For scientific computing and machine learning Python is quite big, but it is all 2.x.<p>Moreover, many people in the scientific community applying machine learning are biologists, neuroscientists, physicists and linguists. These people are NOT experience developers. These are experienced scientists.<p>What is needed for these people to move to 3.x is mostly adequate library support and a good reason. Many of these will have a hard time understanding why they can't just write print "string" anymore.