Does anyone know of a Linux equivalent to tableau?

Hi, I'm a linux hobbyist who has tinkered with postgis and apache to manipulate data for display in QGis and as tables and charts using apache. - I like to think I have a reasonable knowledge of databases but don't do it all day every day ;) I have recently been introduced to Tableau (https://www.tableau.com) which operates on Windows and on Mac clients. It seems to me to be a GUI for what I do with Postgis and apache (with a bit of R functionality added - Learning R is on my 'to do' list) Does anyone know about tableau, and whether there is a FOSS equivalent? I am on and off line at the moment, so may be slow to respond to comments. With thanks