Gfilui

This Youtube link helped me to install it.

The steps are:

sudo apt-get install libssl-dev openssl
wget https://www.python.org/ftp/python/3.5.0/Python-3.5.0.tgz
tar xzvf Python-3.5.0.tgz
cd Python-3.5.0
./configure
make
sudo make install

To check if python is installed type python3.5 else:

sudo ln -fs /opt/Python-3.5.0/Python /usr/bin/python3.5

Just follow those steps (tested) :

Step 1 – Install Required Packages

Use the following command to install prerequisites for Python before installing it.

sudo apt-get install build-essential checkinstall
sudo apt-get install libreadline-gplv2-dev libncursesw5-dev libssl-dev libsqlite3-dev tk-dev libgdbm-dev libc6-dev libbz2-dev

Step 2 – Download Python 3.5.2

Download Python using following command from python official site. You can also download latest version in place of specified below.

cd /usr/src
sudo wget https://www.python.org/ftp/python/3.5.2/Python-3.5.2.tgz

Now extract the downloaded package.

sudo tar xzf Python-3.5.2.tgz

Step 3 – Compile Python Source

Use below set of commands to compile python source code on your system using altinstall.

cd Python-3.5.2
sudo ./configure
sudo make altinstall

make altinstall is used to prevent replacing the default python binary file /usr/bin/python.

Step 4 – Check the Python Version

Check the latest version installed of python using below command.

$ python3.5 -V

Python 3.5.2

Source.

As far as I can tell, at least in a docker container, one can definitively apt-get python 3.

First I ran into a ubuntu container with container:

docker run -it --rm ubuntu:latest bash

then for some reason it needed to update some ubuntu stuff so I did (inside the container):

apt-get update && apt-get install -y build-essential git libjpeg-dev

and then I simply installed python3 and it seems it automatically got python 3.5:

apt-get install python3
apt-get install python3-pip

and to test if pip works lets download something:

pip3 install tensorflow

all seems to work fine for me.

Important Note: it seems that if you already have python 3.4 installed then apt-get install python3 does not work because it says you already have it. It seems that was one of my problems because I was starting from a docker image from tensorflow (in particular gcr.io/tensorflow/tensorflow:latest-devel-py3) and something in that image (I assume its that they already have python 3.4 but it might something else) didn't allow me to update my python to get python 3.5.

credit: I discovered this when I asked the following: https://stackoverflow.com/questions/42122826/can-one-use-python-3-5-in-a-docker-container-based-out-of-the-tensorflow-docker

Note: one can also just install Anaconda. For a docker example one can do:

docker pull continuumio/anaconda3
docker run -i -t continuumio/anaconda3 /bin/bash

from their official website: https://hub.docker.com/r/continuumio/anaconda3/

This solution installs python 3.6 but I am sure if you look into it there you can get python 3.5 if thats what you want.

Note: you should probably be using a virtual environment like virtual env or conda/anaconda anyway unless your using docker anyway. Just wanted to remind people.

There are a number of newer python distributions available to install via apt-get listed in Ubuntu Packages

as an example the following versions are currently available:

python2.7

python3.2

python3.4

python3.5

python3.6

Availability varies with Ubuntu release to a degree. For example 3.5 is available for Xenial, Yakkety, and Zesty and 3.6 is available for Yakkety and Zesty but you must enable the Universe repository if not enabled to obtain them via apt-get. To check availability for your version of Ubuntu check the links above.

A quick peek indicates that this answer is also still valid as that PPA has 3.6 even for Trusty.

I would consider using virtual environments instead of installing python versions via apt-get.

Using virtual environments, see here, are a good practice for developing with python. They let you isolate your python environment from the system installed python versions.

In addition you don't have to get sudo access while installing any library (via pip etc.).

Conda is actively updated and allows you to install multiple python versions in managed venvs without the tedium of setting it all up yourself. Binary extension pathing problems may have been solved in many of the anaconda managed dependency/pip chains it uses.

On Ubuntu 16.04.1 LTS you have both python 2 (python), and python3 already installed.

To update theme to the latest version, you can proceed as follows:


1- Update the package list and upgrade all your system software to the latest version available

sudo apt update && sudo apt -y upgrade

2- install python-pip and python3-pip (alternative Python package installer) from Ubuntu repositories

sudo apt install python-pip
sudo apt install python3-pip

2'- check the vesrions

pip -V; pip3 -V

3- upgrade pip (The PyPA recommended tool for installing Python packages) to the last version in PyPI (the Python Package Index)

sudo -H pip3 install --upgrade pip 
sudo -H pip install --upgrade pip

3'- check the vesrions

pip -V; pip3 -V

you should get an output similar to:

pip 9.0.1 from /usr/local/lib/python2.7/dist-packages (python 2.7)
pip 9.0.1 from /usr/local/lib/python3.5/dist-packages (python 3.5)

4- (optionally) To be able to use a python subversion per project/application, and keep the dependencies required by different projects separated. you need to install Virtualenv

[sudo -H] pip install virtualenv