[OpenVino BackEnd]support np.count_nonzero for ov BackEnd (keras-team#20945)

* suppoer np.count_nonzero for ov BackEnd

* modifing function vars to lowercase

Author: Mohamed-Ashraf273

keras/src/backend/openvino/excluded_concrete_tests.txt

@@ -16,7 +16,6 @@ NumpyDtypeTest::test_bitwise
 NumpyDtypeTest::test_ceil
 NumpyDtypeTest::test_concatenate
 NumpyDtypeTest::test_correlate
-NumpyDtypeTest::test_count_nonzero
 NumpyDtypeTest::test_cross
 NumpyDtypeTest::test_cumprod
 NumpyDtypeTest::test_cumsum_bool
@@ -97,7 +96,6 @@ NumpyOneInputOpsCorrectnessTest::test_array
 NumpyOneInputOpsCorrectnessTest::test_bitwise_invert
 NumpyOneInputOpsCorrectnessTest::test_conj
 NumpyOneInputOpsCorrectnessTest::test_correlate
-NumpyOneInputOpsCorrectnessTest::test_count_nonzero
 NumpyOneInputOpsCorrectnessTest::test_cumprod
 NumpyOneInputOpsCorrectnessTest::test_diag
 NumpyOneInputOpsCorrectnessTest::test_diagonal

keras/src/backend/openvino/numpy.py

@@ -473,9 +473,21 @@ def cosh(x):
 
 
 def count_nonzero(x, axis=None):
-    raise NotImplementedError(
-        "`count_nonzero` is not supported with openvino backend"
-    )
+    x = get_ov_output(x)
+    zero_constant = ov_opset.constant(0, dtype=Type.i32).output(0)
+    zero_constant = ov_opset.convert_like(zero_constant, x)
+    x = ov_opset.not_equal(x, zero_constant).output(0)
+    x = ov_opset.convert(x, Type.i32).output(0)
+    if axis is None:
+        flatten_shape = ov_opset.constant([-1], Type.i32).output(0)
+        x = ov_opset.reshape(x, flatten_shape, False).output(0)
+        axis = 0
+    if isinstance(axis, tuple):
+        axis = list(axis)
+    if axis == []:
+        return OpenVINOKerasTensor(x)
+    axis = ov_opset.constant(axis, Type.i32).output(0)
+    return OpenVINOKerasTensor(ov_opset.reduce_sum(x, axis, False).output(0))
 
 
 def cross(x1, x2, axisa=-1, axisb=-1, axisc=-1, axis=None):