Add check that n_hashes is positive to the SignALSH constructor.

Author: kernelmethod

src/hashes/sign_alsh.jl

@@ -43,6 +43,8 @@ end
         quote
             if maxnorm < 0
                 "maxnorm must be non-negative" |> ErrorException |> throw
+            elseif n_hashes ≤ 0
+                "n_hashes must be positive" |> ErrorException |> throw
             elseif m ≤ 0
                 "m must be positive" |> ErrorException |> throw
             end
@@ -202,4 +204,5 @@ index_hash(h::SignALSH, x) = SignALSH_P(h, x)
 query_hash(h::SignALSH, x) = SignALSH_Q(h, x)
 
 n_hashes(h::SignALSH) = size(h.coeff_A, 1)
+similarity(::SignALSH) = inner_prod
 hashtype(::SignALSH) = BitArray{1}

test/hashes/test_sign_alsh.jl

@@ -21,6 +21,10 @@ Tests
         hashfn = SignALSH(; dtype=Float64, maxnorm=1)
         @test isa(hashfn, SignALSH{Float64})
 
+        # n_hashes must be positive
+        @test_throws ErrorException SignALSH(-1; maxnorm=1)
+        @test_throws ErrorException SignALSH( 0; maxnorm=1)
+
         # maxnorm must be specified and non-negative
         @test_throws ErrorException SignALSH()
         @test_throws ErrorException SignALSH(; maxnorm=-1)