Use numpy.array's "offset" param instead of slicing

src/genpy/generate_numpy.py

@@ -56,11 +56,11 @@
     'byte' : 'numpy.int8',
     }
 # TODO: this doesn't explicitly specify little-endian byte order on the numpy data instance
-def unpack_numpy(var, count, dtype, buff):
+def unpack_numpy(var, offset, count, dtype, buff):
     """
     create numpy deserialization code
     """
-    return var + " = numpy.frombuffer(%s, dtype=%s, count=%s)"%(buff, dtype, count)
+    return var + " = numpy.frombuffer(%s, dtype=%s, count=%s, offset=%s)"%(buff, dtype, count, offset)
 
 def pack_numpy(var):
     """

src/genpy/generator.py

@@ -491,7 +491,7 @@ def array_serializer_generator(msg_context, package, type_, name, serialize, is_
                 yield "end += struct.calcsize(pattern)"
                 if is_numpy:
                     dtype = NUMPY_DTYPE[base_type]
-                    yield unpack_numpy(var, 'length', dtype, 'str[start:end]')
+                    yield unpack_numpy(var, 'start', 'length', dtype, 'str')
                 else:
                     yield unpack2(var, 'pattern', 'str[start:end]')
         else:
@@ -506,7 +506,7 @@ def array_serializer_generator(msg_context, package, type_, name, serialize, is_
                 yield "end += %s"%struct.calcsize('<%s'%pattern)
                 if is_numpy:
                     dtype = NUMPY_DTYPE[base_type]
-                    yield unpack_numpy(var, length, dtype, 'str[start:end]')
+                    yield unpack_numpy(var, 'start', length, dtype, 'str')
                 else:
                     yield unpack(var, pattern, 'str[start:end]')
         if not serialize and base_type == 'bool':

test/files/array/int16_fixed_deser_np.txt

@@ -1,3 +1,3 @@
 start = end
 end += 20
-data = numpy.frombuffer(str[start:end], dtype=numpy.int16, count=10)
+data = numpy.frombuffer(str, dtype=numpy.int16, count=10, offset=start)

test/files/array/int16_varlen_deser_np.txt

@@ -4,4 +4,4 @@ end += 4
 pattern = '<%sh'%length
 start = end
 end += struct.calcsize(pattern)
-data = numpy.frombuffer(str[start:end], dtype=numpy.int16, count=length)
+data = numpy.frombuffer(str, dtype=numpy.int16, count=length, offset=start)