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

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Tuple in Python (2)

#python #tuple #index #function

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*Memo:

  • My post explains a tuple.
  • My post explains the tuple with slicing and copy.

index() can get the 1st index of the element matched to value from the tuple between [start, end), searching from the left to the right in the tuple as shown below:

*Memo:

  • The 1st argument is value(Required-Type:Any).
  • The 2nd argument is start(Optional-Default:0-Type:int):
    • It's a start index(inclusive).
    • Don't use start=.
  • The 3rd argument is end(Optional-Default:9223372036854775807-Type:int):
    • It's an end index(exclusive).
    • Don't use end=.
  • Error occurs if value doesn't exist. 
v = ('A', 'B', 'C', 'D', 'A', 'B', 'C', 'D') print(v.index('B')) # 1 print(v.index('B', 2)) # 5 print(v.index('B', 2, 6)) # 5 print(v.index('B', 2, 5)) # ValueError: tuple.index(x): x not in tuple
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count() can count the elements matched to value in the tuple as shown below:

*Memo:

  • The 1st argument is value(Required-Type:Any):
    • Don't use value=. 
v = ('A', 'B', 'C', 'A', 'B', 'B', 'A', 'B') print(v.count('A')) # 3 print(v.count('B')) # 4 print(v.count('C')) # 1 print(v.count('D')) # 0 print(v.count('a')) # 0
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sorted() can convert a tuple to a list, then sort the list, then the sorted list is converted to a tuple with tuple() as shown below:

*Memo:

  • The 1st argument is iterable(Required-Type:Iterable):
    • Don't use iterable=.
  • The 2nd argument is key(Optional-Default:None-Type:Callable or NoneType).
  • The 3rd argument is reverse(Optional-Default:False-Type:bool) to reverse the list.
  • sorted() creates a copy:
    • Be careful, sorted() does shallow copy instead of deep copy as my issue. 
v = (3, 5, -2, 1, -4) print(sorted(v)) print(sorted(v, key=None, reverse=False)) # [-4, -2, 1, 3, 5]  print(tuple(sorted(v))) # (-4, -2, 1, 3, 5)  print(tuple(sorted(v, reverse=True))) # (5, 3, 1, -2, -4)  print(tuple(sorted(v, key=abs))) # (1, -2, 3, -4, 5)  print(tuple(sorted(v, key=abs, reverse=True))) # (5, -4, 3, -2, 1)
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v = ("apple", "Banana", "Kiwi", "cherry") """ Case sensitive sort """ print(tuple(sorted(v))) # ('Banana', 'Kiwi', 'apple', 'cherry')  """ Case insensitive sort """ print(tuple(sorted(v, key=str.upper))) print(tuple(sorted(v, key=str.lower))) # ('apple', 'Banana', 'cherry', 'Kiwi')  """ Sort by the length of a word """ print(tuple(sorted(v, key=len))) # ('Kiwi', 'apple', 'Banana', 'cherry')
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reversed() can return the iterator which has the reversed elements of a tuple, then the iterator is converted to a tuple with tuple() as shown below:

*Memo:

  • The 1st argument is seq(Required-Type:Sequence):
    • Don't use seq=. 
v = (3, 5, -2, 1, -4) print(reversed(v)) # <reversed object at 0x000001F3B9D83C10>  print(tuple(reversed(v))) # (-4, 1, -2, 5, 3)
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v = ("apple", "Banana", "Kiwi", "cherry") print(tuple(reversed(v))) # ('cherry', 'Kiwi', 'Banana', 'apple')
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A tuple can be read by indexing as shown below. *Indexing can be done with one or more [index]:

<1D tuple>: 

v = ('A', 'B', 'C', 'D', 'E', 'F', 'G', 'H') v = 'A', 'B', 'C', 'D', 'E', 'F', 'G', 'H' print(v[0], v[1], v[2], v[3], v[4], v[5], v[6], v[7]) print(v[-8], v[-7], v[-6], v[-5], v[-4], v[-3], v[-2], v[-1]) # A B C D E F G H
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<2D tuple>: 

v = (('A', 'B', 'C', 'D'), ('E', 'F', 'G', 'H')) print(v[0], v[1]) print(v[-2], v[-1]) # ('A', 'B', 'C', 'D') ('E', 'F', 'G', 'H')  print(v[0][0], v[0][1], v[0][2], v[0][3], v[1][0], v[1][1], v[1][2], v[1][3]) print(v[-2][-4], v[-2][-3], v[-2][-2], v[-2][-1], v[-1][-4], v[-1][-3], v[-1][-2], v[-1][-1]) # A B C D E F G H
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<3D tuple>: 

v = ((('A', 'B'), ('C', 'D')), (('E', 'F'), ('G', 'H'))) print(v[0], v[1]) print(v[-2], v[-1]) # (('A', 'B'), ('C', 'D')) (('E', 'F'), ('G', 'H'))  print(v[0][0], v[0][1], v[1][0], v[1][1]) print(v[-2][-2], v[-2][-1], v[-1][-2], v[-1][-1]) # ('A', 'B') ('C', 'D') ('E', 'F') ('G', 'H')  print(v[0][0][0], v[0][0][1], v[0][1][0], v[0][1][1], v[1][0][0], v[1][0][1], v[1][1][0], v[1][1][1]) print(v[-2][-2][-2], v[-2][-2][-1], v[-2][-1][-2], v[-2][-1][-1], v[-1][-2][-2], v[-1][-2][-1], v[-1][-1][-2], v[-1][-1][-1]) # A B C D E F G H
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