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Super Kai (Kazuya Ito)
Super Kai (Kazuya Ito)

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List in Python (4)

#python #list #brackets #function

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*Memos:

  • My post explains a list and the list with indexing.
  • My post explains the list with slicing and copy.
  • My post explains the useful functions for a list (1).
  • My post explains variable assignment.
  • My post explains shallow copy and deep copy.

You can use sort() to sort a list as shown below:
*Memos:

  • The 1st argument is key(Optional-Default:None) for a function.
  • The 2nd argument is reverse(Optional-Default:False) to reverse a list.
  • sort() doesn't create a copy different from sorted(). 
v = [-4, 1, 5, 3, -2] v.sort() print(v) # [-4, -2, 1, 3, 5]  v.sort(reverse=True) print(v) # [5, 3, 1, -2, -4]  v.sort(key=abs) print(v) # [1, -2, 3, -4, 5]  v.sort(key=abs, reverse=True) print(v) # [5, -4, 3, -2, 1]
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v = ["apple", "Banana", "Kiwi", "cherry"] # Case sensitive sort v.sort() print(v) # ['Banana', 'Kiwi', 'apple', 'cherry']  # Case insensitive sort v.sort(key=str.upper) v.sort(key=str.lower) print(v) # ['apple', 'Banana', 'cherry', 'Kiwi']  # Sort by the length of a word v.sort(key=len) print(v) # ['Kiwi', 'apple', 'Banana', 'cherry']
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You can use sorted() to sort a list as shown below:
*Memos:

  • The 1st argument is iterable(Required) for an iterable. *Don't use iterable=.
  • The 2nd argument is key(Optional-Default:None) for a function.
  • The 3rd argument is reverse(Optional-Default:False) to reverse a list.
  • sorted() creates a copy different from sort(). *Be careful, sorted() does shallow copy instead of deep copy as my issue. 
v = [-4, 1, 5, 3, -2] print(sorted(v)) # [-4, -2, 1, 3, 5]  print(sorted(v, reverse=True)) # [5, 3, 1, -2, -4]  print(sorted(v, key=abs)) # [1, -2, 3, -4, 5]  print(sorted(v, key=abs, reverse=True)) # [5, -4, 3, -2, 1]
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v = ["apple", "Banana", "Kiwi", "cherry"] # Case sensitive sort print(sorted(v)) # ['Banana', 'Kiwi', 'apple', 'cherry']  # Case insensitive sort print(sorted(v, key=str.upper)) print(sorted(v, key=str.lower)) # ['apple', 'Banana', 'cherry', 'Kiwi']  # Sort by the length of a word print(sorted(v, key=len)) # ['Kiwi', 'apple', 'Banana', 'cherry']
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You can use reverse() to reverse a list as shown below. *There are no arguments:

v = [-4, 1, 5, 3, -2] v.reverse() print(v) # [-2, 3, 5, 1, -4]  v = ["apple", "Banana", "Kiwi", "cherry"] v.reverse() print(v) # ['cherry', 'Kiwi', 'Banana', 'apple']
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You can use reversed() to reverse a list as shown below:
*Memos:

  • The 1st argument is seq(Required) for an iterable.
  • *Don't use seq=: 
v = [-4, 1, 5, 3, -2] print(list(reversed(v))) # [-2, 3, 5, 1, -4]  v = ["apple", "Banana", "Kiwi", "cherry"] print(list(reversed(v))) # ['cherry', 'Kiwi', 'Banana', 'apple']
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