Update readme

README.md

@@ -1,20 +1,28 @@
 # topic_tools
 
-This package is the ROS 2 port of http://wiki.ros.org/topic_tools
+This package is the ROS 2 port of https://wiki.ros.org/topic_tools
 
 Tools for directing, throttling, selecting, and otherwise manipulating ROS 2 topics at a meta-level. These tools do not generally perform serialization on the streams being manipulated, instead acting on generic binary data using `rclcpp`'s `GenericPublisher` and `GenericSubscription`.
 
 The tools in this package are provided as composable ROS 2 component nodes, so that they can be spawned into an existing process, launched from launchfiles, or invoked from the command line.
 
 ## Components
 
+- [Relay](#relay): Subscribes to a topic and republishes to another.
+- [RelayField](#relayfield): Republishes data in a different message type.
+- [Transform](#transform): Manipulates a topic or a field and outputs data on another topic.
+- [Throttle](#throttle): Republishes data with bandwidth or rate limit.
+- [Drop](#drop): Republishes by dropping X out of every Y incoming messages.
+- [Mux](#mux): Multiplexes incoming topics to an output.
+- [Delay](#delay): Delays and republishes incoming data.
+
 ### Relay
 
 Relay is ROS 2 node that subscribes to a topic and republishes all incoming data to another topic. It can work with any message type.
 
 #### Usage
 
-```
+```shell
 ros2 run topic_tools relay <intopic> [outtopic]
 ```
 
@@ -24,7 +32,7 @@ Subscribe to `intopic` and republish to either
 
 E.g. rename `base_scan` to `my_base_scan`:
 
-```
+```shell
 ros2 run topic_tools relay base_scan my_base_scan
 ```
 
@@ -39,29 +47,29 @@ ros2 run topic_tools relay base_scan my_base_scan
 
 ### RelayField
 
-RelayField is a ROS 2 node that allows to republish data in a different message type
+RelayField is a ROS 2 node that allows to republish data in a different message type.
 
 #### Usage
 
-```
+```shell
 ros2 run topic_tools relay_field <input topic> <output topic> <output type> [<expression on m>]
 ```
 
 Subscribe to `input topic` and republish one or many of its fields onto another field in a different message type
 
 E.g. publish the contents of the `data` field in a `std_msgs/msg/String` onto the `frame_id` field of a `std_msgs/msg/Header`:
 
-```
+```shell
 ros2 run topic_tools relay_field /chatter /header std_msgs/Header "{stamp: {sec: 0, nanosec: 0}, frame_id: m.data}"
 ```
 
 ### Transform
 
-Transform is a ROS 2 node that allows to take a topic or one of it fields and output it on another topic
+Transform is a ROS 2 node that allows to take a topic or one of it fields and output it on another topic.
 
 #### Usage
 
-```
+```shell
 ros2 run topic_tools transform <input topic> <output topic> <output type> [<expression on m>] [--import <modules>] [--field <topic_field>]
 ```
 
@@ -70,7 +78,7 @@ Subscribe to `input topic` and convert topic content or its field into
 
 E.g. transform `imu` orientation to `norm`:
 
-```
+```shell
 ros2 run topic_tools transform /imu --field orientation /norm std_msgs/Float64 'std_msgs.msg.Float64(data=numpy.sqrt(numpy.sum(numpy.array([m.x, m.y, m.z, m.w]))))' --import std_msgs numpy
 ```
 
@@ -82,35 +90,36 @@ Throttle is ROS 2 node that subscribes to a topic and republishes incoming data
 
 #### throttle message (rate)
 
-```
+```shell
 ros2 run topic_tools throttle messages <intopic> <msgs_per_sec> [outtopic]
 ```
 
 Throttle messages on `intopic` to a particular rate.
 - `intopic`: Incoming topic to subscribe to
-- `msgs_per_sec`: maximum messages per second to let through.
+- `msgs_per_sec`: Maximum messages per second to let through.
 - `outtopic`: Outgoing topic to publish on (default: intopic_throttle)
 
 E.g. throttle bandwidth-hogging laser scans (base_scan) to 1Hz:
 
-```
+```shell
 ros2 run topic_tools throttle messages base_scan 1.0
 ```
 
 #### throttle bytes (bandwidth)
 
-```
+```shell
 ros2 run topic_tools throttle bytes <intopic> <bytes_per_sec> <window> [outtopic]
 ```
 
 Throttle messages on `intopic` to a particular rate.
 - `intopic`: Incoming topic to subscribe to
-- `msgs_per_sec`: maximum messages per second to let through.
+- `bytes_per_sec`: Maximum bytes of messages per second to let through.
+- `window`: Time window in seconds to consider
 - `outtopic`: Outgoing topic to publish on (default: intopic_throttle)
 
 E.g. throttle bandwidth-hogging laser scans (base_scan) to 1KBps:
 
-```
+```shell
 ros2 run topic_tools throttle bytes base_scan 1024 1.0
 ```
 
@@ -124,6 +133,14 @@ ros2 run topic_tools throttle bytes base_scan 1024 1.0
     - If True, only subscribe to `input_topic` if there is at least one subscriber on the `output_topic`
 - `use_wall_clock` (bool, default=False)
     - If True, then perform all rate measurements against wall clock time, regardless of whether simulation / log time is in effect.
+- `throttle_type` (string, either `messages` or `bytes`)
+    - Method how to throttle
+- `msgs_per_sec` (double)
+    - Maximum messages per second to let through.
+- `bytes_per_sec` (integer)
+    - Maximum bytes of messages per second to let through.
+- `window` (double)
+    - Time window in seconds to consider
 
 ### Drop
 
@@ -132,7 +149,7 @@ It's mainly useful for limiting bandwidth usage, e.g., over a wireless link. It
 
 #### Usage
 
-```
+```shell
 ros2 run topic_tools drop <intopic> <X> <Y> [outtopic]
 ```
 
@@ -143,7 +160,7 @@ Subscribe to <intopic> and drop every <X> out of <Y> messages.
 
 E.g. drop every other message published to base_scan:
 
-```
+```shell
 ros2 run topic_tools drop base_scan 1 2
 ```
 
@@ -155,8 +172,8 @@ ros2 run topic_tools drop base_scan 1 2
     - the same as if provided as a command line argument
 - `lazy` (bool, default=False)
     - If True, only subscribe to `input_topic` if there is at least one subscriber on the `output_topic`
-- `X`, `Y` (int)
-    - drop X out of every Y incoming messages
+- `X` (int), `Y` (int)
+    - Drop X out of every Y incoming messages
 
 ### Mux
 
@@ -166,7 +183,7 @@ and to add and delete input topics. At startup, the first input topic on the com
 
 #### Usage
 
-```
+```shell
 ros2 run topic_tools mux <outopic> <intopic1> [intopic2...]
 ```
 
@@ -176,7 +193,7 @@ Subscribe to <intopic1>...N and publish currently selected topic to outopic. mux
 
 E.g. mux two command streams (auto_cmdvel and joystick_cmdvel) into one (sel_cmdvel):
 
-```
+```shell
 ros2 run topic_tools mux sel_cmdvel auto_cmdvel joystick_cmdvel
 ```
 
@@ -188,8 +205,8 @@ ros2 run topic_tools mux sel_cmdvel auto_cmdvel joystick_cmdvel
     - the same as if provided as a command line argument
 - `lazy` (bool, default=False)
     - If True, only subscribe to `input_topic` if there is at least one subscriber on the `output_topic`
-- `initial_topic` (str)
-    - Input topic to select on startup. If __none, start with no input topic. If unset, default to first topic in arguments
+- `initial_topic` (str, default="")
+    - Input topic to select on startup. If `__none`, start with no input topic. If unset, default to first topic in arguments
 
 ### Delay
 
@@ -198,7 +215,7 @@ It's useful to simulate computational results with high latency.
 
 #### Usage
 
-```
+```shell
 ros2 run topic_tools delay <intopic> <delay> [outtopic]
 ```
 
@@ -209,7 +226,7 @@ Subscribe to <intopic> and republish on <outtopic> delayed by <delay>.
 
 E.g. delay messages published to base_scan by 500ms:
 
-```
+```shell
 ros2 run topic_tools delay base_scan 0.5
 ```
 
@@ -219,7 +236,7 @@ ros2 run topic_tools delay base_scan 0.5
     - the same as if provided as a command line argument
 - `output_topic` (string, default=`<input_topic>_delay`)
     - the same as if provided as a command line argument
-- `lazy` (bool, default=False)
-    - If True, only subscribe to `input_topic` if there is at least one subscriber on the `output_topic`
-- `delay` (double)
-    - delay in seconds
+- `delay` (double, default=0.0)
+    - delay in seconds
+- `use_wall_clock` (bool, default=False)
+    - If True, then perform all rate measurements against wall clock time, regardless of whether simulation / log time is in effect.