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First Search Program
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# ---------- | |
# User Instructions: | |
# | |
# Define a function, search() that returns a list | |
# in the form of [optimal path length, row, col]. For | |
# the grid shown below, your function should output | |
# [11, 4, 5]. | |
# | |
# If there is no valid path from the start point | |
# to the goal, your function should return the string | |
# 'fail' | |
# ---------- | |
# Grid format: | |
# 0 = Navigable space | |
# 1 = Occupied space | |
grid = [[0, 1, 0, 0, 0, 0], | |
[0, 1, 0, 1, 0, 0], | |
[0, 1, 0, 1, 0, 0], | |
[0, 1, 0, 1, 0, 0], | |
[0, 0, 0, 1, 0, 0]] | |
init = [0, 0] | |
goal = [len(grid)-1, len(grid[0])-1] | |
cost = 1 | |
delta = [[-1, 0], # go up | |
[ 0,-1], # go left | |
[ 1, 0], # go down | |
[ 0, 1]] # go right | |
delta_name = ['^', '<', 'v', '>'] | |
def remove_gval(gVal_and_coords): | |
return [gVal_and_coords[1], gVal_and_coords[2]] | |
def move(currentCell, movement): | |
return [currentCell[0] + movement[0], currentCell[1] + movement[1]] | |
def isOpenCell(x, y, grid=grid): | |
max_y = len(grid) | |
max_x = len(grid[0]) | |
#print(str(max_y) + " x " + str(max_x) + " grid") | |
isInsideGrid = (x >= 0 and x <=max_y - 1) and (y >= 0 and y <= max_x -1) | |
#print(str(x) + "," + str(y)) | |
#print("isInsideGrid: " + str(isInsideGrid)) | |
if(isInsideGrid == False): | |
#print("---") | |
return False | |
isBlocked = grid[x][y] == 1 | |
#print("isBlocked: " + str(isBlocked)) | |
#print("---") | |
return isBlocked == False | |
def getNeighbors(cell, delta=delta): | |
possibleNeighbors = [move(cell, m) for m in delta] | |
validNeighbors = [x for x in possibleNeighbors if isOpenCell(x[0], x[1])] | |
return validNeighbors | |
def search(grid,init,goal,cost, g_val = 0): | |
# ---------------------------------------- | |
# insert code here | |
# ---------------------------------------- | |
open = [[g_val, init[0], init[1]]] | |
#print("initial open list:") | |
#print(open) | |
#/prinprint("---") | |
expanded = [] | |
while True: | |
sortedItems = sorted(open, key=lambda open:open[0]) | |
if not sortedItems: | |
return "fail" | |
itemToExpand = sortedItems.pop(0) | |
itemToExpandCoord = remove_gval(itemToExpand) | |
#expanded.append(itemToExpandCoord) | |
if itemToExpandCoord == goal: | |
return itemToExpand | |
else: | |
#print("take list item") | |
#print(itemToExpand) | |
expanded.append(itemToExpandCoord) | |
neighbors = getNeighbors([itemToExpand[1], itemToExpand[2]]) | |
valid_neighbors = [n for n in neighbors if n not in expanded] | |
for vn in valid_neighbors: | |
expanded.append(vn) | |
g_val += 1 | |
for n in valid_neighbors: | |
sortedItems.append([itemToExpand[0]+1, n[0], n[1]]) | |
#print("new open list") | |
#print(sortedItems) | |
open = sortedItems | |
#return path | |
result = search(grid, init, goal, cost) | |
print(result) | |
#print(getNeighbors([0,0])) | |
''' | |
assert isOpenCell(-1,0,grid) == False, 'NOT Inside' | |
assert isOpenCell(0,-1,grid) == False, 'NOT Inside' | |
assert isOpenCell(0,0,grid) == True, 'Inside' | |
assert isOpenCell(0,5,grid) == True, 'Inside' | |
assert isOpenCell(6,0,grid) == False, 'NOT Inside' | |
assert isOpenCell(0,4,grid) == True, 'Inside' | |
assert isOpenCell(0,2,grid) == False, 'NOT Open (BLOCKED)' | |
assert isOpenCell(1,2,grid) == False, 'NOT Open (BLOCKED)' | |
assert isOpenCell(2,4,grid) == False, 'NOT Open (BLOCKED)' | |
assert isOpenCell(3,2,grid) == False, 'NOT Open (BLOCKED)' | |
assert isOpenCell(3,3,grid) == False, 'NOT Open (BLOCKED)' | |
assert isOpenCell(3,4,grid) == False, 'NOT Open (BLOCKED)' | |
assert isOpenCell(4,4,grid) == False, 'NOT Open (BLOCKED)' | |
assert isOpenCell(4,5,grid) == True, 'Open' | |
''' |
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