Use coords_array instead of scale_array variable

The scale is dervied from the 1D coordinates array
associated with a particlar axis. For clarity, this
commit replaces parameters/variables that use scale_array
with coords_array.

Author: elevans

src/imagej/dims.py

@@ -195,9 +195,9 @@ def _assign_axes(xarr: xr.DataArray):
         axis_str = _convert_dim(dim, direction="java")
         ax_type = jc.Axes.get(axis_str)
         ax_num = _get_axis_num(xarr, dim)
-        scale_arr = xarr.coords[dim].to_numpy()
+        coords_arr = xarr.coords[dim].to_numpy()
 
-        if _is_numeric_scale(scale_arr):
+        if _is_numeric_scale(coords_arr):
             doub_coords = [Double(np.double(x)) for x in xarr.coords[dim]]
         else:
             _logger.warning(
@@ -214,7 +214,7 @@ def _assign_axes(xarr: xr.DataArray):
         if EnumeratedAxis is not None:
             java_axis = EnumeratedAxis(ax_type, sj.to_java(doub_coords))
         else:
-            java_axis = _get_linear_axis(ax_type, scale_arr, sj.to_java(doub_coords))
+            java_axis = _get_linear_axis(ax_type, coords_arr, sj.to_java(doub_coords))
 
         axes[ax_num] = java_axis
 
@@ -284,23 +284,23 @@ def _get_enumerated_axis():
         return None
 
 
-def _get_linear_axis(axis_type: "jc.AxisType", scale_array: np.ndarray, values):
+def _get_linear_axis(axis_type: "jc.AxisType", coords_array: np.ndarray, values):
     """Get linear axis.
 
     This is used if no EnumeratedAxis is found. If EnumeratedAxis
     is available, use _get_enumerated_axis() instead.
     """
     DefaultLinearAxis = sj.jimport("net.imagej.axis.DefaultLinearAxis")
     origin = values[0]
-    if len(scale_array) <= 1:
+    if len(coords_array) <= 1:
         scale = 1
     else:
-        scale = _compute_slope(scale_array)
+        scale = _compute_slope(coords_array)
     axis = DefaultLinearAxis(axis_type, scale, origin)
     return axis
 
 
-def _compute_slope(axis):
+def _compute_slope(coords_array):
     """Compute slope (i.e. scale) of an axis.
 
     Each axis will have an associated coodinates array (1D) which
@@ -310,10 +310,10 @@ def _compute_slope(axis):
     array. The calculated slope is then used as the 'scale'
     parameter for creating an ImageJ2 DefaultLinenarAxis.
 
-    :param axis: List like 1D array with indexing.
+    :param coords_array: List like 1D array with indexing.
     :return: Slope of the axis.
     """
-    n = len(axis)
+    n = len(coords_array)
     sum_x = 0
     sum_y = 0
     sum_xy = 0
@@ -322,22 +322,22 @@ def _compute_slope(axis):
 
     for i in range(n):
         sum_x += i
-        sum_y += axis[i]
-        sum_xy += i * axis[i]
+        sum_y += coords_array[i]
+        sum_xy += i * coords_array[i]
         sum_x2 += i**2
-        sum_y2 += axis[i] ** 2
+        sum_y2 += coords_array[i] ** 2
 
     return ((n * sum_xy) - (sum_x * sum_y)) / ((n * sum_x2) - (sum_x**2))
 
 
-def _is_numeric_scale(scale: np.ndarray) -> bool:
+def _is_numeric_scale(coords_array: np.ndarray) -> bool:
     """
-    Checks if the scale of the given axis is numeric.
+    Checks if the coordinates array of the given axis is numeric.
 
-    :param scale: A 1D NumPy array.
+    :param coords_array: A 1D NumPy array.
     :return: bool
     """
-    return np.issubdtype(scale.dtype, np.number)
+    return np.issubdtype(coords_array.dtype, np.number)
 
 
 def _dataset_to_imgplus(rai: "jc.RandomAccessibleInterval") -> "jc.ImgPlus":