Range functions in Python

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*Memo:

• My post explains a range (1).

index() can get the index of the element matched to value from the range as shown below:

*Memo:

• The 1st argument is value(Required-Type:Any).
• Error occurs if value doesn't exist.

v = range(5, 10)

print(*v)
# 5 6 7 8 9

print(v.index(7))  # 2
print(v.index(10)) # ValueError: 10 is not in range

count() can count the elements matched to value in the range as shown below:

*Memo:

• The 1st argument is value(Required-Type:Any):
  • Don't use value=.

v = range(5, 10)

print(*v)
# 5 6 7 8 9

print(v.count(7))  # 1
print(v.count(10)) # 0

sorted() can convert a range to a list, then sort the list 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 = range(-3, 3)

print(*v)
# -3 -2 -1 0 1 2

print(sorted(v))
print(sorted(v, key=None, reverse=False))
# [-3, -2, -1, 0, 1, 2]

print(sorted(v, reverse=True))
# [2, 1, 0, -1, -2, -3]

print(sorted(v, key=abs))
# [0, -1, 1, -2, 2, -3]

print(sorted(v, key=abs, reverse=True))
# [-3, -2, 2, -1, 1, 0]

reversed() can return the iterator which has the reversed elements of a range as shown below:

*Memo:

• The 1st argument is seq(Required-Type:Sequence):
  • Don't use seq=.

v = range(5)

print(*v)
# 0 1 2 3 4

print(reversed(v))
# <range_iterator object at 0x0000023D03BF5030>

print(*reversed(v))
# 4 3 2 1 0