1 files changed, 62 insertions, 0 deletions
diff --git a/tools.py b/tools.py
new file mode 100644
index 0000000..51ef2e0
--- /dev/null
+++ b/tools.py
@@ -0,0 +1,62 @@
+import numpy as np
+
+def read_csv(filename):
+    """Return an array of comma-separated values from `filename`."""
+    f = open(filename)
+
+    points = []
+    for line in f:
+        try:
+            points.append([float(s) for s in line.split(',')])
+        except ValueError:
+            pass
+
+    f.close()
+
+    return np.array(points)
+
+def offset(points, x):
+    """
+    Return the set of points obtained by offsetting the edges of the profile
+    created by `points` by an amount `x`.
+
+    Args:
+        - points: array
+            Array of points which define the 2-D profile to be offset.
+        - x: float
+            Distance to offset the profile; a positive `x` value will offset
+            the profile in the direction of the profile path rotated 90 degrees
+            clockwise.
+    """
+    points = np.asarray(points)
+    points = np.array([points[0] - (points[1] - points[0])] + list(points) + [points[-1] - (points[-2] - points[-1])])
+    
+    offset_points = []
+    for i in range(1,len(points)-1):
+        v1 = np.cross(points[i]-points[i-1], (0,0,1))[:2]
+        v1 /= np.linalg.norm(v1)
+        v1 *= x
+
+        a = points[i-1] + v1
+        b = points[i] + v1
+
+        v2 = np.cross(points[i+1]-points[i], (0,0,1))[:2]
+        v2 /= np.linalg.norm(v2)
+        v2 *= x
+
+        c = points[i] + v2
+        d = points[i+1] + v2
+
+        m = np.empty((2,2))
+        m[:,0] = b-a
+        m[:,1] = c-d
+
+        try:
+            j = np.linalg.solve(m, c-a)[0]
+        except np.linalg.linalg.LinAlgError as e:
+            offset_points.append(b)
+            continue
+
+        offset_points.append((a + j*(b-a)))
+
+    return np.array(offset_points)