How to use Python 3 by default?

[DiogoFerrari]

[domingoUnican]

Maybe what you can do is to create a pyenv for python 3. You can do it using the command pyvenv-create inside emacs.

[DiogoFerrari]

That does not work. I use a venv with python 3.6 and the only jupyter kernel for that ve is python3. But the ipython code blocks use python 2.7. (I am using Ubuntu and emacs 26)

[jkitchin]

This would by my approaches, in order of preference.

1. Install python3 so it is the system default.
2. Customize ob-ipython-command to launch a python3 version of ipython
3. Customize org-babel-python-command to launch the python3 of your choice
4. this doesnt' make it default, but you can use :python /path/to/python3 on a per python block basis I think, and probably set it as a generic header in the file..

[DiogoFerrari]

The only missing piece was the ob-ipython-command. Now it is working fine. Thank you!

An unrelated topic: I noticed a JSON error in the upstream version of ob-ipython see here caused by an unexpected error message in the shell. Maybe it will come up here, so it may be good to be aware of.

[DiogoFerrari]

... and as I predicted, the JSON error occurred. The problem is that any warning that happens in the shell command produces a JSON readtable error in the .org file. It happens when using #+INCLUDE:, for instance.

Setting ob-ipython-command to ipython3 does not help because it causes some warnings in the shell (with python 3.6.1), which results in JSON readtable error.

The solution I found was to let ob-ipython-comman to jupyter to use the jupyter console, but modify this function below to include the argument "--kernel=python3". It is a provisory solution, but make it possible to use ob-ipython (upstream version) in combination with your enhancements.

(defun ob-ipython--kernel-repl-cmd (name)
  (list ob-ipython-command "console" "--simple-prompt" "--existing" "--kernel=python3"
        (ob-ipython--kernel-file name)))

[jkitchin]

Can you give me mwe org file that causes the json warning? I never see this issue my self.

I saw your issue on ob-ipython. I am not sure what the best solution here is. It sounds like you have some shell interaction causing the problem. I don't see that here. I will be out for the next week, when I get back I will see if it seems to be a windows/linux issue.

[DiogoFerrari]

Here is a mwe:

#+TITLE:  title

#+INCLUDE: tmp2.org

* A section
#+BEGIN_SRC ipython :session tmp :exports both :results output
print("ok")
#+END_SRC

I am using

• Org mode version 9.0.9
• Ubuntu 18.04.2
• GNU Emacs 26.2 (build 2, x86_64-pc-linux-gnu, GTK+ Version 3.22.30)
• Python 3.6.8
• IPython 7.5.0
• Jupyter console 5.2.0
• ob-ipython here
• plus the two .el files you (@jkitchin) mention here

[roblem]

I have good experiences on scimax using anaconda python (rather than the system's python) and pyvenv on both Ubuntu and Fedora. I put this code in my user.el near the top:

;; pyvenv setup
(require 'pyvenv)
(setenv "WORKON_HOME" "~/anaconda/envs/")
(setq pyvenv-workon "python36")