edge case in weights

pkg/src/dl.c

@@ -111,10 +111,10 @@ double dl_dist(
     ){
 
   if (!x){
-    return (double) y;
+    return (double) y * weight[1]; // ins weight
   }
   if (!y){
-    return (double) x;
+    return (double) x * weight[0]; // del weight
   }
 
   unsigned int swapCount, targetCharCount,i,j;

pkg/src/lv.c

@@ -28,23 +28,23 @@
  * - Extended with custom weights and maxDistance
  */
 double lv_dist(
-  unsigned int *a, int na, 
-  unsigned int *b, int nb, 
+  unsigned int *a, int na, // target
+  unsigned int *b, int nb, // source
   double *weight, 
   double *scores){
   if (!na){
-    return (double) nb;
+    return (double) nb * weight[1]; // del score
   }
   if (!nb){
-    return (double) na;
+    return (double) na * weight[0]; // ins score
   }
 
   int i, j;
   int I = na+1, L = na+1, J = nb+1;
   double sub;
 
   for ( i = 0; i < I; ++i ){
-    scores[i] = i * weight[0];
+    scores[i] = i * weight[1];
   }
   for ( j = 1; j < J; ++j, L += I ){
    scores[L] = j * weight[0];

pkg/src/osa.c

@@ -30,18 +30,18 @@
 double osa_dist(unsigned int *a, int na, unsigned int *b, int nb, double *weight, double *scores){
 
   if (!na){
-    return (double) nb;
+    return (double) nb * weight[1]; // ins weight
   }
   if (!nb){
-    return (double) na;
+    return (double) na * weight[0]; // del weight
   }
 
   int i, j;
   int M, I = na+1, L=na+1, J = nb+1;
   double sub, tran;
 
    for ( i = 0; i < I; ++i ){
-      scores[i] = i * weight[0];
+      scores[i] = i * weight[1];
    }
    for ( j = 1; j < J; ++j, L += I ){
       scores[L] = j * weight[0];

pkg/tests/testthat/testStringdist.R

@@ -55,6 +55,17 @@ test_that("weights are handled correctly",{
       stringdist("abc","ac",method='osa',weight=c(0.5,1,1,1)),
       stringdist("ac","abc",method='osa',weight=c(1,0.5,1,1))
    )
+
+  expect_equal( # two deletions from source (b) to target (a)
+    stringdist("","aa",weight=c(0.5,1,1,1),method="osa"),1
+  )
+  expect_equal( # two deletions from source (b) to target (a)
+    stringdist("","aa",weight=c(0.5,1,1,1),method="lv"),1
+  )
+  expect_equal( # two deletions from source (b) to target (a)
+    stringdist("","aa",weight=c(0.5,1,1,1),method="dl"),1
+  )
+
   # Thanks to Zach Price for reporting this bug.
   expect_equal(
     stringdist("ABC", "BC", method = "lv", weight = c(i=.1, d=.1, s=.1)),.1