4.4. Sequence Comparison¶
tuple- fast and memory efficientlist- extensible and flexibleset- very fast lookup
4.4.1. Tuple¶
Immutable - cannot add, modify or remove items
Stores elements of any type
Keeps order of inserting elements
Possible to getitem and slice
Elements can duplicate
One contingent block of data in memory
4.4.2. List¶
Mutable - can add, remove, and modify items
Stores elements of any type
Keeps order of inserting elements
Possible to getitem and slice
Elements can duplicate
Implemented in memory as list of references to objects
Objects are scattered in memory
4.4.3. Set¶
Mutable - can add, remove, and modify items
Stores only hashable elements (int, float, bool, None, str, tuple)
Does not keep order of inserting elements
It is not possible to getitem and slice
Elements cannot duplicate
Set is unordered data structure and do not record element position or insertion
4.4.4. Memory Footprint¶
>>> from sys import getsizeof
>>>
>>>
>>> getsizeof( (1,2,3) )
64
>>>
>>> getsizeof( [1,2,3] )
120
>>>
>>> getsizeof( {1,2,3} )
216
4.4.5. Memory¶
Figure 4.3. Memory representation for list and tuple¶
4.4.6. Performance¶
O(n)- lookup (contains) in list and tupleO(1)- lookup (contains) in set
>>> %%timeit -r 10_000 -n 10_000
... 0 in (1, 2, 3)
...
48 ns ± 6.57 ns per loop (mean ± std. dev. of 10000 runs, 10,000 loops each)
>>>
>>> %%timeit -r 10_000 -n 10_000
... 0 in [1, 2, 3]
...
49.1 ns ± 6.39 ns per loop (mean ± std. dev. of 10000 runs, 10,000 loops each)
>>>
>>> %%timeit -r 10_000 -n 10_000
... 0 in {1, 2, 3}
...
27.2 ns ± 3.97 ns per loop (mean ± std. dev. of 10000 runs, 10,000 loops each)
>>> %%timeit -r 10_000 -n 10_000
... 0 in (1, 2, 3, 4, 5, 6, 7, 8, 9)
...
99.2 ns ± 12.2 ns per loop (mean ± std. dev. of 10000 runs, 10,000 loops each)
>>>
>>> %%timeit -r 10_000 -n 10_000
... 0 in [1, 2, 3, 4, 5, 6, 7, 8, 9]
...
98.5 ns ± 12.2 ns per loop (mean ± std. dev. of 10000 runs, 10,000 loops each)
>>>
>>> %%timeit -r 10_000 -n 10_000
... 0 in {1, 2, 3, 4, 5, 6, 7, 8, 9}
...
27.8 ns ± 4.21 ns per loop (mean ± std. dev. of 10000 runs, 10,000 loops each)