Built-in Functions¶

named sequence of code that does some specific task or a function
we'll learn how to define our own functions in User Defined Functions chapter
some built-in functions we've used so far: type( ), int( ), float( ), str( ), input( ), print( ), etc.
Python provides a list of built-in functions that are readily available for use:

https://docs.python.org/3/library/functions.html

below are examples of some built-in functions that may be useful to know

bin(x)¶

converts an integer number to a binary string prefixed with "0b".

In [1]:

bin(3)

Out[1]:

'0b11'

format(value, format_spec)¶

formats the give value using format spec

In [1]:

help(format)

Help on built-in function format in module builtins:

format(value, format_spec='', /)
    Return value.__format__(format_spec)
    
    format_spec defaults to the empty string.
    See the Format Specification Mini-Language section of help('FORMATTING') for
    details.

In [2]:

# If prefix "0b is desired or not, use either of the following ways
print(format(3, '#b'))
print(format(3, 'b'))

0b11
11

chr( uniCode )¶

returns the string representing a character whose Unicode code point is the integer uniCode
inverse of ord(character)

In [3]:

print(chr(65))
print(chr(97))
print(chr(8364))

A
a
€

globals() and locals()¶

globals() returns a dictionary representing the current global symbol table
locals() returns a dictionary representing the current local symbol table

In [4]:

globals()

Out[4]:

{'__name__': '__main__',
 '__doc__': 'Automatically created module for IPython interactive environment',
 '__package__': None,
 '__loader__': None,
 '__spec__': None,
 '__builtin__': <module 'builtins' (built-in)>,
 '__builtins__': <module 'builtins' (built-in)>,
 '_ih': ['',
  'bin(3)',
  '# If prefix "0b is desired or not, use either of the following ways\nprint(format(3, \'#b\'))\nprint(format(3, \'b\'))',
  'print(chr(65))\nprint(chr(97))\nprint(chr(8364))',
  'globals()'],
 '_oh': {1: '0b11'},
 '_dh': ['/Volumes/Storage/GoogleDrive/CMU/Python/thinkpythonnotebooks'],
 '_sh': <module 'IPython.core.shadowns' from '/Users/rbasnet/miniconda3/lib/python3.7/site-packages/IPython/core/shadowns.py'>,
 'In': ['',
  'bin(3)',
  '# If prefix "0b is desired or not, use either of the following ways\nprint(format(3, \'#b\'))\nprint(format(3, \'b\'))',
  'print(chr(65))\nprint(chr(97))\nprint(chr(8364))',
  'globals()'],
 'Out': {1: '0b11'},
 'get_ipython': <bound method InteractiveShell.get_ipython of <ipykernel.zmqshell.ZMQInteractiveShell object at 0x10f035278>>,
 'exit': <IPython.core.autocall.ZMQExitAutocall at 0x10fa42668>,
 'quit': <IPython.core.autocall.ZMQExitAutocall at 0x10fa42668>,
 '_': '0b11',
 '__': '',
 '___': '',
 '_i': 'print(chr(65))\nprint(chr(97))\nprint(chr(8364))',
 '_ii': '# If prefix "0b is desired or not, use either of the following ways\nprint(format(3, \'#b\'))\nprint(format(3, \'b\'))',
 '_iii': 'bin(3)',
 '_i1': 'bin(3)',
 '_1': '0b11',
 '_i2': '# If prefix "0b is desired or not, use either of the following ways\nprint(format(3, \'#b\'))\nprint(format(3, \'b\'))',
 '_i3': 'print(chr(65))\nprint(chr(97))\nprint(chr(8364))',
 '_i4': 'globals()'}

hex(x)¶

convert an integer number to a lowercase hexadecimal string prefixed with "0x"

In [5]:

print(hex(42))
print(hex(-42))

0x2a
-0x2a

In [2]:

# Other ways
print(format(255, '#x'))
print(format(255, 'x'))
print(format(255, 'X'))

0xff
ff
FF

oct(x)¶

return an octal string representation with "0o" prefix of a given integer x

In [7]:

print(oct(100))

0o144

In [8]:

print(format(10, '#o'))
print(format(10, 'o'))

0o12
12

ord(c)¶

return an integer representing the Unicode code of a given Unicode character

In [9]:

print(ord(' '))
print(ord('~'))

32
126

id(object)¶

return the 'identity' of an object
guaranteed unique integer and constant thoughout its lifetime

In [10]:

x = 10

In [11]:

id(x)

Out[11]:

4525196800

divmod(a, b)¶

given two non-complex numbers as arguments, return a pair of numbers as tuple consisting of their quotient and remainder using integer division

In [12]:

print(divmod(7, 3)) # return (quotient, remainder)
quotient, remainder = divmod(7, 3)
print(quotient, remainder)

(2, 1)
2 1

eval(expression, globals=None, locals=None)¶

the expression argument is parsed and evaluated as Python expression
syntax errors reported as exceptions

In [13]:

y = 2
print(eval('y**2'))
print(eval('y+2*3'))

4
8

max(iterable, ...) or max(arg1, arg2, ...)¶

returns the largest item in an iterable or the largest of two or more arguments

In [14]:

print('max=', max(100, 8.9, 999, 1000.5))

max= 1000.5

min(arg1, arg2, ...)¶

returns the smallest of the the arguments (arg1, arg2...)

In [15]:

print('min=', min(100, 8.9, 999, 1000.5))

min= 8.9

pow(base, exponent)¶

returns base to the power exponent

In [16]:

print('2 to the power 3 =', pow(2, 3))

2 to the power 3 = 8

print()¶

print(*object, sep=' ', end='\n', file=sys.stdout, flush=False)
print takes many arguments and print arbitrary number of values
demo some print examples with different argument values

In [17]:

print('hi', 'hello', sep='', end='')

hihello

In [19]:

print('hi', 'hello', sep=' ', end='')

hi hello

In [20]:

print('hi', 'hello', sep=' ', end='')
print('next line?')

hi hellonext line?

In [21]:

print('hi', 'hello', sep='\t', end='\n')
print('next line?')

hi	hello
next line?

In [ ]: