Adds a tool that filters leading slashes from topic names in bags. (#527)

PAIR=@cschuet

cartographer_ros/scripts/remove_leading_slashes.py

@@ -0,0 +1,53 @@
+#!/usr/bin/python
+# -*- coding: utf-8 -*-
+
+# Copyright 2016 The Cartographer Authors
+#
+# Licensed under the Apache License, Version 2.0 (the "License");
+# you may not use this file except in compliance with the License.
+# You may obtain a copy of the License at
+#
+#    http://www.apache.org/licenses/LICENSE-2.0
+#
+# Unless required by applicable law or agreed to in writing, software
+# distributed under the License is distributed on an "AS IS" BASIS,
+# WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+# See the License for the specific language governing permissions and
+# limitations under the License.
+"""A simple tool to remove leading slashes from frame names."""
+
+import argparse
+import os
+import rosbag
+
+
+def ParseArgs():
+  argument_parser = argparse.ArgumentParser(
+      description="Removes leading slashes from frame names.")
+  argument_parser.add_argument("input", type=str, help="Input bag")
+  return argument_parser.parse_args()
+
+
+def RewriteMsg(msg):
+  if hasattr(msg, "header"):
+    if msg.header.frame_id.startswith("/"):
+      msg.header.frame_id = msg.header.frame_id[1:]
+  if hasattr(msg, "child_frame_id"):
+    if msg.child_frame_id.startswith("/"):
+      msg.child_frame_id = msg.child_frame_id[1:]
+  if hasattr(msg, "transforms"):
+    for transform_msg in msg.transforms:
+      RewriteMsg(transform_msg)
+
+
+def Main():
+  options = ParseArgs()
+  with rosbag.Bag(os.path.splitext(options.input)[0] + ".filtered.bag",
+                  "w") as outbag:
+    for topic, msg, t in rosbag.Bag(options.input).read_messages():
+      RewriteMsg(msg)
+      outbag.write(topic, msg, msg.header.stamp if msg._has_header else t)
+
+
+if __name__ == "__main__":
+  Main()