A lot of people do "Hello World !" to discover a language, some prefers doing financial data tools instead.
yf is for Yahoo Finance and script because it's a script and I have a damn lack of immagination to find a name.
yf_script is my first ruby project and it's about scrapping data from Yahoo! Finance and use it with a lot of tools (RSI, Stochastic, bollinger bands, etc) The final purpose is to make a script wich can be used to manage portfolio or format information for further use (in Excel, R, backtest a trading algo, etc)
Well, it's my first ruby script and to learn ruby, I wanted to do something I like and I need to make sure I go to through. And I used yahoo finance API because you can use it with any language while this language can use a network. The documentation is pretty clear and the availability is close to 100%. I know it's delayed for most of stocks and you can't get historical intraday data but it's free of cost and registration.
Honnestly, me and maybe other peoples But if you're interrested in financial market, and you need a script to quickly prepare a spreadsheet, I think you should take a look at this (when it'll be finished) I know, it's ugly, it's in a terminal and there is only text, but if you want to add a GUI, please fork this repo and send a pull request when you're done, I'll merge if it looks good. (Yes, I hate doing GUIs, I love back-end)
NB : It's Ruby (it's not as fast as C) and Yahoo's delayed data, so if I add a trading algo feature, it's only for demonstration purpose.