undefined symbol: cs_di_schol

[thomasfermi]

Installation completed, but when I import g2o I get

ImportError: /mypath/python3.6/site-packages/g2o.cpython-36m-x86_64-linux-gnu.so: undefined symbol: cs_di_schol

Im using Linux Mint 18.3 (which is based on Ubuntu 16.04)

[cyc790]

I encountered the same problem,have you solved it? @thomasfermi

[thomasfermi]

Hi @cyc790
No, sorry. I gave up.

[ferreram]

Hi @thomasfermi and @cyc790,
I had the same issue and I solved it by installing libqglviewer-dev.

Hope it can work for you too.
Cheers!

[district10]

Hi @thomasfermi and @cyc790,
I had the same issue and I solved it by installing libqglviewer-dev.

Hope it can work for you too.
Cheers!

reinstalled my libqglviewer-dev and it works now, thanks a lot

[AmaurX]

Hi!
I tried to install everything with anaconda (and python3.7). The install works as well, but I get the same problem :
ImportError: /mypath/python3.7/site-packages/g2o.cpython-36m-x86_64-linux-gnu.so: undefined symbol: cs_di_schol

Notice that mypath here is actually "HOME/anaconda3/envs/py37/lib/".

I tried reinstalling libqglviewer-dev but it didn't change anything. It might be because the .so file is in our custom path in anaconda and not in /usr/lib

Then I reconstructed everything outside of anaconda (with python3.5) and it works.

Any idea on how to make things work in anaconda?

[lvgeng]

Hi @thomasfermi and @cyc790,
I had the same issue and I solved it by installing libqglviewer-dev.

Hope it can work for you too.
Cheers!

I am not so sure if it is a recent change.
Currently, there are two versions of libqglviewer-dev.

libqglviewer-dev-qt4 and libqglviewer-dev-qt5

The key is libqglviewer-dev-qt4 need to be installed. Well... kind of hard to understand but it it works...
And I assume that qt4 or qt5 only plays a part in visualization, I guess it would not affect the performance of graph optimization.

Hope so...

[kochaika]

Hi!
For me worked:

1. install libqglviewer-dev (or libqglviewer-dev-qt4 like @lvgeng noticed)
2. install libsuitesparse-dev
3. rebuild g2opy

Maybe it will be useful to someone.

[CydKnocking]

Hi!
I encountered the problem of Segmentation fault when I directly import g2o at the very beginning of python 3.5.2:
>>> import g2o
Segmentation fault (core dumped)
But when I import g2o after importing a module that doesn't exist, undefined symbol error occurs:
>>> import ggg
Traceback (most recent call last):
File "<stdin>", line 1, in <module>
ImportError: No module named 'ggg'
>>> import g2o
Traceback (most recent call last):
File "<stdin>", line 1, in <module>
ImportError: /usr/lib/python3/dist-packages/g2o.cpython-35m-x86_64-linux-gnu.so: undefined symbol: cs_di_schol
I've tried to install libqglviewer-dev (or libqglviewer-dev-qt4) and libsuitesparse-dev and rebuild g2opy mentioned by @pro100kot but nothing worked.
I don't know whether these two problems are the same. Either do I know how to fix them...

[marctuscher]

Hi,
installing http://libqglviewer.com/download.html from source worked for me.

[shaoxh]

Hi,
installing http://libqglviewer.com/download.html from source worked for me.
Hi,
tried this, but still not work.
then I remove libqglviewer-dev-qt5 and install libqglviewer-dev-qt4, not work neither. @CydKnocking
I have a question.
I have qmake4 and qmake5 both in my environment. does it influence qglviewer thing?
#50 @marctuscher

[cacadam89]

I am running into this same issue now, and the previously suggested fixes are not working. I am on Ubuntu 20.04.3 LTS, and when I try to install libqglviewer, the only options are libqglviewer2-qt5, libqglviewer-dev-qt5, libqglviewer-doc, and libqglviewer-headers. I have tried them all and none of this fixes my issues. I also tried @marctuscher's link (http://libqglviewer.com/download.html) to install from source and that didnt fix it either.

If this is only related to the visualization part, is there an easy way to change things so that I can still import g2o and use the optimization functionality w/o errors?

If anyone has any other suggestions, I would love to hear them!

[freesynapse]

Have the same problem. libqglviewer-dev and libsuitsparse-dev installed, build without errors. Import fails with /usr/lib/python3/dist-packages/g2o.cpython-38-x86_64-linux-gnu.so: undefined symbol: cs_di_schol.
Tried reinstalling almost every dependency without any luck. Also tried using manually installed QGLViewer.

[randomlylelo]

I had this same problem, solved by deleting g2opy folder, re-cloning it, but then do the change on #48 before building it. Afterwards, it just worked.

[Strohhut1]

My solution was the same as from @randomlylelo:

System: Ubuntu 20.04, Eigen3, python3.8

1. remove g2o folder
2. remove g2o.cpython-38-x86_64-linux-gnu.so file from /usr/lib/python3/dist-packages
3. clone g2o again
4. change g2opy/python/core/eigen_types.h according to Install on ubuntu 20.04 #48 or Quaterniond::w returns const double & instead of double to work with … #16 (I don't now which is better Quaterniond::w returns const double & instead of double to work with … #16 worked for me)
5. install libqglviewer from source (http://libqglviewer.com/download.html) and libqglviewer-dev-qt5 + libsuitesparse-dev with apt-get
6. follow build instructions

Let me know if it works for you too :)