def test_modify_key(backend):
heap = DHeap(backend)
populate_heap(heap, order='REVERSE')
for item in reversed([x for x in heap]):
heap.modifykey(item, -1)
assert heap.findminkey() == -1
assert heap.deletemin() == item
def spanning_tree_edges(graph, edge_weight):
components = UnionFind(memory_usage=graph.MemoryUsage)
sorted_edges = DHeap(memory_usage=graph.MemoryUsage)
for edge in graph.edges():
sorted_edges.insert(edge, key=edge_weight[edge])
while sorted_edges:
edge = sorted_edges.deletemin()
if components.link(*edge) is not None:
yield edge
def test_multiple_identical_keys(backend):
heap = DHeap(backend)
items = [x for x in xrange(100)] * 5
populate_heap(heap, items=items)
remove_items_from_heap(heap)
heap = DHeap(backend)
items = [x for x in 'abcdefghijklmnopqrstuvwxy']
key = dict(zip(items, [0,1,2,3,4] * 5))
populate_heap(heap, items=items, key=key)
preimages = dict()
for i in xrange(5):
preimages[i] = set(x for x,y in key.iteritems() if y == i)
for i in xrange(len(heap)):
item = heap.deletemin()
assert item in preimages[i / 5]
preimages[i / 5].remove(item)
