Some changes for Rouge-S

Minor fix

minor fix

Author: Amartya Sanyal

measure.lua

@@ -57,6 +57,7 @@ function nn.get_rougeN(cand, ref, n, weight)
 end
 
 function nn.get_rougeS(cand, ref, beta, dskip)
+   local eps = 0.00000001
    local beta = beta or 1
    beta = beta * beta
 
@@ -77,18 +78,18 @@ function nn.get_rougeS(cand, ref, beta, dskip)
 
    for bigram, freq in pairs(ref_skip_bigrams) do
       local actual
-      if cand_skip_bigrams[bigram] == nil then
+      if cand_skip_bigrams[tostring(bigram)] == nil then
          actual = 0
       else
-         actual = cand_skip_bigrams[bigram]
+         actual = cand_skip_bigrams[tostring(bigram)]
       end
      correct = correct + math.min(actual, freq)
    end
    local total_skip_bigrams_ref = (dskip - 1)*(2 * #ref - dskip)/2
    local total_skip_bigrams_cand = (dskip - 1)*(2 * #cand - dskip)/2
    local rskip2 = correct/total_skip_bigrams_cand
    local pskip2 = correct/total_skip_bigrams_ref
-   local rouge = (1 + beta)*rskip2*pskip2/(rskip2 + beta*pskip2)
+   local rouge = (1 + beta)*rskip2*pskip2/(rskip2 + beta*pskip2 + eps)
    return rouge
 end
 

utils.lua

@@ -313,12 +313,11 @@ end
 
 function nn.utils.get_skip_bigrams(sent, ref, count, dskip)
    local skip_bigrams = {}
-   ref = ref or sent
    for beg = 1, #sent do
-      if ref[sent[beg]] then
+      if ref[tostring(sent[beg])] then
 	 local temp_token = sent[beg]
 	 for  last= beg+1, math.min(beg + dskip-1, #sent) do
-	    if ref[sent[last]] then
+	    if ref[tostring(sent[last])] then
 	       skip_bigram = temp_token..sent[last]
 	       if not count then
 		  skip_bigrams[skip_bigram] = 1