mirror of
https://github.com/TheAlgorithms/Python.git
synced 2024-11-27 15:01:08 +00:00
07e991d553
* ci(pre-commit): Add pep8-naming to `pre-commit` hooks (#7038) * refactor: Fix naming conventions (#7038) * Update arithmetic_analysis/lu_decomposition.py Co-authored-by: Christian Clauss <cclauss@me.com> * [pre-commit.ci] auto fixes from pre-commit.com hooks for more information, see https://pre-commit.ci * refactor(lu_decomposition): Replace `NDArray` with `ArrayLike` (#7038) * chore: Fix naming conventions in doctests (#7038) * fix: Temporarily disable project euler problem 104 (#7069) * chore: Fix naming conventions in doctests (#7038) Co-authored-by: Christian Clauss <cclauss@me.com> Co-authored-by: pre-commit-ci[bot] <66853113+pre-commit-ci[bot]@users.noreply.github.com>
145 lines
4.2 KiB
Python
145 lines
4.2 KiB
Python
"""
|
|
This is an implementation of odd-even transposition sort.
|
|
|
|
It works by performing a series of parallel swaps between odd and even pairs of
|
|
variables in the list.
|
|
|
|
This implementation represents each variable in the list with a process and
|
|
each process communicates with its neighboring processes in the list to perform
|
|
comparisons.
|
|
They are synchronized with locks and message passing but other forms of
|
|
synchronization could be used.
|
|
"""
|
|
from multiprocessing import Lock, Pipe, Process
|
|
|
|
# lock used to ensure that two processes do not access a pipe at the same time
|
|
process_lock = Lock()
|
|
|
|
"""
|
|
The function run by the processes that sorts the list
|
|
|
|
position = the position in the list the process represents, used to know which
|
|
neighbor we pass our value to
|
|
value = the initial value at list[position]
|
|
LSend, RSend = the pipes we use to send to our left and right neighbors
|
|
LRcv, RRcv = the pipes we use to receive from our left and right neighbors
|
|
resultPipe = the pipe used to send results back to main
|
|
"""
|
|
|
|
|
|
def oe_process(position, value, l_send, r_send, lr_cv, rr_cv, result_pipe):
|
|
global process_lock
|
|
|
|
# we perform n swaps since after n swaps we know we are sorted
|
|
# we *could* stop early if we are sorted already, but it takes as long to
|
|
# find out we are sorted as it does to sort the list with this algorithm
|
|
for i in range(0, 10):
|
|
|
|
if (i + position) % 2 == 0 and r_send is not None:
|
|
# send your value to your right neighbor
|
|
process_lock.acquire()
|
|
r_send[1].send(value)
|
|
process_lock.release()
|
|
|
|
# receive your right neighbor's value
|
|
process_lock.acquire()
|
|
temp = rr_cv[0].recv()
|
|
process_lock.release()
|
|
|
|
# take the lower value since you are on the left
|
|
value = min(value, temp)
|
|
elif (i + position) % 2 != 0 and l_send is not None:
|
|
# send your value to your left neighbor
|
|
process_lock.acquire()
|
|
l_send[1].send(value)
|
|
process_lock.release()
|
|
|
|
# receive your left neighbor's value
|
|
process_lock.acquire()
|
|
temp = lr_cv[0].recv()
|
|
process_lock.release()
|
|
|
|
# take the higher value since you are on the right
|
|
value = max(value, temp)
|
|
# after all swaps are performed, send the values back to main
|
|
result_pipe[1].send(value)
|
|
|
|
|
|
"""
|
|
the function which creates the processes that perform the parallel swaps
|
|
|
|
arr = the list to be sorted
|
|
"""
|
|
|
|
|
|
def odd_even_transposition(arr):
|
|
process_array_ = []
|
|
result_pipe = []
|
|
# initialize the list of pipes where the values will be retrieved
|
|
for _ in arr:
|
|
result_pipe.append(Pipe())
|
|
# creates the processes
|
|
# the first and last process only have one neighbor so they are made outside
|
|
# of the loop
|
|
temp_rs = Pipe()
|
|
temp_rr = Pipe()
|
|
process_array_.append(
|
|
Process(
|
|
target=oe_process,
|
|
args=(0, arr[0], None, temp_rs, None, temp_rr, result_pipe[0]),
|
|
)
|
|
)
|
|
temp_lr = temp_rs
|
|
temp_ls = temp_rr
|
|
|
|
for i in range(1, len(arr) - 1):
|
|
temp_rs = Pipe()
|
|
temp_rr = Pipe()
|
|
process_array_.append(
|
|
Process(
|
|
target=oe_process,
|
|
args=(i, arr[i], temp_ls, temp_rs, temp_lr, temp_rr, result_pipe[i]),
|
|
)
|
|
)
|
|
temp_lr = temp_rs
|
|
temp_ls = temp_rr
|
|
|
|
process_array_.append(
|
|
Process(
|
|
target=oe_process,
|
|
args=(
|
|
len(arr) - 1,
|
|
arr[len(arr) - 1],
|
|
temp_ls,
|
|
None,
|
|
temp_lr,
|
|
None,
|
|
result_pipe[len(arr) - 1],
|
|
),
|
|
)
|
|
)
|
|
|
|
# start the processes
|
|
for p in process_array_:
|
|
p.start()
|
|
|
|
# wait for the processes to end and write their values to the list
|
|
for p in range(0, len(result_pipe)):
|
|
arr[p] = result_pipe[p][0].recv()
|
|
process_array_[p].join()
|
|
return arr
|
|
|
|
|
|
# creates a reverse sorted list and sorts it
|
|
def main():
|
|
arr = list(range(10, 0, -1))
|
|
print("Initial List")
|
|
print(*arr)
|
|
arr = odd_even_transposition(arr)
|
|
print("Sorted List\n")
|
|
print(*arr)
|
|
|
|
|
|
if __name__ == "__main__":
|
|
main()
|