问FuncAnimation仅返回一帧

EN

step_set = (-1, 0, 1)
    
def animate(t):
    global NpopCol,NpopA, NpopB, Npop,path, step,step_set,Bool, direction
    print(t)
    for i in range(0,Npop):
        path[i] =step[i]          
        direction =np.random.choice(step_set,2)
        for j in range(0,Npop):
            if(Bool[j]==1):
                if(path[j][0]==path[i][0])&(path[j][1]==path[i][1]):
                        Bool[i]=1 
        ##generate a path, moving 1 square right/left , up/down / diagonally
        step[i]=step[i]+ direction
    NpopCol=[]
    for i in range (0,Npop):
        if(Bool[i]==1):  
            NpopCol.append('r')
        if(Bool[i]==0)  &(i<NpopA)   : 
            NpopCol.append('b')
        if(Bool[i]==0)  &(i>=NpopA)   : 
            NpopCol.append('g')
    
    if (sum(Bool)==Npop) or t>250:
        anim.event_source.stop()
    ##t=t+1
    scat.set_offsets(path)   
    scat.set_color(NpopCol)     
    return scat,path
     

fig , ax=plt.subplots()
scat=plt.scatter(path[:,0], path[:,1],c=NpopCol,s=10)
anim=FuncAnimation(fig,animate,interval=10)
plt.show()