[R] Fw: Plotting text-string real_date names at excel_date positions.

[Rex_Bryan@urscorp.com]

How do I post text-string dates along the x-axis instead of the excel_date
position values?

I would like to plot a time-series of chemical values changing with time
The first column is the internal date from excel.  This should be the x-axis
position of a graph
of the plotted data.

The second column is a text-string of date.  This should be what is posted
(instead of the excel_date).
The third column is the chemical data and this should be the position of a
point on the y-axis.
A line needs to connect the points but should break at the NA.

excel_date    real_date        chemical
36234        15-Mar-99        1.6
36302        22-May-99        0.195
36395        23-Aug-99        4.9
36475        11-Nov-99        NA
36593        8-Mar-00          3.58

Rex