Built-in Functions 1-10

Python3 built-in functions

Use command 'built-in_funtion.__doc__' to display the function help and usage.

*** therer is no '()' after the function name.

1. ', '. join(string)

      -->>> print(', '.join('123456'))

      '1,2,3,4,5, 6'

2. set()

      >>> set(['1', '2','1','7','9','7'])

              {'7', '9', '2', '1'}

       >>> set('1213111415326761718')

              {'3', '4', '7', '5', '2', '6', '8', '1'}

3. sum(num_list)

        >>> sum(['1','2','3','4','5','6'])

        Traceback (most recent call last):  File "", line 1, insum(['1','2','3','4','5','6'])TypeError: unsupported operand type(s) for +: 'int' and 'str'

      >>> sum([1,2,3,4,5,6]) ### list

      21

>>> sum((1,2,3,4,5,6))  ###tuple

21

      >>> sum([1],[3])

      Traceback (most recent call last):  File "", line 1, insum([1],[3])

       TypeError: can only concatenate list (not "int") to list

      >>> sum(1,2)

Traceback (most recent call last):  File "", line 1, insum(1,2)

   TypeError: 'int' object is not iterable

4. max()

   >>> max([1,2,3],[4,5,6])

            [4, 5, 6]

    >>> max([9],[1,2])

           [9]

    >>> max([9],[1,2,9])

           [9]

    >>> max([9],[10,2,9])

            [10, 2, 9]

    >>> max([9],[9,2,1])

           [9, 2, 1]

    >>> max('str1','str2')

             'str2'

    >>> max('1str','str2')

              'str2'

5. min()

         >>> min('1str','str2')

                '1str'

         >>> min([9],[9,2,1])

                 [9]

         >>> min([9],[1,2,9])

                [1, 2, 9]

          >>> min([1,2,3],[4,5,6])

                 [1, 2, 3]

6. id():  returns the 'identity' of an object, actually the memory address in memory

           >>> id(1)

             1850061888

          >>> id(2)

             1850061920

           >>> id(3)

             1850061952

            >>> id(0)

             1850061856

7. any(iterable): return 'True',  if any emlement of the iterable is true.

   >>> any(' ')

     True

   >>> any('')

      False

   >>> any('False')

      True

   >>> any('00000000000')

      True

   >>> any('  ')

      True

   >>> any('')

      False

   >>> any([])

      False

   >>> any([       ])

     False

   >>> any([''])

        False

>>> any(['      '])

     True

8. round(number, [,ndigits]): returns the number nearest to ndigits, or the nearest integer if ndigits is none.

          >>> round(2.51, 3)

             2.51

          >>> round(2.515, 3)

                    2.515

         >>> round(2.675, 2)

                2.67

       >>> round(2.615,2)

             2.62

         >>> round(2.515, 2)

                 2.52

         >>> round(2.51, 2)

              2.51

9. locals(): Update and return a dictionary representing the current local symbol table.

        >>> locals()

            {'__name__': '__main__', '__doc__': None, '__package__': None, '__loader__':, '__spec__': None, '__annotations__': {}, '__builtins__':, 'list1': ['1'], 'str2': '1-2-3-4-5-6-7-8-9', 'list_set': ['-', '1', '2', '3', '4', '5', '6', '7', '8', '9'], 'list_sort': ['-', '1', '2', '3', '4', '5', '6', '7', '8', '9']}

10. sorted(iterable) and list.sort()

1). sorted(iterable), not modify the iterable, but returns a new sorted list;

2). sort(), modify the list in-place, and return None.

3). sort() only accept list parameter, but sorted() accept any type of iterable parameter.

>>> list1=[1,5,8,2,3,9,4]

>>> list1

          [1, 5, 8, 2, 3, 9, 4]

>>> sorted(list1)

          [1, 2, 3, 4, 5, 8, 9]

>>> list1

          [1, 5, 8, 2, 3, 9, 4]

>>> list1.sort()  

           None

>>> list1

          [1, 2, 3, 4, 5, 8, 9]

>>> sorted({7: 'D', 2: 'B', 3: 'B', 9: 'E', 5: 'A', 6: 'Z'})

          [2, 3, 5, 6, 7, 9]

>>> sorted("This is a test string from Andrew".split(), key=str.lower)

         ['a', 'Andrew', 'from', 'is', 'string', 'test', 'This']