java/c++ try throw catch

python try raise except

wtf :: python does not support inline assignment if(num=arg): not supported in python , but supported in c

every module is an object and they have a special property __name__

__name__ is the filename of the module , BUT IF THE PROGRAM IS CALLED AT FIRST WITHOUT IMPORTS ,

then __name__ is __main__

date types ::

Booleans

Numbers , integer -float-fraction-complex number

Strings

Bytes and byte arrays

Lists

Tuples

Sets

Dictionaries -- KEYS SHOULD BE IMMUTABLE

Booleans can be treated as numbers

True =1 , False = 0

"" ZERO VALUES ARE FALSE, NON ZERO ARE TRUE ""

True+True = 2

type()

and

isinstance()

int() will truncate, not round

/ => always floating division

// , for positive truncate for negative rounding down

fractions module

Lists :::

lists ['a','b','c']

slicing of list ,

lists can be added by .

adding two lists ,

append method append adds only 1 element to teh list , if a list is added , a list items stays as 1 element

insert method

extend mehtod all memebers are added

list.count('item')

list.index('item')

'item' in list

to remove from a list

del list['index']

list.remove('value')

list.pop()

list.pop(4)

list.shift()

lists can also be used as boolen , any list with at least an element is evaluated as True

''' PYTHON 3 , DAY 3 , PAGE NO:- 70 chapter :- TUPLES

In lists, square bracket is used , whereas in teh case of tuple , parenthesis are used ()

tuples are immutable

Tuples are same as Lists BUT THEY CANNOT BE CHANGED ,

TUPLES HAVE NO APPEND,POP,REMOVE,ADD METHODS LIKE THAT OF LISTS ,,

Tuples can be used for multiple assignments , if multiple values are returned from a function , then they can will

be saved as a tuple or individual parameters can be given to save them..

/// gotchaa , teh LHS variables should be equal to the number of values returned or should always be 1

SETS ARE ANOTHER DATA TYPES , their ordering is not determinable , union/intersection can be performed.

sets are implemented as class

sets can be created from list/tuple with set(<name>) method.

{} doesnt create empty set but creates an empty dictionary.

items can be added to the sets with add or update method,

add takes a single item to add to the set ,

update , takes a single SET to add its elements to the set.

items can be removed by the methods discard , remove , pop

REMEMBER , sets have no specific ordering

in set operations , symmetric_difference() , union() , intersection() are symmetric i.e.

a.symmetric_difference(b) equals b.symmetric_difference(a) and so on

DICTIONARY IS ANOHTER DATA TYPE

similar to set, but uses a key-value pair , list is UNORDERED SET OF KEY/VALUE PAIR , {}

### OS MODULE ###

os module takes care of operating system things.

os.path.join() used to construct os path names .. no need to worry of slashes

os.path.split() , splits a path into dir and file

os.path.splitext() , splits a filename into filename and extension, tuple returned

### GLOB MODULE ###

glob modules, to use wildcard characters for file/directory things

os.stat ,, shows metadata about the file ,

tiem.localtime , to convert unix time to local time

os.stat('file').st_size ,,, // returns the file size in bytes

os.path.realpath('fiel') // gives the absolute path for a file

os.path.relpath('file1') // prints the RELATIVE path

UTF - 32 || UTF - 16 || UTF - 8

*** ALL STRINGS ARE A SEQUENCE OF UNICODE CHARACTERS ***

sys.modules is a dictionary of all the imported modules , keys are the strings of module names and values are the module object

In an Item-Key , if the starting is number then it is treated as a number everything else is treated as a STRING

Bytes are bytes , characters are characters , strings are strings..

to declare a byte ,

byte1=b'abcd\xaa'

immutable byte cna be converted to mutable bytearray using bytearray() method

byte objects have decode method to convert to string,

string objects have encode method to return a byte

ROMAN NUMBERS :-

I = 1

V = 5

X = 10

L = 50

C = 100

D = 500

M = 1000

VARIABLE PASSING IN PYTHON, HOW ARE THEY PASSED , BY VALUE OR BY REFERENCE OR CALL-BY-OBJECT

REGULAR EXPRESSIONS AND CLOSURE/GENERATORS

re.sub('[abc]','o','Mark') is used to replace the 'a' in Mark by 'o' ,, this replaces all instance of a or b or c

so, maark => moork

PRINT LOCALS() , PRINT GLOBALS()

LIST OF PATTERNS \\\\ PYTHON

CLOSURES == USING VALUES OF OUTSIDE PARAMETERS INSIDE A DYNAMIC FUNCTION

**********

String is itself an iterator , giving out character on each iteration

and join() method takes an iterator as an argument

**********

Generators save space/memory , when using temporary lists just for a loop or sth, do use generators

itertools.permutations()

itertools.combinations()

itertools.groupby(seq,func) <= it works only if the sequence is already sorted

translate() method , takes a string and then a translation table

translation table consist of 1 byte:1byte to replace

eval() is EVILeval() is EVILeval() is EVILeval() is EVILeval() is EVILeval() is EVILeval() is EVILeval() is EVILeval() is EVILeval() is EVILeval() is EVILeval() is EVILeval() is EVILeval() is EVILeval() is EVILeval() is EVILeval() is EVIL