[R] Times series adjustment

[Poizot Emmanuel]

Dear all,

I want make correction depth of a bathymetric data set.
To do so, I have the depth data set sample every second (a depth at each 
second) in one hand, and in the other hand, I have a tide variation 
level data set sample every 250 ms. The time register in each data sets 
(tide and bathymetric) is express in seconds followinf this format : 
hh:mm:ss.ss
I would like to rectify the depth (bathymetry) by substrating the tide 
at each depth time.
I tried to construct time series using pastecs package but didn't succed

Example of the tide data set:
Time             Correction
11:55:07.58  -2.64
11:55:07.68  -2.64
11:55:07.88  -2.64
11:55:08.28  -2.64
11:55:08.38  -2.64

Example of the bathymetric data:
X                Y             Date       Time              Depth
-2.620748 48.75121 01/00/00 12:07:16.000 -25.6
-2.620714 48.75121 01/00/00 12:07:17.000 -25.8
-2.620698 48.75121 01/00/00 12:07:17.000 -26.0
-2.620682 48.75121 01/00/00 12:07:18.000 -26.1
-2.620667 48.75121 01/00/00 12:07:18.000 -26.1

How can I construct the time series based on that two data sets allowing 
me then to to the depth rectification ?
Regards

-- 
Cordialement

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Emmanuel Poizot
Cnam/Intechmer
B.P. 324
50103 Cherbourg Cedex

Phone (Direct) : (00 33)(0)233887342
Fax : (00 33)(0)233887339
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