AFAIK, Ruby doesn't have anything like Python's numpy. There has been some effort to fix that, but not one driven by necessity or an organized movement: https://github.com/SciRuby/sciruby/wiki/The-SciRuby-Manifest...

Fun bit of trivia: Hadley Wickham (of R's ggplot2 and dplyr fame, among many other things) said that if R hadn't been around when he first got into statistical programming, Ruby would have been his next choice, because of Ruby on Rails. He says now, his choice would be Python or Julia ("or maybe JavaScript"):

https://www.reddit.com/r/dataisbeautiful/comments/3mp9r7/im_...

Fun to imagine ggplot2 in R...or as a competitor to D3 in data visualization.