From 0747743e276953891635d7ae6b1590ea1ca3e667 Mon Sep 17 00:00:00 2001
From: Teschl <69400012+Teschl@users.noreply.github.com>
Date: Tue, 21 Jan 2025 16:35:08 +0100
Subject: [PATCH 1/3] Add aspect

---
 src/topotoolbox/grid_object.py | 47 +++++++++++++++++++++++++++++++---
 1 file changed, 43 insertions(+), 4 deletions(-)

diff --git a/src/topotoolbox/grid_object.py b/src/topotoolbox/grid_object.py
index 84743ca..898eefa 100755
--- a/src/topotoolbox/grid_object.py
+++ b/src/topotoolbox/grid_object.py
@@ -12,7 +12,8 @@
     generic_filter,
     grey_erosion,
     grey_dilation,
-    distance_transform_edt)
+    distance_transform_edt,
+    sobel)
 from scipy.signal import wiener
 from rasterio import CRS
 from rasterio.warp import reproject
@@ -74,7 +75,8 @@ def dims(self):
         if self.z.flags.f_contiguous:
             return (self.rows, self.columns)
 
-        raise TypeError("Grid is not stored as a contiguous row- or column-major array")
+        raise TypeError(
+            "Grid is not stored as a contiguous row- or column-major array")
 
     def reproject(self,
                   crs: 'CRS',
@@ -703,6 +705,44 @@ def evansslope(
         result.z = slope
         return result
 
+    def aspect(self, classify: bool = False) -> 'GridObject':
+        """Aspect returns the slope exposition of each cell in a digital
+        elevation model in degrees. In contrast to the second output of
+        gradient8 which returns the steepest slope direction, aspect 
+        returns the angle of the slope.
+
+        Parameters
+        ----------
+        classify : bool, optional
+            directions are classified according to the scheme proposed by
+            Gomez-Plaza et al. (2001), by default False
+
+        Returns
+        -------
+        GridObject
+            A GridObject containing the computed aspect data.
+        """
+
+        # [Nx,Ny] = surfnorm(Z);
+        # ASP   = cart2pol(Nx,Ny);
+        # ASP   = mod(90+ASP/pi*180,360);
+        grad_y, grad_x = np.gradient(self.z)
+        aspect = np.arctan2(-grad_x, grad_y)
+        aspect = np.degrees(aspect)
+        aspect = np.mod(aspect, 360)
+
+        if classify:
+            aspclass = np.array([1, 3, 5, 7, 8, 6, 4, 2])
+            aspedges = aspect // 45 + 1
+            aspedges = aspedges.astype(np.int8)
+
+            aspect[aspedges > 0] = aspclass[aspedges[aspedges > 0]-1]
+            aspect = aspect.astype(np.int8)
+
+        result = copy.copy(self)
+        result.z = aspect
+        return result
+
     def _gwdt_computecosts(self) -> np.ndarray:
         """
         Compute the cost array used in the gradient-weighted distance
@@ -837,12 +877,11 @@ def shufflelabel(self):
         result = copy.copy(self)
 
         labels = self.z
-        u,indices = np.unique(labels,return_inverse=True)
+        u, indices = np.unique(labels, return_inverse=True)
         result.z = np.random.permutation(u)[indices]
 
         return result
 
-
     # 'Magic' functions:
     # ------------------------------------------------------------------------
 

From c3d61c96b6b7fb620734f30746ddb1fb5b827c00 Mon Sep 17 00:00:00 2001
From: Teschl <69400012+Teschl@users.noreply.github.com>
Date: Tue, 21 Jan 2025 16:35:35 +0100
Subject: [PATCH 2/3] Remove Matlab references

---
 src/topotoolbox/grid_object.py | 3 ---
 1 file changed, 3 deletions(-)

diff --git a/src/topotoolbox/grid_object.py b/src/topotoolbox/grid_object.py
index 898eefa..e1b57ce 100755
--- a/src/topotoolbox/grid_object.py
+++ b/src/topotoolbox/grid_object.py
@@ -723,9 +723,6 @@ def aspect(self, classify: bool = False) -> 'GridObject':
             A GridObject containing the computed aspect data.
         """
 
-        # [Nx,Ny] = surfnorm(Z);
-        # ASP   = cart2pol(Nx,Ny);
-        # ASP   = mod(90+ASP/pi*180,360);
         grad_y, grad_x = np.gradient(self.z)
         aspect = np.arctan2(-grad_x, grad_y)
         aspect = np.degrees(aspect)

From 1e10c5a444807bb2e2b0f3e70afde63734e5aefc Mon Sep 17 00:00:00 2001
From: Teschl <69400012+Teschl@users.noreply.github.com>
Date: Wed, 22 Jan 2025 14:49:54 +0100
Subject: [PATCH 3/3] Modify edge_order

---
 src/topotoolbox/grid_object.py | 12 ++++++------
 1 file changed, 6 insertions(+), 6 deletions(-)

diff --git a/src/topotoolbox/grid_object.py b/src/topotoolbox/grid_object.py
index e1b57ce..f53bd9d 100755
--- a/src/topotoolbox/grid_object.py
+++ b/src/topotoolbox/grid_object.py
@@ -12,8 +12,8 @@
     generic_filter,
     grey_erosion,
     grey_dilation,
-    distance_transform_edt,
-    sobel)
+    distance_transform_edt
+)
 from scipy.signal import wiener
 from rasterio import CRS
 from rasterio.warp import reproject
@@ -723,17 +723,17 @@ def aspect(self, classify: bool = False) -> 'GridObject':
             A GridObject containing the computed aspect data.
         """
 
-        grad_y, grad_x = np.gradient(self.z)
-        aspect = np.arctan2(-grad_x, grad_y)
+        grad_y, grad_x = np.gradient(self.z, edge_order=2)
+        aspect: np.ndarray = np.arctan2(-grad_x, grad_y)
         aspect = np.degrees(aspect)
         aspect = np.mod(aspect, 360)
 
         if classify:
             aspclass = np.array([1, 3, 5, 7, 8, 6, 4, 2])
-            aspedges = aspect // 45 + 1
+            aspedges = aspect // 45
             aspedges = aspedges.astype(np.int8)
 
-            aspect[aspedges > 0] = aspclass[aspedges[aspedges > 0]-1]
+            aspect = aspclass[aspedges]
             aspect = aspect.astype(np.int8)
 
         result = copy.copy(self)