Chord diagrams in D3 are one of the more difficult chart types to produce from raw data. Fundamentally, you have to construct both a matrix and a mapping that explains how the matrix is composed and contains other meta data in order to render a complete diagram with appropriate coloring and labels. This separation between the data in matrix format and the meta data about the matrix makes it difficult to rapidly prototype diagrams from diverse data sources. Corresponding documentation can be found here.
Example Chord Diagrams in D3
clone the repo or download the zip file
cd into the directory
python -m SimpleHTTPServer 8080 (should be available on mac or use any local server)
go to localhost:8080 in your favorite browser (if your favorite is not IE)