roslaunch if condition

roslaunch

asked 2012-01-25 13:27:21 -0600

Yogi
411 ●12 ●15 ●21

updated 2021-09-26 18:52:08 -0600

lucasw

8729 ●137 ●239 ●256 https://github.com/lucasw

How can say: run this node if argX==y

The following does not work, and the documentation on this is lacking.

<node pkg="xxx" type="yyy" name="yyy" if="$(arg argX)==y" />

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34

answered 2017-10-09 12:01:24 -0600

adamconkey
642 ●8 ●17 ●18 https://adamconkey.github.io/

updated 2021-05-25 16:41:29 -0600

130s

10937 ●203 ●339 ●330 http://www.linkedin.co...

You can do this now in ROS Kinetic using eval:

<arg name="arg_name" default="desired_value"/>

<node pkg="node_pkg" type="node_type" name="node_name" 
      if="$(eval arg('arg_name') == 'desired_value')"/>

The documentation has been updated: http://wiki.ros.org/roslaunch/XML

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2

  <group if="$(eval arg('debug') ==0)">
    <node pkg="xxx" type="yyy" name="yyy">
  </group>

limitless ( 2017-12-02 14:52:22 -0600 )edit

worked for me. The above did not work for me.

Markus ( 2019-03-15 05:48:32 -0600 )edit

1

Updated the answer's description based on @limitless and @Markus' comments.

130s ( 2021-05-25 16:42:05 -0600 )edit

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8

answered 2012-01-25 14:37:19 -0600

kwc
12244 ●54 ●90 ●132 http://kwc.org/

The documentation on the roslaunch page for this syntax is complete, i.e. you can't do comparisons or any operators for that matter. You can only test the value itself.

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2

link to the documentation --- http://ros.org/wiki/roslaunch/XML

Kei Okada ( 2012-05-10 03:57:10 -0600 )edit

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4

answered 2017-10-04 02:03:44 -0600

toblech
86 ●1 ●3 ●3

This is supported as of ROS Kinetic.

<group if="$(arg foo)">
  <!-- stuff that will only be evaluated if foo is true -->
</group>

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This does not answer the question which is about comparing foo to some arbitrary (non-bool) value.

Felix Widmaier ( 2018-01-31 03:49:36 -0600 )edit

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2

answered 2015-06-25 11:57:15 -0600

thebyohazard
3542 ●52 ●68 ●83

updated 2015-06-30 14:16:59 -0600

Is this answer still current? I see that xacro got an upgrade: from http://wiki.ros.org/xacro#Conditional... "The more powerful evaluation capabilities in ROS Jade allow for much more complex expression. Virtually any python expression that evaluates to a Boolean is feasible."

EDIT 2015.6.30:

I found a related ticket suggesting that Ken's answer is probably still current, though I don't yet have jade to check for sure.

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0

answered 2021-11-25 17:57:22 -0600

ticotico
212 ●11 ●24 ●24

updated 2021-11-25 18:05:26 -0600

A small addendum from 2021. Embedding the if ...eval statement in a group gives a nice structure. As an example (taken from here):

<arg name="team" default="Red"/>
<arg name="type" default="painter"/>

<group if="$(eval team == 'Red')">
  <group if="$(eval type == 'painter')">
    <param name="robot_description" 
      command="$(find xacro)/xacro $(find robopaint)/urdf/red/paintbot_red.urdf.xacro" />
  </group>
  <group if="$(eval type == 'attacker')">
    <param name="robot_description" 
      command="$(find xacro)/xacro $(find robopaint)/urdf/red/attackbot_red.urdf.xacro" />
  </group>
</group>

<group if="$(eval team == 'Blue')">
  <group if="$(eval type == 'painter')">
    <param name="robot_description" 
      command="$(find xacro)/xacro $(find robopaint)/urdf/blue/paintbot_blue.urdf.xacro" />
  </group>
  <group if="$(eval type == 'attacker')">
    <param name="robot_description" 
      command="$(find xacro)/xacro $(find robopaint)/urdf/blue/attackbot_blue.urdf.xacro" />
  </group>
</group>