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() 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