Add python wrapper for ctc_evaluator

python/paddle/v2/fluid/layers/nn.py

@@ -50,6 +50,7 @@ __all__ = [
     'sequence_last_step',
     'dropout',
     'split',
+    'greedy_ctc_evaluator',
 ]
 
 
@@ -1597,3 +1598,39 @@ def split(input, num_or_sections, dim=-1):
             'axis': dim
         })
     return outs
+
+
+def greedy_ctc_evaluator(input, label, blank, normalized=False, name=None):
+    """
+    """
+
+    helper = LayerHelper("greedy_ctc_evalutor", **locals())
+    # top 1 op
+    topk_out = helper.create_tmp_variable(dtype=input.dtype)
+    topk_indices = helper.create_tmp_variable(dtype="int64")
+    helper.append_op(
+        type="top_k",
+        inputs={"X": [input]},
+        outputs={"Out": [topk_out],
+                 "Indices": [topk_indices]},
+        attrs={"k": 1})
+
+    # ctc align op
+    ctc_out = helper.create_tmp_variable(dtype="int64")
+    helper.append_op(
+        type="ctc_align",
+        inputs={"Input": [topk_indices]},
+        outputs={"Out": [ctc_out]},
+        attrs={"merge_repeated": True,
+               "blank": blank})
+
+    # edit distance op
+    edit_distance_out = helper.create_tmp_variable(dtype="int64")
+    helper.append_op(
+        type="edit_distance",
+        inputs={"Hyps": [ctc_out],
+                "Refs": [label]},
+        outputs={"Out": [edit_distance_out]},
+        attrs={"normalized": normalized})
+
+    return edit_distance_out