Creating Graphics for BI Reports in Ruby on Rails

So your manager wants reports with sexy graphs – what are your options and what are the pros and cons

I have found eight usable packages with different considerations

OpenFlashChart

This is a series of libraries including one for Ruby that allow the generation of great looking charts that are very dynamic (see the demo on the website). Data is easily passed via JSON making it easy to integrate. The only downside is that it requires the client to have an Adobe Flash player installed. This is common enough for it not to be a problem for most people but it does limit the portability. Also as it generates a flash object rather than a JPGPNG or GIF it means that this is suitable for online output but not useful in RSS feeds etc and when printed all the dynamic features are lost anyway.

Gruff

Gruff provides a simple and easy to use Ruby package that works well with Rails. It does require that ImageMagick/RMagick is installed on the server (HowTo for OSX) and this can be a pain for some people. The advantage is that it produces good looking, native SVG, PNG, JPG, GIF files so they are easily portable and printable

Scruffy

Scruffy is very similar to Gruff although appears to be less well used and not recently updated. It too requires ImageMagick/RMagick installed and whilst it is based on SVG is capable of producing other graph formats.

Sparklines

Sparklines are small graphs that are usually embedded within the text of a paragraph or placed inside tables. The standard output is a png file and it also requires ImageMagick/RMagick to be installed. This size of the graphs makes it useful for small graphs such as indicators rather than main report graphics.

gchartrb & Google Charts
See also http://www.infoq.com/articles/bass-google-charts-gchartrb

Google charts provide perhaps the easiest interface to creating a graph. All the parameters get bundled up in the URL and Google does all the work. Added to this is gchartrb that provides an easy and intuitive way to build the URL. All this means that there is nothing to install on the server side however it also means that to get access to your image you have to be connected to the internet and pass data which your company may regard as secure to the Google servers. This may make it impractical for use with BI data.

SVG::Graph

SVG:::Graph is a pure Ruby library for generating charts, which are a type of graph where the values of one axis are not scalar. The output is an SVG which might not be supported in all browsers or a PNG file

Flot

Flot is a pure Javascript plotting library for jQuery. It produces graphical plots of arbitrary datasets on-the-fly client-side. The package once again takes a JSON string as input and produces great looking graphs that can be dynamically updated

CSS Graph Helper

A Ruby on Rails helper for making simple graphs. The graphs use only CSS/HTML (and an optional gradient image). Great at creating quick simple online graphs but very limited in its capabilities

So:
If you are looking for a simple graph that is easy to generate then gchartrb is for you
If you are looking for dynamic and very attractive content then Flot or OpenFlashChart are your options
If you are looking for small KPI indicator type graphs consider Sparklines
If you are looking for good looking images that can be distributed consider Gruff, Scruffy and SVG::Graph
If you are happy with a quick and easy CSS based solution then look at CSS Graph Helper

This article was originally published on BIonRails, another Data Management & Warehousing website

Leave a Reply

Your email address will not be published.

This site uses Akismet to reduce spam. Learn how your comment data is processed.