DBscan Adjacency Lists have repeated clusters

[MRIO]

Dear all,

I have been attempting to using dbscan on a 2D array (size: 2 x 1105 ) of point positions (results of UMAP), but i get this strange result, where there are repeated DbscanClusters inside the output array:

13-element Array{DbscanCluster,1}:
 DbscanCluster(17, [4, 12, 84, 90, 94, 675, 676, 737, 873, 965], [27, 108, 177, 880, 954, 1050, 1067])
 DbscanCluster(10, Int64[], [46, 48, 51, 57, 188, 225, 226, 228, 270, 542])
 DbscanCluster(11, [48, 51, 228], [46, 49, 57, 188, 225, 226, 270, 542])
 DbscanCluster(14, [418, 759, 832, 988, 1046], [830, 831, 855, 865, 989, 991, 996, 1021, 1070])
 DbscanCluster(10, Int64[], [624, 654, 664, 803, 805, 821, 859, 987, 1057, 1069])
 DbscanCluster(10, Int64[], [624, 654, 664, 803, 805, 821, 859, 987, 1057, 1069])
 DbscanCluster(10, Int64[], [624, 654, 664, 803, 805, 821, 859, 987, 1057, 1069])
 DbscanCluster(10, Int64[], [624, 654, 664, 803, 805, 821, 859, 987, 1057, 1069])
 DbscanCluster(10, Int64[], [624, 654, 664, 803, 805, 821, 859, 987, 1057, 1069])
 DbscanCluster(10, Int64[], [624, 654, 664, 803, 805, 821, 859, 987, 1057, 1069])
 DbscanCluster(10, Int64[], [624, 654, 664, 803, 805, 821, 859, 987, 1057, 1103])
 DbscanCluster(10, Int64[], [624, 654, 664, 803, 805, 821, 859, 987, 1057, 1103])
 DbscanCluster(11, [1057], [624, 654, 664, 803, 805, 821, 859, 987, 1069, 1103])

The data on which I'm applying dbscan looks sane (and there are no repeats):

Any idea why this is happening?

[alyst]

There was a bug in coordinate-based dbscan() implementation: it created a cluster even if there are no seeds/core points.
I suspect this duplication bug is related: the output shows some clusters that have no core (an empty 1st array), which is not correct.
This should be fixed by #248, so I will close it.
If this issue still remains, this issue could be reopened, but it would be nice to have a reproducible example.