Add service argument and start subscriber after client

image_recognition_color_extractor/scripts/get_colors_stream

@@ -7,12 +7,14 @@ from sensor_msgs.msg import Image
 
 from image_recognition_msgs.srv import Recognize
 
-class ExtractColorClient(object):
+class ExtractColorClient:
     def __init__(self, image_topic, color_service):
-        self.image_sub = rospy.Subscriber(image_topic, Image, self.color_callback)
         self.color_proxy = rospy.ServiceProxy(color_service, Recognize)
         self.color_proxy.wait_for_service(timeout=20)
 
+        # Subscriber will start immediately
+        self.image_sub = rospy.Subscriber(image_topic, Image, self.color_callback)
+
     def color_callback(self, msg):
         # Simply print out values in our custom message.
         colors = self.color_proxy(msg)
@@ -22,10 +24,11 @@ if __name__ == '__main__':
 
     parser = argparse.ArgumentParser(description='Get dominant colors from image')
     parser.add_argument('--topic', default='/image', type=str, help='Topic')
+    parser.add_argument('--service', default='extract_color', type=str, help='Service')
     args = parser.parse_args()
 
     rospy.init_node('color_extractor_stream')
 
-    extract_color_client = ExtractColorClient(args.topic, 'extract_color')
+    extract_color_client = ExtractColorClient(args.topic, args.service)
 
     rospy.spin()