def bucket_sort(array: Array, **kwargs) -> Array:
"""
Performs bucket sort on the given array.
Parameters
==========
array: Array
The array which is to be sorted.
start: int
The starting index of the portion
which is to be sorted.
Optional, by default 0
end: int
The ending index of the portion which
is to be sorted.
Optional, by default the index
of the last position filled.
Returns
=======
output: Array
The sorted array.
Examples
========
>>> from pydatastructs import DynamicOneDimensionalArray as DODA, bucket_sort
>>> arr = DODA(int, [5, 78, 1, 0])
>>> out = bucket_sort(arr)
>>> str(out)
"['0', '1', '5', '78']"
>>> arr.delete(2)
>>> out = bucket_sort(arr)
>>> str(out)
"['0', '1', '78']"
References
==========
.. [1] https://en.wikipedia.org/wiki/Bucket_sort
Note
====
This function does not support custom comparators as is the case with
other sorting functions in this file.
The ouput array doesn't contain any `None` value.
"""
start = kwargs.get('start', 0)
end = kwargs.get('end', len(array) - 1)
#Find maximum value in the list and use length of the list to determine which value in the list goes into which bucket
max_value = None
for i in range(start, end + 1):
if array[i] is not None:
max_value = array[i]
count = 0
for i in range(start, end + 1):
if array[i] is not None:
count += 1
if array[i] > max_value:
max_value = array[i]
number_of_null_values = end - start + 1 - count
size = max_value // count
# Create n empty buckets where n is equal to the length of the input list
buckets_list = [[] for _ in range(count)]
# Put list elements into different buckets based on the size
for i in range(start, end + 1):
if array[i] is not None:
j = array[i] // size
if j is not count:
buckets_list[j].append(array[i])
else:
buckets_list[count - 1].append(array[i])
# Sort elements within the buckets using Insertion Sort
for z in range(count):
_bucket_sort_helper(buckets_list[z])
# Concatenate buckets with sorted elements into a single array
sorted_list = []
for x in range(count):
sorted_list.extend(buckets_list[x])
for i in range(end, end - number_of_null_values, -1):
array[i] = None
for i in range(start, end - number_of_null_values + 1):
array[i] = sorted_list[i - start]
if _check_type(array, DynamicArray):
array._modify(force=True)
return array
def cocktail_shaker_sort(array: Array, **kwargs) -> Array:
"""
Performs cocktail sort on the given array.
Parameters
==========
array: Array
The array which is to be sorted.
start: int
The starting index of the portion
which is to be sorted.
Optional, by default 0
end: int
The ending index of the portion which
is to be sorted.
Optional, by default the index
of the last position filled.
comp: lambda/function
The comparator which is to be used
for sorting. If the function returns
False then only swapping is performed.
Optional, by default, less than or
equal to is used for comparing two
values.
Returns
=======
output: Array
The sorted array.
Examples
========
>>> from pydatastructs import OneDimensionalArray as ODA, cocktail_shaker_sort
>>> arr = ODA(int, [5, 78, 1, 0])
>>> out = cocktail_shaker_sort(arr)
>>> str(out)
'[0, 1, 5, 78]'
>>> arr = ODA(int, [21, 37, 5])
>>> out = cocktail_shaker_sort(arr)
>>> str(out)
'[5, 21, 37]'
References
==========
.. [1] https://en.wikipedia.org/wiki/Cocktail_shaker_sort
"""
def swap(i, j):
array[i], array[j] = array[j], array[i]
lower = kwargs.get('start', 0)
upper = kwargs.get('end', len(array) - 1)
comp = kwargs.get("comp", lambda u, v: u <= v)
swapping = False
while (not swapping and upper - lower >= 1):
swapping = True
for j in range(lower, upper):
if _comp(array[j], array[j + 1], comp) is False:
swap(j + 1, j)
swapping = False
upper = upper - 1
for j in range(upper, lower, -1):
if _comp(array[j - 1], array[j], comp) is False:
swap(j, j - 1)
swapping = False
lower = lower + 1
if _check_type(array, DynamicArray):
array._modify(force=True)
return array
def quick_sort(array: Array, **kwargs) -> Array:
"""
Performs quick sort on the given array.
Parameters
==========
array: Array
The array which is to be sorted.
start: int
The starting index of the portion
which is to be sorted.
Optional, by default 0
end: int
The ending index of the portion which
is to be sorted.
Optional, by default the index
of the last position filled.
comp: lambda/function
The comparator which is to be used
for sorting. If the function returns
False then only swapping is performed.
Optional, by default, less than or
equal to is used for comparing two
values.
pick_pivot_element: lambda/function
The function implementing the pivot picking
logic for quick sort. Should accept, `low`,
`high`, and `array` in this order, where `low`
represents the left end of the current partition,
`high` represents the right end, and `array` is
the original input array to `quick_sort` function.
Optional, by default, picks the element at `high`
index of the current partition as pivot.
Returns
=======
output: Array
The sorted array.
Examples
========
>>> from pydatastructs import OneDimensionalArray as ODA, quick_sort
>>> arr = ODA(int, [5, 78, 1, 0])
>>> out = quick_sort(arr)
>>> str(out)
'[0, 1, 5, 78]'
>>> arr = ODA(int, [21, 37, 5])
>>> out = quick_sort(arr)
>>> str(out)
'[5, 21, 37]'
References
==========
.. [1] https://en.wikipedia.org/wiki/Quicksort
"""
from pydatastructs import Stack
comp = kwargs.get("comp", lambda u, v: u <= v)
pick_pivot_element = kwargs.get("pick_pivot_element",
lambda low, high, array: array[high])
def partition(low, high, pick_pivot_element):
i = (low - 1)
x = pick_pivot_element(low, high, array)
for j in range(low, high):
if _comp(array[j], x, comp) is True:
i = i + 1
array[i], array[j] = array[j], array[i]
array[i + 1], array[high] = array[high], array[i + 1]
return (i + 1)
lower = kwargs.get('start', 0)
upper = kwargs.get('end', len(array) - 1)
stack = Stack()
stack.push(lower)
stack.push(upper)
while stack.is_empty is False:
high = stack.pop()
low = stack.pop()
p = partition(low, high, pick_pivot_element)
if p - 1 > low:
stack.push(low)
stack.push(p - 1)
if p + 1 < high:
stack.push(p + 1)
stack.push(high)
if _check_type(array, DynamicArray):
array._modify(force=True)
return array
def timsort(array : Array,start,end)-> Array:
"""
The Timsort algorithm is considered a hybrid sorting algorithm because
it employs a best-of-both-worlds combination of insertion sort and
merge sort. The main characteristic of Timsort is that it takes
advantage of already-sorted elements that exist in most real-world
datasets.These are called natural runs. The algorithm then iterates
over the list, collecting the elements into runs and merging them into
a single sorted list.
"""
"""
Parameters
========
array: Array
The required array to be sorted
start: int
The starting index of the portion
which is to be sorted.
Optional, by default 0
end: int
The ending index of the portion which
is to be sorted.
Optional, by default the index
of the last position filled.
Returns
=======
output: Array
The sorted list or array
Examples
========
>>> from pydatastructs import OneDimensionalArray, timsort
>>> arr = OneDimensionalArray(int,[-2, 7, 15, -14, 0, 15, 0] )
>>> timsort(arr, 0, 14)
>>> [arr[0], arr[1], arr[2], arr[3], arr[4], arr[5], arr[6]]
[ -14, -2, 0, 0, 7, 15, 15]
>>> from pydatastructs import OneDimensionalArray, timsort
>>> arr = OneDimensionalArray(int,[3, 2, 1])
>>> timsort(arr, 0, 2)
>>> [arr[0], arr[1], arr[2]]
[1, 2, 3]
References
==========
.. [1] https://en.wikipedia.org/wiki/Timsort
"""
min_run = 32
n = len(array)
# Start by slicing and sorting small portions of the
# input array. The size of these slices is defined by
# your `min_run` size.
for i in range(0, n, min_run):
insertion_sort(array, i, min((i + min_run - 1), n - 1))
# Now you can start merging the sorted slices.
# Start from `min_run`, doubling the size on
# each iteration until you surpass the length of
# the array.
size = min_run
while size < n:
# Determine the arrays that will
# be merged together
for start in range(0, n, size * 2):
# Compute the `midpoint` (where the first array ends
# and the second starts) and the `endpoint` (where
# the second array ends)
midpoint = start + size - 1
end = min((start + size * 2 - 1), (n-1))
# Merge the two subarrays.
# The `left` array should go from `start` to
# `midpoint + 1`, while the `right` array should
# go from `midpoint + 1` to `end + 1`.
merged_array = _merge(
left= array[start:midpoint + 1],
right= array[midpoint + 1:end + 1]
)
# Finally, put the merged array back into
# your array
array[start:start + len(merged_array)] = merged_array
# Each iteration should double the size of your arrays
size *= 2
if _check_type(array, DynamicArray):
array._modify(force=True)
