script to extract a subset of polygons for debugging

extract-range.py

@@ -0,0 +1,37 @@
+"""
+This works like the convert.py script but accepts a range of polygons to extract.
+This is useful for debugging the meshing code.
+
+Example usage:
+    $ python extract-range.py Norgeskyst.txt 2 4 > coast.txt
+
+This will extract polygons 2, 3, and 4 from the file Norgeskyst.txt and write
+them to coast.txt. First polygon is 1, not 0.
+"""
+
+import sys
+
+
+file_name = sys.argv[-3]
+start_polygon = int(sys.argv[-2])
+end_polygon = int(sys.argv[-1])
+
+current_polygon = 0
+with open(file_name, "r") as f:
+    _ = next(f)
+    _ = next(f)
+    while True:
+        try:
+            line = next(f)
+        except StopIteration:
+            break
+        n = int(line.split()[0])
+        current_polygon += 1
+        if current_polygon > end_polygon:
+            break
+        if start_polygon <= current_polygon <= end_polygon:
+            print(f"polygon {n}")
+        for _ in range(n):
+            line = next(f)
+            if start_polygon <= current_polygon <= end_polygon:
+                print(line.strip())