list

• list copy

• reverse list

• cast format (str -> int)

• zip two lists

• list mathematical

list copy

inspired by How to clone or copy a list? in stackoverflow

clone_list = sample_list.copy()

• or

  clone_list = sample_list[:]

• or

  clone_list = list(sample_list)

• or

  import copy
  clone_list = copy.copy(sample_list)

• or

  import copy
  clone_list = copy.deepcopy(sample_list)

• example:

  >>> id(x)
  4505979072
  >>> k = x
  >>> id(k)
  4505979072
  
  >>> k = x.copy()
  >>> id(k)
  4445208000
  >>> k = x[:]
  >>> id(k)
  4505977632
  >>> import copy
  >>> k = copy.copy(x)
  >>> id(k)
  4505754352
  >>> k = copy.deepcopy(x)
  >>> id(k)
  4505978352
  >>> k = x[:]
  >>> id(k)
  4506260896
  >>> k = copy.deepcopy(x)
  >>> id(k)
  4506261136

reverse list

sample_list[::-1]

• example:

  >>> ['1', '2', '3', '4', '5'][::-1]
  ['5', '4', '3', '2', '1']

cast format (str -> int)

list( map(int, sample_list) )

• example:

  >>> print( list( map(int, ['2', '8', '4', '127', 'HKD'][:3][::-1] ) ) )
  [4, 8, 2]

zip two lists

>> from itertools import zip_longest
>>> x = ['1', '2', '3', '4']
>>> y = ['one', 'two', 'three', 'four']
>>> for i, j in zip_longest( x, y ):
  print(i, j)

1 one
2 two
3 three
4 four

• or zip to a map

  >>> x = ['1', '2', '3', '4']
  >>> y = ['one', 'two', 'three', 'four']
  >>> print( {key: value for key, value in zip_longest(x, y)} )
  {'1': 'one', '2': 'two', '3': 'three', '4': 'four'}

list mathematical

• sum

  >>> n = ['1', '2', '3', '4']
  >>> print( sum( list( map(int, n) ) ) )
  10

• multiplication