[DOC] adds missing import statements in numba distance docstrings (#4376

)

Adds to #4264, also references #4324

Distance calculation docstrings currently do not import the actual method from sktime, which makes it inconvenient to use the examples for quick use.  This PR adds the import statement for each distance calculation in the docstring.

sktime/distances/_distance.py

@@ -91,6 +91,8 @@ def erp_distance(
 
     Examples
     --------
+    >>> import numpy as np
+    >>> from sktime.distances import erp_distance
     >>> x_1d = np.array([1, 2, 3, 4])  # 1d array
     >>> y_1d = np.array([5, 6, 7, 8])  # 1d array
     >>> erp_distance(x_1d, y_1d)
@@ -183,6 +185,8 @@ def edr_distance(
 
     Examples
     --------
+    >>> import numpy as np
+    >>> from sktime.distances import edr_distance
     >>> x_1d = np.array([1, 2, 3, 4])  # 1d array
     >>> y_1d = np.array([5, 6, 7, 8])  # 1d array
     >>> edr_distance(x_1d, y_1d)
@@ -370,6 +374,8 @@ def wddtw_distance(
 
     Examples
     --------
+    >>> import numpy as np
+    >>> from sktime.distances import wddtw_distance
     >>> x_1d = np.array([1, 2, 3, 4])  # 1d array
     >>> y_1d = np.array([5, 6, 7, 8])  # 1d array
     >>> wddtw_distance(x_1d, y_1d) # doctest: +SKIP
@@ -473,6 +479,8 @@ def wdtw_distance(
 
     Examples
     --------
+    >>> import numpy as np
+    >>> from sktime.distances import wdtw_distance
     >>> x_1d = np.array([1, 2, 3, 4])  # 1d array
     >>> y_1d = np.array([5, 6, 7, 8])  # 1d array
     >>> wdtw_distance(x_1d, y_1d)
@@ -572,6 +580,7 @@ def ddtw_distance(
     Examples
     --------
     >>> import numpy as np
+    >>> from sktime.distances import ddtw_distance
     >>> x_1d = np.array([1, 2, 3, 4])  # 1d array
     >>> y_1d = np.array([5, 6, 7, 8])  # 1d array
     >>> ddtw_distance(x_1d, y_1d) # doctest: +SKIP
@@ -893,6 +902,7 @@ def twe_distance(
     Examples
     --------
     >>> import numpy as np
+    >>> from sktime.distances import twe_distance
     >>> x_1d = np.array([1, 2, 3, 4])  # 1d array
     >>> y_1d = np.array([5, 6, 7, 8])  # 1d array
     >>> twe_distance(x_1d, y_1d)
@@ -959,6 +969,7 @@ def squared_distance(x: np.ndarray, y: np.ndarray, **kwargs: Any) -> float:
     Examples
     --------
     >>> import numpy as np
+    >>> from sktime.distances import squared_distance
     >>> x_1d = np.array([1, 2, 3, 4])  # 1d array
     >>> y_1d = np.array([5, 6, 7, 8])  # 1d array
     >>> squared_distance(x_1d, y_1d)
@@ -1012,6 +1023,7 @@ def euclidean_distance(x: np.ndarray, y: np.ndarray, **kwargs: Any) -> float:
     Examples
     --------
     >>> import numpy as np
+    >>> from sktime.distances import euclidean_distance
     >>> x_1d = np.array([1, 2, 3, 4])  # 1d array
     >>> y_1d = np.array([5, 6, 7, 8])  # 1d array
     >>> euclidean_distance(x_1d, y_1d)
@@ -1922,6 +1934,7 @@ def distance(
     Examples
     --------
     >>> import numpy as np
+    >>> from sktime.distances import distance
     >>> x_1d = np.array([1, 2, 3, 4])  # 1d array
     >>> y_1d = np.array([5, 6, 7, 8])  # 1d array
     >>> distance(x_1d, y_1d, metric='dtw')
@@ -2095,6 +2108,7 @@ def pairwise_distance(
     Examples
     --------
     >>> import numpy as np
+    >>> from sktime.distances import pairwise_distance
     >>> x_1d = np.array([1, 2, 3, 4])  # 1d array
     >>> y_1d = np.array([5, 6, 7, 8])  # 1d array
     >>> pairwise_distance(x_1d, y_1d, metric='dtw')