bugfix/feature: support values <1 for weighted graphs

Author: brean

CHANGELOG.md

@@ -1,3 +1,7 @@
+# 1.0.13
+## Features/Bugfix
+- allow for path finding with float values as cost.
+
 # 1.0.12
 ## Bugfixes
 - fix for passable borders (see #62, merges #63)

pathfinding/core/graph.py

@@ -49,7 +49,7 @@ def neighbors(self, node: GraphNode, **kwargs):
                 if edge[1] == node]
         return nodes
 
-    def calc_cost(self, node_a, node_b, weighted=False):
+    def calc_cost(self, node_a, node_b, _weighted=False):
         for edge in self.edges:
             if edge[0].node_id == node_a.node_id and \
                     edge[1].node_id == node_b.node_id:

pathfinding/core/grid.py

@@ -25,12 +25,12 @@ def build_nodes(
         for x in range(width):
             # 0, '0', False will be obstacles
             # all other values mark walkable cells.
-            # you can use values bigger then 1 to assign a weight.
+            # you can use values bigger then 0 to assign a weight.
             # If inverse is False it changes
             # (1 and up becomes obstacle and 0 or everything negative marks a
             #  free cells)
-            weight = int(matrix[y][x]) if use_matrix else 1
-            walkable = weight <= 0 if inverse else weight >= 1
+            weight = float(matrix[y][x]) if use_matrix else 1
+            walkable = weight <= 0.0 if inverse else weight > 0
 
             nodes[y].append(GridNode(
                 x=x, y=y, walkable=walkable, weight=weight, grid_id=grid_id))
@@ -121,9 +121,6 @@ def neighbors(
         neighbors = []
         north = nw = east = ne = south = se = west = sw = False
 
-        lr = self.passable_left_right_border
-        ud = self.passable_up_down_border
-
         # ↑
         if y == 0 and self.passable_up_down_border:
             north_y = self.height - 1
@@ -143,7 +140,7 @@ def neighbors(
         if self.walkable(east_x, y):
             neighbors.append(self.nodes[y][east_x])
             east = True
-        
+
         # ↓
         if y == self.height - 1 and self.passable_up_down_border:
             south_y = 0
@@ -207,7 +204,7 @@ def neighbors(
                 ne_y = y - 1
             if self.walkable(ne_x, ne_y):
                 neighbors.append(self.nodes[ne_y][ne_x])
-        
+
         # ↘
         if se:
             if x == self.width - 1 and self.passable_left_right_border:
@@ -273,9 +270,9 @@ def grid_str(self, path=None, start=None, end=None,
         data = ''
         if border:
             data = f'+{"-" * len(self.nodes[0])}+'
-        for y in range(len(self.nodes)):
+        for y, _ in enumerate(self.nodes):
             line = ''
-            for x in range(len(self.nodes[y])):
+            for x, _ in enumerate(self.nodes[y]):
                 node = self.nodes[y][x]
                 if node == start:
                     line += start_chr

pathfinding/core/node.py

@@ -77,7 +77,7 @@ class GridNode(Node):
     walkable: bool = True
 
     # used for weighted algorithms
-    weight: float = 1.0
+    weight: float = 0.0
 
     # grid_id is used if we have more than one grid,
     # normally we just count our grids by number

pathfinding/finder/finder.py

@@ -1,4 +1,3 @@
-import heapq  # used for the so colled "open list" that stores known nodes
 import time  # for time limitation
 from ..core.grid import Grid
 from ..core.diagonal_movement import DiagonalMovement
@@ -74,7 +73,14 @@ def apply_heuristic(self, node_a, node_b, heuristic=None, graph=None):
             if graph.passable_up_down_border and dy > graph.height / 2:
                 dy = graph.height - dy
 
-        return heuristic(dx, dy)
+            nh = heuristic(dx, dy)
+            # in a weighted graph we also need to multiply the calculated
+            # value with the weight of the node
+            if self.weighted:
+                nh *= node_a.weight
+            return nh
+        else:
+            return heuristic(dx, dy)
 
     def find_neighbors(self, grid, node, diagonal_movement=None):
         '''

setup.py

@@ -2,16 +2,16 @@
 from setuptools import find_packages, setup
 
 
-with open("README.md", "r") as fh:
+with open("README.md", "r", encoding='utf-8') as fh:
     long_description = fh.read()
 
 setup(
     name="pathfinding",
-    description="Pathfinding algorithms (based on Pathfinding.JS)",
+    description="Path finding algorithms (based on Pathfinding.JS)",
     long_description=long_description,
     long_description_content_type="text/markdown",
     url="https://github.com/brean/python-pathfinding",
-    version="1.0.12",
+    version="1.0.13",
     license="MIT",
     author="Andreas Bresser",
     packages=find_packages(),

test/path_test_scenarios.json

@@ -102,12 +102,13 @@
         "passableLeftRightBorder": true
     },
     {
+        "name": "s7",
         "startX": 0,
         "startY": 0,
         "endX": 4,
         "endY": 0,
         "matrix": [
-          [0.01, 0.02, 0.99, 0.09, 0.01],
+          [0.01, 0.02, 0.09, 0.19, 0.01],
           [0.01, 0.02,    0,    0, 0.01],
           [0.01, 0.01,    0, 0.01, 0.01],
           [0.08, 0.03,    0, 0.01, 0.01],

test/test_path.py

@@ -53,7 +53,7 @@ def test_path():
             if weighted and not finder.weighted:
                 continue
             path, _ = finder.find_path(start, end, grid)
-            print(find.__name__)
+            print(scenario['name'], find.__name__)
             print(grid.grid_str(path=path, start=start, end=end,
                                 show_weight=weighted))
             print('path: {}'.format(path))
@@ -75,7 +75,8 @@ def test_path_diagonal():
                 continue
 
             path, runs = finder.find_path(start, end, grid)
-            print(find.__name__, runs, len(path))
+            print(scenario['name'], find.__name__, runs, len(path))
+            print(grid.grid_str(start=start, end=end))
             print(grid.grid_str(path=path, start=start, end=end,
                                 show_weight=weighted))
             print('path: {}'.format(path))