如何将所有对象添加到 Python 中的空列表？

Question

我创建了一个空列表，输出每个循环，只添加一个对象。将所有对象添加到列表后，重复如下所示的相同过程。

我不确定如何在一个循环中添加所有对象？

这是输出：

[u'person_0']
[u'person_0', u'chair_0']
[u'person_0', u'chair_0', u'chair_1']
[u'person_0', u'chair_0', u'chair_1', u'book_0']
[u'person_0', u'chair_0', u'chair_1', u'book_0', u'bottle_0']

我只需要最后一个输出：

[u'person_0', u'chair_0', u'chair_1', u'book_0', u'bottle_0']

这是完整代码：

#!/usr/bin/env python
# -*- coding: utf-8 -*-

import rospy
import numpy
import tf

from cv_bridge import CvBridge, CvBridgeError
from sensor_msgs import point_cloud2 as pc2
from sensor_msgs.msg import Image, PointCloud2
from dodo_detector.detection import SingleShotDetector
from dodo_detector_ros.msg import DetectedObject, DetectedObjectArray
import math

class Detector:

    def __init__(self):
        self._detector = SingleShotDetector('frozen_inference_graph.pb', 'mscoco_label_map.pbtxt', confidence=0.5)




        self._global_frame = rospy.get_param('~global_frame', None)
        self._tf_listener = tf.TransformListener()




        self._bridge = CvBridge()


        rospy.Subscriber("/camera/rgb/image_color", Image, self.image_callback)
        rospy.Subscriber('/camera/depth/points', PointCloud2, self.pc_callback)
        self._current_image = None
        self._current_pc = None


        self._imagepub = rospy.Publisher('~labeled_image', Image, queue_size=10)



        self._publishers = {None: (None, rospy.Publisher('~detected', DetectedObjectArray, queue_size=10))}




        self._tfpub = tf.TransformBroadcaster()
        rospy.loginfo('Ready to detect!')

    def image_callback(self, image):
        """Image callback"""

        self._current_image = image

    def pc_callback(self, pc):
        """Point cloud callback"""

        self._current_pc = pc

    def run(self):

        while not rospy.is_shutdown():

            if self._current_image is not None:
                try:


                    if self._global_frame is not None:
                        (trans, _) = self._tf_listener.lookupTransform('/' + self._global_frame, '/camera_link', rospy.Time(0))


                    scene = self._bridge.imgmsg_to_cv2(self._current_image, 'rgb8')
                    marked_image, objects = self._detector.from_image(scene)  # detect objects
                    self._imagepub.publish(self._bridge.cv2_to_imgmsg(marked_image, 'rgb8'))  # publish detection results


                    msgs = {}
                    for key in self._publishers:
                        msgs[key] = DetectedObjectArray()


                    my_tf_id = []
                    my_dis =[]
                    for obj_class in objects:

                        rospy.logdebug('Found ' + str(len(objects[obj_class])) + ' object(s) of type ' + obj_class)

                        for obj_type_index, coordinates in enumerate(objects[obj_class]):
#                     
                            rospy.logdebug('...' + obj_class + ' ' + str(obj_type_index) + ' at ' + str(coordinates))

                            ymin, xmin, ymax, xmax = coordinates
                            y_center = ymax - ((ymax - ymin) / 2)
                            x_center = xmax - ((xmax - xmin) / 2)

                            detected_object = DetectedObject()
                            detected_object.type.data = obj_class
                            detected_object.image_x.data = xmin
                            detected_object.image_y.data = ymin
                            detected_object.image_width.data = xmax - xmin
                            detected_object.image_height.data = ymax - ymin


                            publish_tf = False
                            if self._current_pc is None:
                                rospy.loginfo('No point cloud information available to track current object in scene')


                            else:

                                pc_list = list(pc2.read_points(self._current_pc, skip_nans=True, field_names=('x', 'y', 'z'), uvs=[(x_center, y_center)]))

                                if len(pc_list) > 0:

                                    publish_tf = True

                                    tf_id = obj_class + '_' + str(obj_type_index)        #object_number

                                    my_tf_id.append(tf_id)
                                    print my_tf_id




                                    detected_object.tf_id.data = tf_id



                                    point_x, point_y, point_z = pc_list[0] #point_z = x, point_x = y



                            if publish_tf:


                                object_tf = [point_z, -point_x, -point_y]

                                frame = 'cam_asus_link'

                                if self._global_frame is not None:
                                    object_tf = numpy.array(trans) + object_tf

                                    frame = self._global_frame

                                self._tfpub.sendTransform((object_tf), tf.transformations.quaternion_from_euler(0, 0, 0), rospy.Time.now(), tf_id, frame)

                except CvBridgeError as e:
                    print(e)
                except (tf.LookupException, tf.ConnectivityException, tf.ExtrapolationException) as e:
                    print(e)


if __name__ == '__main__':
    rospy.init_node('dodo_detector_ros', log_level=rospy.INFO)

    try:
        Detector().run()
    except KeyboardInterrupt:
        rospy.loginfo('Shutting down')

清空列表第 82 行 (my_tf_id = []) 并在第 119 行追加 (my_tf_id.append(tf_id))，最后在第 120 行使用 print my_tf_id

我正在使用 python 2.7、ROS、Opencv 来检测对象。

请帮助我或提出任何建议。

提前致谢

Answer 1

您正在 for 循环中打印列表。所以每次循环迭代时，它都会打印列表。尝试 print my_tf_id 在 for 循环之外

如何将所有对象添加到 Python 中的空列表？

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