Once we know which queries to execute for getting the facets and hierarchical information, we need a graphical representation of the same. There are a few open source graph engines, mostly JavaScript based, that can be used for this. Most of these engines take JSON data and use it to display the graphs. Let us see some of the engines:
chart.js: This is an HTML5 based graph engine. It can be downloaded from http://www.chartjs.org.
D3.js: This is another JavaScript library that brings data to life using HTML and CSS. D3 can be used to generate an HTML table from an array of numbers or the same numbers can be used to draw an interactive bar chart. It is available for download at http://d3js.org.
Google charts: This is another library provided by Google. It can be used to draw graphs based on data from Solr. Google charts provide a large range of graphs from simple line charts to complex hierarchical tree maps. Most of the charts are ready to use. Google charts can be downloaded...