add

src/compare.jl

@@ -135,9 +135,10 @@ function compare(s1::AbstractString, s2::AbstractString, dist::TokenSet)
     s0 = join(v0, " ")
     s1 = join(v1, " ")
     s2 = join(v2, " ")
+    isempty(s0) && return compare(s1, s2, dist.dist)
     max(compare(s0, s1, dist.dist), 
         compare(s0, s2, dist.dist),
-        compare(s1, s2, dist.dist)) 
+        compare(s1, s2, dist.dist))
 end
 
 

src/distances/edit.jl

@@ -193,8 +193,9 @@ end
 struct RatcliffObershelp <: PreMetric end
 
 function evaluate(dist::RatcliffObershelp, s1::AbstractString, s2::AbstractString)
-    n_matched = sum(last.(matching_blocks(s1, s2)))   
-    1.0 - 2 *  n_matched / (length(s1) + length(s2))
+    n_matched = sum(last.(matching_blocks(s1, s2)))  
+    len1, len2 = length(s1), length(s2)
+    len1 + len2 == 0 ? 0 : 1.0 - 2 *  n_matched / (len1 + len2)
 end
 
 function matching_blocks(s1::AbstractString, s2::AbstractString)

test/modifiers.jl

@@ -68,10 +68,13 @@ s = "HSINCHUANG"
 @test compare("mariners vs angels", "los angeles angels of anaheim at seattle mariners", TokenSet(RatcliffObershelp())) ≈ 1.0 - 0.09090909090909094
 
 
+@test compare("New York Mets vs Atlanta Braves", "", RatcliffObershelp())  ≈ 0.0
+
+
 @test compare("New York Mets vs Atlanta Braves", "", TokenSort(RatcliffObershelp()))  ≈ 0.0
 
 # ADD AGAIN
-#@test compare("mariners vs angels", "", TokenSet(RatcliffObershelp())) ≈ 0.0
+@test compare("mariners vs angels", "", TokenSet(RatcliffObershelp())) ≈ 0.0