How do I declare an array in Python?
I can"t find any reference to arrays in the documentation.
variable = 
variable refers to an empty list*.
Of course this is an assignment, not a declaration. There"s no way to say in Python "this variable should never refer to anything other than a list", since Python is dynamically typed.
*The default built-in Python type is called a list, not an array. It is an ordered container of arbitrary length that can hold a heterogenous collection of objects (their types do not matter and can be freely mixed). This should not be confused with the
array module, which offers a type closer to the C
array type; the contents must be homogenous (all of the same type), but the length is still dynamic.
This is surprisingly complex topic in Python.
Check out usage examples:
# empty array arr =  # init with values (can contain mixed types) arr = [1, "eels"] # get item by index (can be negative to access end of array) arr = [1, 2, 3, 4, 5, 6] arr # 1 arr[-1] # 6 # get length length = len(arr) # supports append and insert arr.append(8) arr.insert(6, 7)
Under the hood Python"s
list is a wrapper for a real array which contains references to items. Also, underlying array is created with some extra space.
Consequences of this are:
arris same to
appendoperation is "for free" while some extra space
insertoperation is expensive
Check this awesome table of operations complexity.
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