Python Essentials: 60 Frequently Used Built-in Functions and Techniques

This guide compiles 60 commonly used Python snippets that demonstrate essential built-in functions and techniques for everyday programming.

Numeric utilities include absolute value ( abs(-6)), base conversions ( bin(10), oct(9), hex(15)), integer-ASCII mapping ( chr(65), ord('A')), truth-value checks ( all([1,2,3]), any([0,1])), boolean casting ( bool([])), complex numbers ( complex(1,2)), division with remainder ( divmod(10,3)), type casting ( float(3), int('12',16)), exponentiation with modulus ( pow(3,2,4)), rounding ( round(10.0222222,3)), and chained comparisons ( 1 < i < 3).

String handling covers conversion to bytes ( bytes(s,encoding='utf-8')), generic string conversion ( str(i)), dynamic code execution ( compile(s,"<string>","exec"), exec(r)), evaluation ( eval('1 + 3 +5')), and formatting ( "i am {0},age{1}".format("tom",18)).

Function utilities demonstrate sorting ( sorted(a,reverse=True)), custom key sorting, summation with start value ( sum(a,10)), nonlocal variable updates, global declarations, swapping ( def swap(a,b): return b,a), function objects list indexing ( [f,g][1]()), reverse range generation ( list(range(10,-1,-1))), and parameter patterns ( def f(a,*b,c=10,**d): ...).

Data structures show dictionary creation ( dict(a='a',b='b'), dict(zip(['a','b'],[1,2]))), frozen sets ( frozenset([1,1,3,2,3])), mutable sets ( set(a)), slice objects ( slice(0,5,2)), tuples ( tuple(i_am_list)), and reusable slice objects for indexing.

Classes and objects illustrate callable checks ( callable(str)), custom __repr__, class methods, attribute access ( getattr(obj,'name')), dynamic attribute deletion ( delattr(obj,'id')), type inspection ( type(obj)), metaclass concepts, and property definitions using @property decorators.

Useful tools include enumeration ( enumerate(seq,1)), memory size measurement ( sys.getsizeof(dict)), filtering ( filter(lambda x: x>10, seq)), hashing ( hash(obj)), help documentation ( help(obj)), user input ( input()), file I/O ( open('a.txt','r')), range creation, reversed iteration ( reversed([1,2,3])), aggregation with zip, chain operations, and JSON serialization of custom objects ( json.dump([obj1,obj2], f, default=lambda o: o.__dict__)).

The article concludes with a QR code offering free Python learning resources.