Bokeh timedelta axis formatting, showing just the parts of 00h00m00s necessary.

bokeh_td.py

def timedelta_xaxis(f):
    """Expects the axis to be in millis"""
    f.xaxis.ticker = bom.tickers.DatetimeTicker()
    f.xaxis.formatter = bom.FuncTickFormatter(code="""
        // TODO: Add support for millis

        // Calculate the hours, mins and seconds
        var s = Math.floor(tick / 1e3);
        
        var m = Math.floor(s/60);
        var s = s - 60*m;
        
        var h = Math.floor(m/60);
        var m = m - 60*h;
        
        var h = h.toString();
        var m = m.toString();
        var s = s.toString();
        var pm = m.padStart(2, "0");
        var ps = s.padStart(2, "0");

        // Figure out what the min resolution is going to be
        var min_diff = Infinity;
        for (var i = 0; i < ticks.length-1; i++) {
            min_diff = Math.min(min_diff, ticks[i+1]-ticks[i]);
        }

        if (min_diff <= 60e3) {
            var min_res = 2;
        } else if (min_diff <= 3600e3) {
            var min_res = 1;
        } else {
            var min_res = 0;
        }

        // Figure out what the max resolution is going to be
        if (ticks.length > 1) {
            var max_diff = ticks[ticks.length-1] - ticks[0];
        } else {
            var max_diff = Infinity;
        }

        if (max_diff >= 3600e3) {
            var max_res = 0;
        } else if (max_diff >= 60e3) {
            var max_res = 1;
        } else {
            var max_res = 2;
        }

        // Format the timedelta. Finally.
        console.log(min_diff, max_diff, min_res, max_res);
        if ((max_res == 0) && (min_res == 0)) {
            return `${h}h`;
        } else if ((max_res == 0) && (min_res == 1)) {
            return `${h}h${pm}`;
        } else if ((max_res == 0) && (min_res == 2)) {
            return `${h}h${pm}m${ps}`;
        } else if ((max_res == 1) && (min_res == 1)) {
            return `${m}m`;
        } else if ((max_res == 1) && (min_res == 2)) {
            return `${m}m${ps}`;
        } else if ((max_res == 2) && (min_res == 2)) {
            return `${s}s`;
        }
    """)