8000 feat: add reverse edge pattern by goungoun · Pull Request #716 · graphframes/graphframes · GitHub
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feat: add reverse edge pattern #716

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feat: add reverse edge pattern #716

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52 changes: 29 additions & 23 deletions core/src/main/scala/org/graphframes/pattern/patterns.scala
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Original file line number Diff line number Diff line change
Expand Up @@ -31,42 +31,48 @@ private[graphframes] object PatternParser extends RegexParsers {
private val anonymousVertex: Parser[Vertex] = "" ^^ { _ => AnonymousVertex }
private val vertex: Parser[Vertex] = "(" ~> (vertexName | anonymousVertex) <~ ")"
private val namedEdge: Parser[Edge] =
vertex ~ "-" ~ "[" ~ "[a-zA-Z0-9_]+".r ~ "]" ~ "->" ~ vertex ^^ {
vertex ~ ("<-" | "-") ~ "[" ~ "[a-zA-Z0-9_]+".r ~ "]" ~ ("->" | "-") ~ vertex ^^ {
case src ~ "-" ~ "[" ~ name ~ "]" ~ "->" ~ dst => NamedEdge(name, src, dst)
case dst ~ "<-" ~ "[" ~ name ~ "]" ~ "-" ~ src => NamedEdge(name, src, dst)
case _ => throw new GraphFramesUnreachableException()
}
val anonymousEdge: Parser[Edge] =
vertex ~ "-" ~ "[" ~ "]" ~ "->" ~ vertex ^^ {
vertex ~ ("<-" | "-") ~ "[" ~ "]" ~ ("->" | "-") ~ vertex ^^ {
case src ~ "-" ~ "[" ~ "]" ~ "->" ~ dst => AnonymousEdge(src, dst)
case dst ~ "<-" ~ "[" ~ "]" ~ "-" ~ src => AnonymousEdge(src, dst)
case _ => throw new GraphFramesUnreachableException()
}
private val edge: Parser[Edge] = namedEdge | anonymousEdge
private val negatedEdge: Parser[Pattern] =
"!" ~ edge ^^ { case _ ~ e =>
Negation(e)
}
private val fixedLengthPattern: Parser[List[Edge]] =
vertex ~ "-" ~ "[" ~ "[a-zA-Z0-9_]*".r ~ "*" ~ "[0-9]+".r ~ "]" ~ "->" ~ vertex ^^ {
case src ~ "-" ~ "[" ~ name ~ "*" ~ num ~ "]" ~ "->" ~ dst => {
val hop: Int = num.toInt
if (hop == 1) {
List(if (name.isEmpty) AnonymousEdge(src, dst) else NamedEdge(name, src, dst))
} else if (hop > 1) {
val midVertices = (1 until hop).map(i => NamedVertex(s"_v$i"))
val vertices = src +: midVertices :+ dst
vertices
.sliding(2)
.zipWithIndex
.map {
case (Seq(v1, v2), i) =>
if (name.isEmpty) AnonymousEdge(v1, v2) else NamedEdge(s"_$name${i + 1}", v1, v2)
case _ => throw new GraphFramesUnreachableException()
}
.toList
} else {
throw new GraphFramesUnreachableException()

def generateFixedLengthPattern(src: Vertex, name: String, hop: Int, dst: Vertex): List[Edge] = {
if (hop == 1) {
List(if (name.isEmpty) AnonymousEdge(src, dst) else NamedEdge(name, src, dst))
} else if (hop > 1) {
val midVertices = (1 until hop).map(i => NamedVertex(s"_v$i"))
val vertices = src +: midVertices :+ dst
vertices
.sliding(2)
.zipWithIndex
.map {
case (Seq(v1, v2), i) =>
if (name.isEmpty) AnonymousEdge(v1, v2) else NamedEdge(s"_$name${i + 1}", v1, v2)
case _ => throw new GraphFramesUnreachableException()
}
}
.toList
} else {
throw new GraphFramesUnreachableException()
}
}
private val fixedLengthPattern: Parser[List[Edge]] =
vertex ~ ("<-" | "-") ~ "[" ~ "[a-zA-Z0-9_]*".r ~ "*" ~ "[0-9]+".r ~ "]" ~ ("->" | "-") ~ vertex ^^ {
case src ~ "-" ~ "[" ~ name ~ "*" ~ num ~ "]" ~ "->" ~ dst =>
generateFixedLengthPattern(src, name, num.toInt, dst)
case dst ~ "<-" ~ "[" ~ name ~ "*" ~ num ~ "]" ~ "-" ~ src =>
generateFixedLengthPattern(src, name, num.toInt, dst)
case _ => throw new GraphFramesUnreachableException()
}
private val pattern: Parser[Pattern] = edge | vertex | negatedEdge
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10 changes: 10 additions & 0 deletions core/src/test/scala/org/graphframes/pattern/PatternSuite.scala
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Expand Up @@ -84,6 +84,16 @@ class PatternSuite extends SparkFunSuite {
AnonymousEdge(NamedVertex("_v9"), NamedVertex("v"))))
}

test("good parses - reverse edge pattern") {
assert(Pattern.parse("(u)-[e]->(v)") === Pattern.parse("(v)<-[e]-(u)"))
assert(Pattern.parse("(u)-[]->(v)") === Pattern.parse("(v)<-[]-(u)"))
assert(Pattern.parse("(u)-[*5]->(v)") === Pattern.parse("(v)<-[*5]-(u)"))
assert(Pattern.parse("()-[e]->()") === Pattern.parse("()<-[e]-()"))
assert(
Pattern.parse("(u)-[]->(v); (v)-[]->(w); !(u)-[]->(w)") === Pattern.parse(
"(u)-[]->(v); (w)<-[]-(v); !(w)<-[]-(u)"))
}

test("bad parses") {
withClue("Failed to catch parse error with lone anonymous vertex") {
intercept[InvalidParseException] {
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0