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Help with: Unable to import python module. "ModuleNotFoundError: No module named"

asked 2019-07-26 12:36:12 -0500

Equaltrace gravatar image

updated 2019-07-26 14:02:18 -0500

jayess gravatar image

Hi all

I know this question has been asked a lot of times, but it has been mostly relevant to when writing custom python modules and then importing them. My scenario is a bit different, I am trying to use the nmea_navsat_driver package. After cloning, it builds without any warnings/errors with catkin build. However, whenever I try to run the serial driver via. rosrun nmea_navsat_driver nmea_serial_driver _port:=/dev/ttyUSB0 _baud:=38400, I get the error

Traceback (most recent call last):
File "/home/fpbot/catkin_ws/src/nmea_navsat_driver/scripts/nmea_serial_driver", line 35, in <module> import libnmea_navsat_driver.nodes.nmea_serial_driver

ModuleNotFoundError: No module named 'libnmea_navsat_driver

This is a pretty standard package which is widely used. Regardless I have checked the requirements for importing python modules and everything seems to be aligned ros documentation. This leads me to assume that the err is on my end. But I am not able to figure it out. Kindly help.

P.S. I tried other packages which involve importing python modules. The issue was reproduced for each of those packages. Therefore, it is definitely not this particular package.

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answered 2019-07-26 14:06:15 -0500

jayess gravatar image

Are you sourceing your workspace? From the root of your workspace, run

source devel/setup.bash

Also, why clone and build it yourself? Are you not able to install this package using your package manager? It's available for Ubuntu using

sudo apt install ros-<ros-distro>-nmea-navsat-driver

Installing it using your package manager is the preferred method, if available of course.

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Hi jayess

Thanks for the reply. My sincerest apologies for the delayed response.

Yes, I am sourcing from the root of the workspace. It just gets called from the .bashrc file

I tried installing, but that didn't work either. The main reason, I try to clone and build myself is that it allows me to the make modifications to the package if I need to. (In this particular case, no modifications were made)

I tried running the same package on a different machines and it ran successfully. It is probably my ROS or Python setup. I have tried purging and reinstalling ROS but that didn't help. Not exactly sure how to troubleshoot this anymore.

Equaltrace gravatar image Equaltrace  ( 2019-07-29 21:44:15 -0500 )edit

I'd say that if you don't need to build this package then you should install it using your package manager and avoid this problem.

jayess gravatar image jayess  ( 2019-07-29 21:53:43 -0500 )edit

@jayess I did try after installation and got the same issue. I haven't been able to access the device again, but I will try to reinstall ROS and then try again.

Equaltrace gravatar image Equaltrace  ( 2019-08-02 14:37:47 -0500 )edit

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Asked: 2019-07-26 12:36:12 -0500

Seen: 7,476 times

Last updated: Jul 26 '19