I want to plot data using GChart that has regular hourly, half-hourly
and
one-minute time points, with significant data shifts plotted in
between the
regular times.

For instance:

X (time)       Y (value)
28/01:00pm 15.5
28/12:30pm 15.4
28/12:00pm 14.7
28/11:30am 14.0
28/11:00am 14.3
28/10:30am 11.9
28/10:12am 13.7
28/10:00am 14.4
28/09:30am 12.4
28/09:00am 11.7
28/08:30am 11.2
28/08:00am 12.9
28/07:30am 12.9
28/07:00am 11.4
28/06:30am 12.5
28/06:00am 11.6
28/05:30am 12.8
28/05:00am 12.2
28/04:46am 12.5
28/04:24am 13.0
28/04:11am 12.9
28/03:51am 12.9
28/03:30am 12.9
28/03:00am 13.0

Two schemes that are used in other software are:

(1) Excel:

http://blogs.msdn.com/excel/archive/2007/12/17/intraday-time-series-c...

where each day is expressed as a whole floating point number, with
each time of day
expressed as a fraction of that day number.

(2) GNUPLOT

http://www.gnuplot.info/docs/node76.html#1408

where time is expressed as seconds since 2000.

Any suggestions would be most welcome!

Mal.