在 Rospy 中更新全局变量 [英] Update the global variable in Rospy
问题描述
我有问题.我有两个节点，节点 1 和节点 2，其中节点 1 在节点 2 中发送浮点数，节点 2 在节点 1 中发送浮点数.在函数回调中，我想将收到的信息与其他值相加并更新变量.但问题是我没有成功发送信息，因为终端只在输出中打印第一次更新(对于节点 1，我得到 2.9，节点 2 得到 2.0)node1和node2的这些代码
i have the problem. I have two node, node 1 and node2, where node1 send a float number in node2 and node2 send a float number in node1. In the function callback, I want sum the information received with other value and update the variable. But the problem is that i don't succeed the information sent, because the terminal prints in output only first update(for node 1 i get 2.9, and node 2 2.0) These code for node1 and node2
<代码>
Node1
!/usr/bin/env python
import rospy
import time
from std_msgs.msg import Float64
global x1
global a
x1 = 1.5
def callback(msg):
#print 'Sto ricevendo informazioni da %s nel tempo %s' % (msg.data, time.ctime())
#print "%f"%msg.data
a = msg.data
info_nodo2 = a + 0.5
x1 = info_nodo2
print "%f"%x1
def nodo():
pub = rospy.Publisher('chatter1', Float64)
rospy.init_node('nodo1', anonymous=True)
rospy.loginfo("In attesa")
rospy.Subscriber('chatter2', Float64, callback)
rate = rospy.Rate(1) # 10hz
while not rospy.is_shutdown():
for i in range(1,51):
#rospy.loginfo(num)
pub.publish(x1)
rate.sleep()
rospy.spin()
if __name__ == '__main__':
try:
nodo()
except rospy.ROSInterruptException:
pass
<代码>
Node2
import rospy
import time
from std_msgs.msg import Float64
global x2
global a
x2 = 2.4
def callback(msg):
#print 'Sto ricevendo informazioni da %s nel tempo %s' % (msg.data, time.ctime())
#print "%f"%msg.data
a = msg.data
info_nodo1 = a + 0.5
x2 = info_nodo1
print "%f"%x2
def nodo():
pub = rospy.Publisher('chatter2', Float64)
rospy.init_node('nodo2', anonymous=True)
rospy.loginfo("In attesa")
rospy.Subscriber('chatter1', Float64, callback)
rate = rospy.Rate(1) # 10hz
while not rospy.is_shutdown():
for i in range(1,51):
# num = "%s" % (x2)
#rospy.loginfo(num)
pub.publish(x2)
rate.sleep()
rospy.spin()
if __name__ == '__main__':
try:
nodo()
except rospy.ROSInterruptException:
pass
推荐答案
问题是您将 x1 和 x2 声明为 global 变量.在每次迭代时，它们的值分别重置为 1.5 和 2.4.因此，发布的值是那些值加上 0.5(即 2.0 和 2.9).
The problem is you are declaring x1 and x2 as global variables. At every iteration their values get reset to 1.5 and 2.4, respectively. Thus, the published values are those values plus the 0.5 (i.e 2.0 and 2.9).
如果我理解正确，您希望两个节点不断更新彼此的值(对于 x1 和 x2).我把你的节点写成类，并用实例变量替换了全局变量:
If I understand correctly, you want the two nodes to continuously update each others values (for x1 and x2). I wrote your nodes as classes instead and replaced the global variables by instance variables:
节点 1:
#!/usr/bin/env python
# -*- encoding: utf-8 -*-
import rospy
import std_msgs.msg
class Nodo(object):
def __init__(self):
# Params
self.x1 = 1.5
self.a = None
# Node cycle rate (in Hz).
self.loop_rate = rospy.Rate(10)
# Publishers
self.pub = rospy.Publisher("~chatter1", std_msgs.msg.Float64, queue_size=10)
# Subscribers
rospy.Subscriber("~chatter2", std_msgs.msg.Float64, self.callback)
def callback(self, msg):
self.a = msg.data
self.x1 = self.a + 0.5
rospy.loginfo("x1: {}".format(self.x1))
def start(self):
rospy.loginfo("In attesa")
while not rospy.is_shutdown():
for ii in xrange(1, 51):
self.pub.publish(self.x1)
self.loop_rate.sleep()
if __name__ == '__main__':
rospy.init_node("nodo1", anonymous=True)
my_node = Nodo()
my_node.start()
节点 2:
#!/usr/bin/env python
# -*- encoding: utf-8 -*-
import rospy
import std_msgs.msg
class Nodo(object):
def __init__(self):
# Params
self.x2 = 2.4
self.a = None
# Node cycle rate (in Hz).
self.loop_rate = rospy.Rate(10)
# Publishers
self.pub = rospy.Publisher("~chatter2", std_msgs.msg.Float64, queue_size=10)
# Subscribers
rospy.Subscriber("~chatter1", std_msgs.msg.Float64, self.callback)
def callback(self, msg):
self.a = msg.data
self.x2 = self.a + 0.5
rospy.loginfo("x2: {}".format(self.x2))
def start(self):
rospy.loginfo("In attesa")
while not rospy.is_shutdown():
for ii in xrange(1, 51):
self.pub.publish(self.x2)
self.loop_rate.sleep()
if __name__ == '__main__':
rospy.init_node("nodo2", anonymous=True)
my_node = Nodo()
my_node.start()
运行这两个节点时，控制台输出如下:
When running these two nodes the console output is as follows:
process[nodo_1-1]: started with pid [7688]
process[nodo_2-2]: started with pid [7689]
[INFO] [WallTime: 1478865725.627418] In attesa
[INFO] [WallTime: 1478865725.627904] In attesa
[INFO] [WallTime: 1478865725.725064] x2: 2.0
[INFO] [WallTime: 1478865725.725512] x1: 2.5
[INFO] [WallTime: 1478865725.825050] x2: 3.0
[INFO] [WallTime: 1478865725.825448] x1: 3.5
[INFO] [WallTime: 1478865725.925056] x2: 4.0
[INFO] [WallTime: 1478865725.925608] x1: 4.5
[INFO] [WallTime: 1478865726.025061] x2: 5.0
[INFO] [WallTime: 1478865726.025617] x1: 5.5
[INFO] [WallTime: 1478865726.125045] x2: 6.0
[INFO] [WallTime: 1478865726.125605] x1: 6.5
[INFO] [WallTime: 1478865726.225033] x2: 7.0
[INFO] [WallTime: 1478865726.225586] x1: 7.5
[INFO] [WallTime: 1478865726.325013] x2: 8.0
[INFO] [WallTime: 1478865726.325606] x1: 8.5
[INFO] [WallTime: 1478865726.425041] x2: 9.0
[INFO] [WallTime: 1478865726.425608] x1: 9.5
[INFO] [WallTime: 1478865726.525057] x2: 10.0
[INFO] [WallTime: 1478865726.525545] x1: 10.5
[INFO] [WallTime: 1478865726.625054] x2: 11.0
希望这会有所帮助.
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