60 lines
1.7 KiB
Python
60 lines
1.7 KiB
Python
#!/usr/bin/python
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import numpy as np
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import matplotlib.pyplot as plt
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GRIDSIZE = 300
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INIT_CELLS = int(GRIDSIZE*0.2)
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MAX_TIME = 300
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EMPTY_CELL = -1
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DALLY_LIMIT = 0.2
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# query distance between two cars
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def get_distance(grid, i):
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dist = 0
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print(grid)
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while grid[(i+dist+1)%GRIDSIZE] == EMPTY_CELL and dist < 5:
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dist = dist + 1
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return dist
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# state transition t -> t + dt
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def update(grid_old, grid_new):
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for i in range(GRIDSIZE):
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if grid_old[i] != EMPTY_CELL:
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v = np.min((grid_old[i]+1, 5)) # accelerate
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dist = get_distance(grid_old, i)
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if i == 295:
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print(grid_old[i], " ", dist)
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quit()
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if v > dist: v = dist # break
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p = np.random.random()
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if p == DALLY_LIMIT: v = max(grid_old[i-1], 0)
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grid_new[(i+v)%GRIDSIZE] = v # move
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# allocate memory and initialise grids
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grid_old = np.full((GRIDSIZE), EMPTY_CELL, dtype=np.int32)
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grid_new = np.full((GRIDSIZE), EMPTY_CELL, dtype=np.int32)
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traffic = np.zeros((MAX_TIME, GRIDSIZE), dtype=np.int32)
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# set intial car positions and velocities
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for k in range(INIT_CELLS):
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while True:
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i = int(float(GRIDSIZE)*np.random.random())
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if grid_old[i] == EMPTY_CELL:
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grid_old[i] = int(float(6)*np.random.random())
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break
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# run updates
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for t in range(MAX_TIME):
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traffic[t,:] = grid_old[:]
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update(grid_old, grid_new)
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for i in range(GRIDSIZE):
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grid_old[i] = grid_new[i]
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grid_new[i] = EMPTY_CELL
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plt.xlabel('Cells')
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plt.ylabel('Timesteps')
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plt.imshow(traffic, cmap='Blues')
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plt.show()
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