Generating a Gantt chart from HJSON input

This blog post is a slight departure from the normal topics here. Worry not, we’ll return to discussing Verilog, Chisel, and low-level software work soon. I wrote a quick script to help serve a need (producing a Gantt chart) and thought perhaps others would find it useful.

There are a wide range of online services to help produce and maintain Gantt charts, but none quite offered what I was looking for. I want something open source, easy to use, and where the underlying data is human readable and can be version controlled. The python-gantt library formed an excellent starting point for generating a Gantt chart in SVG, but I thought it was worth trying to support a slightly less verbose input format.

Enter hjson, which aims to be a superset of json with much more forgiving syntax. This has its disadvantages, but it does seem to work well as a concise and easy to edit data format. A quick python script to parse an hjson input to produce a Gantt chart and we’re away. One feature I do like is the use of fuzzy matching for project references and dependencies. Again, this makes it easy to hack on by hand. In the example below, I’m able to use “mftr widgets” to refer to the “Manufacture widgets” task.

Example input:

    {
        projects: [
            {
                name: Project Alpha
                color: green
            }
        ]

        tasks: [
            {
                name: Design widget
                begin: 2016-10-14
                duration: 7,
                people: Farquaad
                project: alpha
            }
            {
                name: Set up widget production line
                begin: 2016-10-19
                duration: 6
                people: Zack
                project: alpha
            }
            {
                name: Manufacture widgets
                duration: 7
                people: Carrie
                deps: ["design widget", "widget prod line"]
                project: alpha
            }
        ]

        milestones: [
            {
                name: Widgets start shipping
                start: 2016-10-30
                deps: ["mftr widgets"]
                project: alpha
            }
        ]
    }

Example output (./hjson_to_gantt --begin-date 2016-10-10 --end-date 2016-11-13 example.hjson --name example):

hjson_to_gantt is available on Github.

Alex Bradbury