Presence of a certain file in the computer can be verified by two ways using Python code. One way is using isfile() function of os.path module. The function returns true if file at specified path exists, otherwise it returns false. >>> import os >>> os.path.isfile("d:\Package1\package1\fibo.py") True >>> os.path.isfile("d:/Package1/package1/fibo.py") True ... Read More

The built-in functions repr() and str() respectively call object.__repr__(self) and object.__str__(self) methods. First function computes official representation of the object, while second returns informal representation of the object. Result of both functions is same for integer object. >>> x = 1 >>> repr(x) '1' >>> str(x) '1' ... Read More

If L1 and L2 are list objects containing keys and respective values, following list comprehension syntax can be used to construct dictionary object. >>> L1 = ['a','b','c','d'] >>> L2 = [1,2,3,4] >>> d = {L1[k]:L2[k] for k in range(len(L1))} >>> d {'a': 1, 'b': 2, 'c': 3, 'd': 4}

You can create empty list object by giving no elements in square brackets in assignment statement. Empty list object is also created by list() built-in function without any arguments >>> L1 = [] >>> L1 [] >>> L1 = list() >>> L1 []

Python 3.0 was released in Dec. 2008. It was designed to rectify certain flaws in earlier version. The guiding principle of Python 3 was: "reduce feature duplication by removing old ways of doing things". Python 3.0 doesn’t provide backward compatibility. That means a Python program written using version 2.x syntax ... Read More

When used with strings, asterisk (*) is defined as repetition operator. It concatenates given string as many times as number followed by asterisk. >>> string = 'abcdefghij' >>> print (string*2) abcdefghijabcdefghij

When used with strings, plus (+) is defined as concatenation operator. It appends second string to the first string. >>> s1 = 'TutorialsPoint ' >>> s2 = 'Hyderabad' >>> print (s1+s2) TutorialsPoint Hyderabad

Any built-in data type converted into its string representation by str() function >>> str(10) '10' >>> str(11.11) '11.11' >>> str(3+4j) '(3+4j)' >>> str([1, 2, 3]) '[1, 2, 3]' >>> str((1, 2, 3)) '(1, 2, 3)' >>> str({1:11, 2:22, 3:33}) '{1: 11, 2: 22, 3: 33}' For a user ... Read More

Built-in dictionary class has update() method which merges elements of argument dictionary object with calling dictionary object. >>> a = {1:'a', 2:'b', 3:'c'} >>> b = {'x':1, 'y':2, 'z':3} >>> a.update(b) >>> a {1: 'a', 2: 'b', 3: 'c', 'x': 1, 'y': 2, 'z': 3} From Python 3.5 ... Read More

Dictionary is an unordered collection of key-value pairs. Each element is not identified by positional index. Moreover, the fact that key can’t be repeated, we simply use a new key and assign a value to it so that a new pair will be added to dictionary. >>> D1 = ... Read More