feat(frontend): implement type_of_target utility function in sklearn …

…frontend utils along with example based test. This function has repeated use in implementations

ivy/functional/frontends/sklearn/utils/__init__.py

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+from . import multiclass
+from .multiclass import *

ivy/functional/frontends/sklearn/utils/multiclass.py

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+import ivy
+
+
+# reapeated utility function
+def type_of_target(y, input_name='y'):
+    # purely utility function
+    # TODO: implement multilabel-indicator, ...-multioutput, unknown
+    if y.ndim not in (1, 2):
+        return "unknown"
+    if ivy.is_float_dtype(y) and ivy.any(ivy.not_equal(y, y.astype('int64'))):
+        return "continuous"
+    else:
+        vals = ivy.unique_values(y)
+        if len(vals) > 2:
+            return "multiclass"
+        else:
+            return "binary"

ivy_tests/test_ivy/test_frontends/test_sklearn/test_utils/test_multiclass.py

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+import pytest
+import ivy
+from ivy.functional.frontends.sklearn.utils.multiclass import type_of_target
+
+
+# not suitable for usual frontend testing
+@pytest.mark.parametrize("y, label", [([1.2], "continuous"),
+                               ([1], "binary"),
+                               ([1, 2], "binary"),
+                               ([1, 2, 3], "multiclass"),
+                               ([1, 2, 3, 4], "multiclass"),
+                               ([1, 2, 3, 4, 5], "multiclass"),
+                               ([1, 2, 2], "binary"),
+                               ([1, 2., 2, 3], "multiclass"),
+                               ([1., 2., 2.], "binary")])
+def test_sklearn_type_of_target(y, label):
+    assert type_of_target(ivy.array(y)) == label