personenstromsimulation

personenstromsimulation/pedestrian_sk.py

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+#!/usr/bin/python
+
+import numpy as np
+import matplotlib.pyplot as plt
+
+GRIDSIZE_X = 35
+GRIDSIZE_Y = 35
+MAX_TIME = 500
+NUM_PEDS = 1
+
+CELL_PED = 1   # cell state: pedestrian
+CELL_EMP = 0   # cell state: empty
+CELL_OBS = -1  # cell state: obstacle
+
+EXIT_X = GRIDSIZE_X+1       # x-coordinate of exit
+EXIT_Y = int(GRIDSIZE_Y/2)  # y-coordinate of exit
+
+VIS_PAUSE = 0.2  # time [s] between two visual updates
+VIS_STEPS = 2    # stride [steps] between two visual updates
+
+# count pedestrians left in domain
+def count_peds(grid):
+    nped = 0
+    for x in range(1, GRIDSIZE_X+1):
+        for y in range(1, GRIDSIZE_Y+1):
+            if grid[x,y] == CELL_PED:
+                nped = nped + 1
+    return nped
+
+# compute average density [P/m2]
+def comp_density(grid):
+    dens = 0
+    for x in range(1, GRIDSIZE_X+1):
+        for y in range(1, GRIDSIZE_Y+1):
+            if grid[x,y] == CELL_PED:
+                npeds = 0
+                for i in range(-1,2):
+                    for j in range(-1,2):
+                        if grid[x+i,y+j] == CELL_PED:
+                            npeds = npeds + 1
+                dens = dens + (npeds/1.44)
+    if count_peds(grid) != 0:
+        return (dens/count_peds(grid))
+    else:
+        return 0
+
+# state transition t -> t + dt
+def update(old, new):
+    for x in range(1, GRIDSIZE_X+1):
+        for y in range(1, GRIDSIZE_Y+1):
+            #
+            # transition functions
+            #
+
+# allocate memory and initialise grids
+old = np.zeros((GRIDSIZE_X+2, GRIDSIZE_Y+2), dtype=np.int32)
+new = np.zeros((GRIDSIZE_X+2, GRIDSIZE_Y+2), dtype=np.int32)
+old[:,0] = CELL_OBS   # boundary: south
+old[:,-1] = CELL_OBS  # boundary: north
+old[0,:] = CELL_OBS   # boundary: west
+old[-1,:] = CELL_OBS  # boundary: east
+old[EXIT_X,EXIT_Y-1] = CELL_EMP  # exit
+old[EXIT_X,EXIT_Y] = CELL_EMP    # exit
+old[EXIT_X,EXIT_Y+1] = CELL_EMP  # exit
+new = old.copy()
+
+# set random starting points for pedestrians
+for i in range(NUM_PEDS):
+    while True:
+        x = int(float(GRIDSIZE_X)*np.random.random())+1
+        y = int(float(GRIDSIZE_Y)*np.random.random())+1
+        if old[x,y] == CELL_EMP:
+            old[x,y] = CELL_PED
+            break
+
+# run updates
+time = 0
+dens = []
+plt.ion()
+plt.imshow(np.rot90(old, 1))
+plt.pause(VIS_PAUSE)
+while count_peds(old) > 0 and time < MAX_TIME:
+    new[1:GRIDSIZE_X+1,1:GRIDSIZE_Y+1] = CELL_EMP
+    update(old, new)
+    new[EXIT_X,EXIT_Y-1] = CELL_EMP  # clear exit
+    new[EXIT_X,EXIT_Y] = CELL_EMP    # clear exit
+    new[EXIT_X,EXIT_Y+1] = CELL_EMP  # clear exit
+    old = new.copy()
+    numpeds = count_peds(old)
+    dens.append(comp_density(old))
+    time = time + 1
+    if time%VIS_STEPS == 0:
+      plt.clf()
+      plt.imshow(np.rot90(old, 1))
+      plt.pause(VIS_PAUSE)
+plt.ioff()
+print(f'Evacuation of {NUM_PEDS} persons done in {time*0.3:.2f} seconds')
+
+# plot density diagramm
+x = np.linspace(0,time*.3,time)
+plt.clf()
+plt.xlabel('Zeit [s]')
+plt.ylabel('Dichte [P/m2]')
+plt.plot(x, dens, 'r-')
+plt.show()