___________
returns True if all characters in a string are numeric characters. If not, it returns False.

Question 18

string.isprintable()

Answer 18

Return - True/False
Args - none
___________
returns True if all characters in the string are printable or the string is empty. If not, it returns False.

Characters that occupies printing space on the screen are known as printable characters. For example:

letters and symbols
digits
punctuation
whitespace

Question 19

string.isspace()

Answer 19

Return - True/False
Args - none
___________
returns True if there are only whitespace characters in the string. If not, it return False.

Characters that are used for spacing are called whitespace characters. For example: tabs, spaces, newline etc.

Question 20

string.istitle()

Answer 20

Return - True/False
Args - none
___________
returns True if the string is a titlecased string. If not, it returns False.

Question 21

string.isupper()

Answer 21

Return - True/False
Args - none
___________
returns whether or not all characters in a string are uppercased or not.

Question 22

separator = ‘, ‘

separator.join(someIterable)

Answer 22

Return - concatenated string
Args - (iterable)
___________
provides a flexible way to concatenate string. It concatenates each element of an iterable (such as list, string and tuple) to the string and returns the concatenated string

Question 23

string.ljust() and rjust()

Answer 23

Return - string
Args - (width, ‘optional fill char’)
___________
returns a left or right-justified string of a given minimum width.

Question 24

string.lower()

Answer 24

Return - lowercased version of string
Args - none
___________
converts all uppercase characters in a string into lowercase characters and returns it.

Question 25

string.upper()

Answer 25

Return - uppercased version of string
Args - none
___________
converts all lowercase characters in a string into uppercase characters and returns it.

Question 26

string.swapcase()

Answer 26

Return - opposite-cased version of string
Args - none
___________
converts all uppercase characters to lowercase and all lowercase characters to uppercase characters of the given string, and returns it.

Question 27

string.lstrip() and rstrip()

Answer 27

Return - stripped string
Args - (‘char’) or ([char1, char2, …])
___________
removes characters from the leading left or right based on the argument (a string specifying the set of characters to be removed).

Question 28

string.strip()

Answer 28

Return - stripped string
Args - (‘char’) or ([char1, char2, …])
___________
removes characters from both left and right based on the argument (a string specifying the set of characters to be removed).

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.

Question 29

string.partition()

Answer 29

Return - 3-tuple
Args - (separator)
___________
splits the string at the first occurrence of the argument string and returns a tuple containing the part the before separator, argument string and the part after the separator.

The partition method returns a 3-tuple containing:

the part before the separator, separator parameter, and the part after the separator if the separator parameter is found in the string
string itself and two empty strings if the separator parameter is not found

Question 30

string.maketrans()

Answer 30

Return - dict
Args - (x, y, z)
___________
returns a mapping table for translation usable for translate() method.

In simple terms, the maketrans() method is a static method that creates a one to one mapping of a character to its translation/replacement.

It creates a Unicode representation of each character for translation.

This translation mapping is then used for replacing a character to its mapped character when used in translate() method.

3 parameters:

x - If only one argument is supplied, it must be a dictionary.
The dictionary should contain 1-to-1 mapping from a single character string to its translation OR a unicode number (97 for ‘a’) to its translation.
y - If two arguments are passed, it must be two strings with equal length.
Each character in the first string is a replacement to its corresponding index in the second string.
z - If three arguments are passed, each character in the third argument is mapped to None.

Question 31

string.rpartition()

Answer 31

Return - 3-tuple
Args - (separator)
___________
splits the string at the last occurrence of the argument string and returns a tuple containing the part the before separator, argument string and the part after the separator.

The rpartition method returns a 3-tuple containing:

the part before the separator, separator parameter, and the part after the separator if the separator parameter is found in the string
two empy strings, followed by the string itself if the separator parameter is not found

Question 32

string.translate()

Answer 32

Return - string
Args - (table)
___________
returns a string where each character is mapped to its corresponding character in the translation table.

The translate() method takes a single parameter:

table - a translation table containing the mapping between two characters; usually created by maketrans()

Question 33

string.replace()

Answer 33

Return - string
Args - (old substring, new substring, number of times you want it replaced with)
___________
returns a copy of the string where all occurrences of a substring is replaced with another substring.

Question 34

string.rfind()

Answer 34

Return - index
Args - (substring, start, end)
___________
returns the highest index of the substring (if found). If not found, it returns -1.

The rfind() method takes maximum of three parameters:

sub - It’s the substring to be searched in the str string.
start and end (optional) - substring is searched within str[start:end]

Question 35

string.rindex()

Answer 35

Return - index
Args - (substring, start, end)
___________
returns the highest index of the substring inside the string (if found). If the substring is not found, it raises an exception.

The rindex() method takes three parameters:

sub - substring to be searched in the str string.
start and end(optional) - substring is searched within str[start:end]

Question 36

string.split()

Answer 36

Return - list of strings
Args - (separator, max # of splits desired)
___________
breaks up a string at the specified separator and returns a list of strings.

The split() method takes maximum of 2 parameters:

separator (optional)- The is a delimiter. The string splits at the specified separator.

If the separator is not specified, any whitespace (space, newline etc.) string is a separator.

maxsplit (optional) - The maxsplit defines the maximum number of splits.

The default value of maxsplit is -1, meaning, no limit on the number of splits.

Question 37

string.rsplit()

Answer 37

Return - list of strings
Args - (separator, max # of splits desired)
___________
splits string from the right at the specified separator and returns a list of strings.

The rsplit() method takes maximum of 2 parameters:

separator (optional)- The is a delimiter. The rsplit() method splits string starting from the right at the specified separator.

If the separator is not specified, any whitespace (space, newline etc.) string is a separator.

maxsplit (optional) - The maxsplit defines the maximum number of splits.

The default value of maxsplit is -1, meaning, no limit on the number of splits.

Question 38

string.splitlines()

Answer 38

Return - list of strings
Args - (optional keepends=True)
___________
splits the string at line breaks and returns a list of lines in the string.

The splitlines() takes maximum of 1 parameter.

keepends (optional) - If keepends is provided and True, line breaks are also included in items of the list.

Question 39

string.startswith()

Answer 39

Return - boolean
Args - (prefix, start, end)
___________
returns True if a string starts with the specified prefix(string). If not, it returns False.

The startswith() method takes maximum of three parameters:

prefix - String or tuple of strings to be checked
start (optional) - Beginning position where prefix is to be checked within the string.
end (optional) - Ending position where prefix is to be checked within the string.

Question 40

string.title()

Answer 40

Return - string
Args - none
___________
returns a string with first letter of each word capitalized; a title cased string.

Question 41

string.zfill()

Answer 41

Return - string
Args - (width)
___________
returns a copy of the string with ‘0’ characters padded to the left.

The width specifies the length of the returned string from zfill() with ‘0’ digits filled to the left.

Question 42

string.format_map()

Answer 42

Return - string
Args - ( dictionary of mapped key-values )
___________
similar to str.format(mapping) except that str.format(mapping) creates a new dictionary whereas str.format_map(mapping) doesn’t.

Question 43

string.any()

Answer 43

Return - boolean
Args - ( iterable )
___________
returns True if any element of an iterable is True. If not, any() returns False. If empty, returns returns False.

Question 44

string.all()

Answer 44

Return - boolean
Args - ( iterable )
___________
returns True when all elements in the given iterable are true. If not, it returns False. If empty, returns True.

Question 45

string.ascii()

Answer 45

Return - string
Args - ( object like string, list, etc )
___________
returns a string containing a printable representation of an object. It escapes the non-ASCII characters in the string using \x, \u or \U escapes.

Question 46

string.bool()

Answer 46

Return - boolean
Args - ( value )
___________
converts a value to Boolean (True or False) using the standard truth testing procedure.

The following values are considered false in Python:

None

False

Zero of any numeric type. For example, 0, 0.0, 0j

Empty sequence. For example, (), [], ‘’.

Empty mapping. For example, {}

objects of Classes which has __bool__() or __len()__ method which returns 0 or False

All other values except these values are considered true.

Question 47

string.complex()

Answer 47

Return - complex #
Args - ( string with real and imag parts )
___________
returns a complex number when real and imaginary parts are provided, or it converts a string to a complex number.

The string passed to the complex() should be in the form real+imagj or real+imagJ

In general, the complex() method takes two parameters:

real - real part. If real is omitted, it defaults to 0.
imag - imaginary part. If imag is omitted, it default to 0.
If the first parameter passed to this method is a string, it will be interpreted as a complex number. In this case, second parameter shouldn’t be passed.

Question 48

enumerate()

Answer 48

Return - tuples of (counter, iterable)
Args - ( iterable, optional start value )
___________
adds counter to an iterable and returns it (the enumerate object).

The enumerate() method takes two parameters:

iterable - a sequence, an iterator, or objects that supports iteration
start (optional) - enumerate() starts counting from this number. If start is omitted, 0 is taken as start.

Question 49

filter()

Answer 49

Return - an iteratOR
Args - ( function, iterable )
___________
constructs an iterator from elements of an iterable for which a function returns true.

filters the given iterable with the help of a function that tests each element in the iterable to be true or not.

Question 50

float()

Answer 50

Return - float
Args - ( optional string to convert )
___________
returns a floating point number from a number or a string.

The float() method takes a single parameter:

x (Optional) - number or string that needs to be converted to floating point number
If it’s a string, the string should contain decimal points

Question 51

input()

Answer 51

Return - string
Args - ( optional string to prompt user )
___________
reads a line from input, converts into a string and returns it.

Question 52

int()

Answer 52

Return - int object
Args - ( string to convert, optional base )
___________
returns an integer object from any number or string.

he int() method returns:

an integer object from the given number or string, treats default base as 10
(No parameters) returns 0
(If base given) treats the string in the given base (0, 2, 8, 10, 16)

Question 53

iter()

Answer 53

Return - iter object
Args - ( set/tuple object to turn into iter, optional sentinel value to represent end of sequence )
___________
creates an object which can be iterated one element at a time.

These objects are useful when coupled with loops like for loop, while loop.

Question 54

len()

Answer 54

Return - length
Args - ( string/bytes/tuple/list/range )
___________
returns the number of items (length) in an object.

Question 55

max()

Answer 55

Return - largest element
Args - ( iterable, optional second iterable to compare against one-by-one, etc )
___________
returns the largest element in an iterable or largest of two or more parameters.

Question 56

min()

Answer 56

Return - smallest element
Args - ( iterable, optional second iterable to compare against one-by-one, etc )
___________
returns the smallest element in an iterable or smallest of two or more parameters.

Question 57

map()

Answer 57

Return - map object
Args - ( function, iterable )
___________
applies a given function to each item of an iterable (list, tuple etc.) and returns a map of the results.

this map can then be wrapped by the list() method to create a list of the results, or wrapped by a set() method, etc

Question 58

ord()

Answer 58

Return - int representing unicode
Args - ( char )
___________
returns an integer representing Unicode code point for the given Unicode character.

Question 59

reversed()

Answer 59

Return - sequence
Args - ( tuple/string/list/range )
___________
returns the reversed iterator of the given sequence.

Question 60

slice()

Answer 60

Return - slice object
Args - ( optional start, stop, optional step )
___________
creates a slice object representing the set of indices specified by range(start, stop, step).

The slice object is used to slice a given sequence (string, bytes, tuple, list or range) or any object which supports sequence protocol (implements __getitem__() and __len__() method).

Question 61

sorted()

Answer 61

Return - sorted list
Args - ( iterable, optional reverse=True, optional function that serves as a key to the sort comparison )
___________
returns a sorted list from the given iterable.

Question 62

sum()

Answer 62

Return - sum
Args - ( iterable, optional start value )
___________
adds the items of an iterable and returns the sum.

Question 63

zip()

Answer 63

Return - iterator of tuples
Args - ( 1st iterable, 2nd iterable, etc)
___________
take iterables (can be zero or more), makes iterator that aggregates elements based on the iterables passed, and returns an iterator of tuples.