Closed IWANABETHATGUY closed 2 years ago
What i did wrong?
Variable::from_join
takes two inputs, the first is a Variable
that holds tuples of type (K, V1)
, and the second is a Relation
that holds tuples of type (K, V2)
. A join looks for all pairs of tuples in both inputs that share a "key" (a value of type K
) and calls the closure for each pair (whose values are of type V1
and V2
respectively).
In your case, the key is the source node for both edges and paths, so your join isn't doing what you want. For example, at the first iteration, it sees that the (0, 1)
in path_var
and the (0, 1)
in edges_var
have a shared key (0
), and your closure produces the combination of their values (1, 1)
. Repeating this process will give the same result as datafrog
does.
What you actually want is to make the shared key the source of one of the lists and the target of the other. You'll need to reverse one of the relations, probably edges
, to get this behavior.
Variable::from_join
takes two inputs, the first is aVariable
that holds tuples of type(K, V1)
, and the second is aRelation
that holds tuples of type(K, V2)
. A join looks for all pairs of tuples in both inputs that share a "key" (a value of typeK
) and calls the closure for each pair (whose values are of typeV1
andV2
respectively).In your case, the key is the source node for both edges and paths, so your join isn't doing what you want. For example, at the first iteration, it sees that the
(0, 1)
inpath_var
and the(0, 1)
inedges_var
have a shared key (0
), and your closure produces the combination of their values(1, 1)
. Repeating this process will give the same result asdatafrog
does.What you actually want is to make the shared key the source of one of the lists and the target of the other. You'll need to reverse one of the relations, probably
edges
, to get this behavior.
Thanks!
datalog code
exec
path(A, B)?
I getrust code
I get