Error publishing data to topic

edit

Hello! I was working on a small python program to control a robot arm in Gazebo. My goal with this small program is to make the arm do an oscillating motion and I use /joint_group_pos_controller/command to publish the joint states.

This is the code:

#!/usr/bin/env python
# license removed for brevity
import rospy
from std_msgs.msg import String
from std_msgs.msg import Float64MultiArray
#from trajectory_msgs import JointTrajectory

def talker():
    pub = rospy.Publisher('/joint_group_pos_controller/command', Float64MultiArray, queue_size=10)
    rospy.init_node('arm_move_control', anonymous=True)
    rate = rospy.Rate(10) # 10hz

    while not rospy.is_shutdown():
        hello_str = "hello world %s" % rospy.get_time()
        rospy.loginfo(hello_str)
        data = [0.0, -2.0, 0.0, -1.57, 0.0, -0.5]
        pub.publish(1,data)
        rospy.sleep(4)
        data = [0.0, -1.57, 0.0, -2.0, 0.0, -1.5]
        pub.publish(1,data)
        rospy.sleep(4)

    if rospy.is_shutdown():
        rospy.loginfo("---- SHUTTING DOWN ----")

if __name__ == '__main__':
    try:
        talker()
    except rospy.ROSInterruptException:
        pass

So when I run the code I get this error:

[INFO] [1631362769.809577, 0.000000]: hello world 0.0
Traceback (most recent call last):
  File "/home/hdani-ros/catkin_ws/src/ur_keyboard_teleop/scripts/ur_keyboard_teleop.py", line 28, in <module>
    talker()
  File "/home/hdani-ros/catkin_ws/src/ur_keyboard_teleop/scripts/ur_keyboard_teleop.py", line 17, in talker
    pub.publish(data)
  File "/opt/ros/kinetic/lib/python2.7/dist-packages/rospy/topics.py", line 879, in publish
    data = args_kwds_to_message(self.data_class, args, kwds)
  File "/opt/ros/kinetic/lib/python2.7/dist-packages/rospy/msg.py", line 122, in args_kwds_to_message
    return data_class(*args)
  File "/opt/ros/kinetic/lib/python2.7/dist-packages/std_msgs/msg/_Float64MultiArray.py", line 74, in __init__
    super(Float64MultiArray, self).__init__(*args, **kwds)
  File "/opt/ros/kinetic/lib/python2.7/dist-packages/genpy/message.py", line 344, in __init__
    raise TypeError('Invalid number of arguments, args should be %s' % str(self.__slots__) + ' args are' + str(args))
TypeError: Invalid number of arguments, args should be ['layout', 'data'] args are([0.0, -2.0, 0.0, -1.57, 0.0, -0.5],)

Can someone clarify as to what I need to change in order to send just the joint states? Thanks in advance!