SimPy yield hold 的语法错误

Question

我是 Simpy 的初学者。我只是按照手册的第一步 (http://simpy.sourceforge.net/old/SimPy_Manual/Manuals/Manual.html) 进行调整，使其适应我想做的事情。我的代码

# -*- coding: utf-8 -*-
#from mpl_toolkits.mplot3d import Axes3D
#from matplotlib import cm
#import matplotlib.pyplot as plt
import numpy as np
import random as rd
import math
from SimPy.Simulation import Process, activate, hold, initialize, simulate
import sys

class Agent(Process):
    def __init__(self,i,x,y,u,v,state):
        Process.__init__(self, name='Agent' + str(i))
        self.i = i
        self.x = x
        self.y = y
        self.u = u
        self.v = v
        self.st = state

    def go(self):
        dt=1.0/math.sqrt(self.u**2+self.v**2)
        print('%s starts at %s' %(self.i,now())
        yield hold, self, dt
        print('%s changed place at %s' %(self.i,now())

initialize()
a = Agent('nano',9,0,0,1,0)
#b = Agent(1,9,0,0,1,0)
activate(a,a.go(),at=0.0)
#activate(b,b.go(),at=5.0)
simulate(until=100.0)

引发以下错误：

hcecilia@helcecil:~/BRL$ python agent_sim.py 
  File "agent_sim.py", line 24
    yield hold, self, dt
        ^
SyntaxError: invalid syntax

但是当我尝试使用手册的确切代码时，它是：

from SimPy.Simulation import Process, activate, initialize, hold, now, simulate


class Message(Process):
    """A simple Process"""
    def __init__(self, i, len):
        Process.__init__(self, name='Message' + str(i))
        self.i = i
        self.len = len

    def go(self):
        print('%s %s %s' % (now(), self.i, 'Starting'))
        yield hold, self, 100.0
        print('%s %s %s' % (now(), self.i, 'Arrived'))


initialize()
p1 = Message(1, 203)   # new message
activate(p1, p1.go())  # activate it
p2 = Message(2, 33)
activate(p2, p2.go(), at=6.0)
simulate(until=200)
print('Current time is %s' % now())  # will print 106.0

它工作正常。我看不出两者有什么区别。如果您有任何想法...

Answer 1

您错过了前一行的结束 ) 括号：

print('%s starts at %s' %(self.i,now())
#    1                   2          332?

括号对编号1未闭合

在Python中，逻辑行只有在所有圆括号、方括号和大括号都闭合时才结束；没有右括号 yield 被视为 print() 函数调用的一部分，这不是有效语法。

SimPy yield hold 的语法错误

Syntax Error with SimPy yield hold

python

syntax

yield

generator

simpy