boolean_node.py¶

What is this?¶

A node that takes bool values and returns the results of the boolean operation such as or, and, not and xor.

For example, this node can be used to merge the results of a node that outputs whether the robot is speaking in English or Japanese.

Subscribing Topics¶

Input is prepared for the ~number_of_input. A number suffix is added to the ~input. The suffixes start with 1. If ~number_of_input equals 2, subscribing topic names are ~input1 and ~input2. In the case of not operation, only ~input1 is subscribed.

~input{%d} (AnyMsg)

input value.

Publishing Topics¶

~output/or (std_msgs/Bool)

The result of the or operation.
~output/and (std_msgs/Bool)

The result of the and operation.
~output/not (std_msgs/Bool)

The result of the not operation.
~output/xor (std_msgs/Bool)

The result of the xor operation.

Parameters¶

~import (List[str], Default: [], Optional)

List of Python modules to import and use in ~input{%d}_condition expression. For commodity rospy and numpy modules are imported by default.

~input{%d}_condition (String, Default: m.data)

Returning bool value condition using the given Python expression. The Python expression can access any of the Python builtins plus: topic (the topic of the message), m (the message) and t (time of message).

For example, ~input1 topic is std_msgs/String and if you want to check whether a sentence is a hello, you can do the following.
```
input1_condition: m.data == 'hello'
```
If you want to check the frame id of the header, you can do the following.
```
input1_condition: m.header.frame_id in ['base', 'base_link']
```
The modules given to ~import can also be used.
```
condition_0: 'numpy.linalg.norm([m.wrench.force.x, m.wrench.force.y, m.wrench.force.z]) &lt; 10.0'
```
Note that this condition is evaluated each time a topic is published. For example, a condition that checks whether a certain topic has arrived within one second look like this.
```
input1_condition: "(rospy.Time.now() - t).to_sec() &lt; 1.0"
```
Use escape sequence when using the following symbols <(<), >(>), &(&), ‘(') and “(") in launch file.
~rate (Int, Default: 100)

Publishing rate [Hz].
~number_of_input (Int, Default: 2)

Number of input. ~number_of_input should be greater than 0.

Example¶

$ roslaunch jsk_topic_tools sample_boolean_node.launch

The outputs of a simple Boolean operation are as follows.

$ rostopic echo /robotsound/is_speaking -n1
data: True
---
$ rostopic echo /robotsound_jp/is_speaking -n1
data: False
---
$ rostopic echo /is_speaking -n1  # or
data: True
---
$ rostopic echo /both_are_speaking -n1  # and
data: False
---
$ rostopic echo /either_one_is_speaking -n1  # xor
data: True
---

In sample_boolean_node.launch, there is a description that gives input_condition as follows.

<node name="boolean_node_checking_conditions"
      pkg="jsk_topic_tools" type="boolean_node.py"
      clear_params="true" >
  <remap from="~input1" to="/image1" />
  <remap from="~input2" to="/image2" />
  <remap from="~input3" to="/chatter" />
  <rosparam>
    number_of_input: 3
    input1_condition: "'base' in m.header.frame_id"
    input2_condition: "'base' in m.header.frame_id"
    input3_condition: m.data == 'hello'
  </rosparam>
</node>

The output results when using the condition are as follows.

$ rostopic echo /image1 -n1
header:
  seq: 15029
  stamp:
    secs: 0
    nsecs:         0
  frame_id: "base"
height: 0
width: 0
encoding: ''
is_bigendian: 0
step: 0
data: []
---
$ rostopic echo /image2 -n1
header:
  seq: 32445
  stamp:
    secs: 0
    nsecs:         0
  frame_id: "base_link"
height: 0
width: 0
encoding: ''
is_bigendian: 0
step: 0
data: []
---
$ rostopic echo /chatter -n1
data: "hello"
---
$ rostopic echo /boolean_node_checking_conditions/output/and -n1
data: True
---
$ rostopic echo /boolean_node_checking_conditions/output/not -n1
data: False
---
$ rostopic echo /boolean_node_checking_conditions/output/or -n1
data: True
---
$ rostopic echo /boolean_node_checking_conditions/output/xor -n1
data: True
---