Fix nanvar (#945)

Author: LukichevaPolina

dpnp/dpnp_algo/dpnp_algo_statistics.pyx

@@ -417,10 +417,10 @@ cpdef utils.dpnp_descriptor dpnp_min(utils.dpnp_descriptor input, axis):
 
 
 cpdef utils.dpnp_descriptor dpnp_nanvar(utils.dpnp_descriptor arr, ddof):
-    cdef utils.dpnp_descriptor mask_arr = dpnp_isnan(arr)
-    n = sum(mask_arr.get_pyobj())
+    # dpnp_isnan does not support USM array as input in comparison to dpnp.isnan
+    cdef utils.dpnp_descriptor mask_arr = dpnp.get_dpnp_descriptor(dpnp.isnan(arr.get_pyobj()))
+    n = dpnp.count_nonzero(mask_arr.get_pyobj())
     res_size = arr.size - n
-
     cdef DPNPFuncType param1_type = dpnp_dtype_to_DPNPFuncType(arr.dtype)
 
     cdef DPNPFuncData kernel_data = get_dpnp_function_ptr(DPNP_FN_NANVAR, param1_type, param1_type)

dpnp/dpnp_iface_counting.py

@@ -43,6 +43,9 @@
 import dpnp
 import numpy
 
+import dpnp.config as config
+from dpnp.dpnp_utils import *
+
 from dpnp.dpnp_algo.dpnp_algo import *  # TODO need to investigate why dpnp.dpnp_algo can not be used
 
 __all__ = [
@@ -72,7 +75,6 @@ def count_nonzero(x1, axis=None, *, keepdims=False):
     5
 
     """
-
     x1_desc = dpnp.get_dpnp_descriptor(x1)
     if x1_desc:
         if axis is not None:
@@ -85,4 +87,4 @@ def count_nonzero(x1, axis=None, *, keepdims=False):
 
             return result
 
-    return numpy.count_nonzero(x1, axis, keepdims=keepdims)
+    return call_origin(numpy.count_nonzero, x1, axis, keepdims=keepdims)