예제 #1
0
def sjt_local(pi, inv, x):
    # The goal of local(pi, inv, i) is to move i permutation pi with inverse
    # permutation inv in the direction of until it hits a "barrier", defined as
    # an element greater than it.
    d = -1
    while True:
        y = pi[inv[x] + d]  # y is the element next to x in direction d
        if x < y:
            d = -d  # Switch direction
            yield False
        else:
            transpose(pi, inv, x, y)
            yield True
예제 #2
0
def gen_all(n):
    # Pad on both sides to allow for a natural stop
    pi = [n + 1] + list(range(1, n + 1)) + [n + 1]
    inv = pi[:]
    # Keep track of directions, all starting negative (move left)
    d = [-1] * (n + 2)
    x = n  # x is the active element
    yield pi[1:-1]
    while x > 0:
        y = pi[inv[x] + d[x]]  # y is the element next to x in direction d[x]
        if x < y:
            d[x] = -d[x]  # Switch direction
            x -= 1  # Change active element to x - 1
        else:
            transpose(pi, inv, x, y)
            yield pi[1:-1]  # New permutation is generated
            x = n  # Change active element to n
예제 #3
0
def pruesse_ruskey_product(poset, pi, inv, X, a, b):
    Y_ab = pruesse_ruskey_local(poset, pi, inv, a, b)
    Y_ba = pruesse_ruskey_local(poset, pi, inv, b, a)
    while True:
        for result in Y_ab:
            if not result:
                break
            yield result

        for result in X:
            if not result:
                break
            if result is SWITCH_SIGN:
                transpose(pi, inv, a, b)
                Y_ab, Y_ba = Y_ba, Y_ab
            yield True
            for result in Y_ab:
                if not result:
                    break
                yield result
        yield False