[python] Add convenience methods

1 files changed, 14 insertions, 3 deletions

diff --git a/python/src/mteval.pxi b/python/src/mteval.pxi
index 67a29f6f..d90eb9a6 100644
--- a/python/src/mteval.pxi
+++ b/python/src/mteval.pxi
@@ -10,6 +10,15 @@ cdef char* as_str(sentence, error_msg='Cannot convert type %s to str'):
         raise TypeError(error_msg % type(sentence))
     return ret
 
+cdef SufficientStats as_stats(x, y):
+    if isinstance(x, SufficientStats):
+        return x
+    elif x == 0 and isinstance(y, SufficientStats):
+        stats = SufficientStats()
+        stats.stats = new mteval.SufficientStats()
+        stats.metric = (<SufficientStats> y).metric
+        return stats
+
 cdef class Candidate:
     cdef mteval.Candidate* candidate
     cdef public float score
@@ -50,10 +59,12 @@ cdef class SufficientStats:
         self.stats[0] += other.stats[0]
         return self
 
-    def __add__(SufficientStats x, SufficientStats y):
+    def __add__(x, y):
+        cdef SufficientStats sx = as_stats(x, y)
+        cdef SufficientStats sy = as_stats(y, x)
         cdef SufficientStats result = SufficientStats()
-        result.stats = new mteval.SufficientStats(mteval.add(x.stats[0], y.stats[0]))
-        result.metric = x.metric
+        result.stats = new mteval.SufficientStats(mteval.add(sx.stats[0], sy.stats[0]))
+        result.metric = sx.metric
         return result
 
 cdef class CandidateSet: