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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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