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Generic path to read a file in a ROS directory

asked 2017-10-26 14:58:36 -0500

robo_ninja gravatar image

updated 2017-10-27 10:11:32 -0500

I have created a /csv and /scripts directories in my /src directory. The /csv directory contains a csv file and /scripts directory contains a Python script to parse the csv file. The first few lines of the script is as follows -

import csv
with open('/home//default_ws/src/<package_name>/csv/alarms.csv', 'rb') as csvfile:
    reader = csv.reader(csvfile)
    for row in reader:

How can I add a generic location path for the csv file in my Python script? And what modifications do I need to make in my CMakelists.txt in order to install the /csv and /scripts directories?

* CORRECT ANSWER *

import csv
import os, rospkg
rospack = rospkg.RosPack()
with open(os.path.join(rospack.get_path("package_name"), "csv", "alarms.csv"), 'rb') as csvfile:
    reader = csv.reader(csvfile)
    for row in reader:
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answered 2017-10-27 03:42:54 -0500

l4ncelot gravatar image

updated 2017-10-27 03:44:55 -0500

To get path of your package you can use rospack package. Take a look at examples here.

This is basically it:

import rospkg 
rospack = rospkg.RosPack()
# get the file path for rospy_tutorials
rospack.get_path('rospy_tutorials')

In order to install your scripts you need to use cmake's install.

For example like this:

install(PROGRAMS
  "scripts/my_script"
  DESTINATION bin
)

Then it depends on if you're using catkin_make or catkin build command. To install the script you run catkin_make install. Or if you're using catkin build you need to config your package with catkin config config --install and then run catkin build.

This should install your script to install directory of your root's workspace.

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Comments

How should I modify with open('/home//default_ws/src/<package_name>/csv/alarms.csv', 'rb') as csvfile: in my code?

robo_ninja gravatar image robo_ninja  ( 2017-10-27 08:51:17 -0500 )edit

I'm not familiar with python. But I would probably save output of rospack.get_path('your_package') to some variable. Then somehow add the last part of your path (csv/alarms.csv) and insert it to open(). But this is already python related.

l4ncelot gravatar image l4ncelot  ( 2017-10-27 08:54:52 -0500 )edit

You should just be able to concatenate strings by adding them:

with open(rospack.get_path('<package_name>')+'/csv/alarms.csv', 'rb') as csvfile:
john.j.oneill gravatar image john.j.oneill  ( 2017-10-27 09:42:16 -0500 )edit
3

If I may suggest: always use os.path.join(..) instead of concatenating path segments with hard-coded path delimiters (ie: /). You never know where your code ends up.

gvdhoorn gravatar image gvdhoorn  ( 2017-10-27 09:48:10 -0500 )edit

It works! Thank you @gvdhoorn

robo_ninja gravatar image robo_ninja  ( 2017-10-27 10:26:11 -0500 )edit

If @l4ncelot's suggestion of using rospack for this worked, then I believe it would be good if you could mark his answer as the answer by ticking the checkmark to the left of it. It should turn green.

gvdhoorn gravatar image gvdhoorn  ( 2017-10-27 10:54:02 -0500 )edit

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Asked: 2017-10-26 14:58:36 -0500

Seen: 3,041 times

Last updated: Oct 27 '17