Dear all,

I would like to solve a trivial problem (I guess it is) but can't find the right way. Maybe someone can help me ?

I've got a table with two factors (station = station ID, buffer = buffer size in meters) and a value for each unique combination of those two factors (S = number of habitats within each buffer around each station) like this:

TABLE 1

station buffer S

Abaia01 200 2
Abaia01 400 2
Abaia01 600 2
Abaia01 800 2
Abaia01 1000 2
Abaia01 1200 2
Abaia01 1400 2
Abaia01 1600 2
Abaia01 1800 2
Abaia01 2000 2
Abaia02 200 2
Abaia02 400 2
Abaia02 600 2
Abaia02 800 2
Abaia02 1000 2
Abaia02 1200 2
Abaia02 1400 2
Abaia02 1600 2
Abaia02 1800 3
Abaia02 2000 3


etc..

I would like to fill this more complete table here wich has a third factor "L5_code" (L5_code = type of habitat). As you can see, there are several types of habitats within each buffer around a station (up to several dozens).

TABLE 2

station buffer L5_CODE S

Abaia01 200 14 2
Abaia01 200 11 2

Abaia01 400 14 2
Abaia01 400 11 2


Abaia01 600 14 2
Abaia01 600 11 2


... ... ...


Abaia02 200 14 2
Abaia02 200 11 2


Abaia02 400 14 2
Abaia02 400 11 2


Abaia02 600 14 2
Abaia02 600 11 2　

I was hoping there was a simple function to do that but for now I've been useless with bad for loops, etc.

One method could be to go go through TABLE 1 step by step then fill TABLE 2 according to a combination of station and buffer of TABLE 1. I.e. go through the first column of TABLE 2 and find the corrseponding station name from TABLE 1, then go through the second column of TABLE 2 and find the corresponding buffer size from TABLE 1, then rep() the value of TABLE 1 in the column S of TABLE 2 corresponding to the right combination...

One other (quick) method would be to create a unique factor from the two first columns of TABLE 1 (station_buffer) but maybe there is something cleaner ? Do you have an idea ?

Thanks !

Mel

PS: those tables are supposed to be very large datasets of several thousands of rows.


___________________________________________________

Mélanie HAMEL
Institut de Recherche pour le Développement (I.R.D.)
U227 - CoRéUs (Biocomplexité des Ecosystèmes Coralliens de l'Indo-Pacifique)

Centre IRD - Nouméa
101 Promenade Roger Laroque
Anse Vata
BP A5 - 98848 Noumea
New Caledonia

Tel: 26 07 19
E-mail: melanie.hamel@ird.fr
Web: http://www.coreus.ird.fr

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