[R] Plotting activity by time and dates

[Neotropical bat risk assessments]

Hi all,

As I understand the zoo package will aggregate dates and times, but 
unclear how to tackle this problem.

I need to accomplish the following:

1. Generate a scatter plot of bat activity with dates on the X-axis 
and time on the Y-axis.
include sunset and sunrise curves as an added part of graphic.

In Excel I have a kludged way to do this, but it is not exactly what 
I need and the times on the Y axis do not display correctly due to 
the 24:00 roll over to next date and would prefer to understand how 
to do this using R so I can repeat it with multiple data sets for 
multiple locations.
I removed the Graphic display as apparently the server refused the 
massage with it.
I can email directly if anyone is able to assist or wished to see it.

A sample of the data format is below.
Any suggestion welcome.

Tnx.

The bat activity data is in the format below with the species name, 
date and time the species was active.

Spec_code       Date    Time
Eptfus          6/4/03  22:44
Eptfus          6/4/03  22:44
Eptfus          6/9/03  21:59
Eptfus          6/10/03 3:24
Eptfus          6/13/03 0:22
Eptfus          6/13/03 3:24
Eptfus          6/17/03 0:03
Eptfus          6/17/03 2:43
Eptfus          6/17/03 21:59



The sunset-Sunrise data seen below is also straight forward:
  Date   Rise    Set
6/1/2003        4:12    19:50
6/2/2003        4:11    19:51
6/3/2003        4:10    19:52
6/4/2003        4:10    19:53
6/5/2003        4:09    19:54
6/6/2003        4:09    19:54
6/7/2003        4:09    19:55
6/8/2003        4:08    19:56
6/9/2003        4:08    19:57
6/10/2003       4:08    19:57
6/11/2003       4:07    19:58
6/12/2003       4:07    19:58
6/13/2003       4:07    19:59
6/14/2003       4:07    19:59
6/15/2003       4:07    20:00
6/16/2003       4:07    20:00
6/17/2003       4:07    20:01
6/18/2003       4:07    20:01