On Apr 20, 2009, at 8:04 PM, Katharina May wrote:
Hi there,
I've got a database or rather spreadsheet with several columns and
rows.
For one column named sites I want to loop through all possible
values and retrieve
all data out of the database where site = x and write it into an
object named 'sitex_data'.
Somehow I'm really missing something as I'm not able to create these
sitex_data objects with
the database values, neither using list nor assign...
Here some code snipplets:
>library (RODBC)
>channel <- odbcConnectExcel2007 ("biomass_data.xlsx")
>site_data <- sqlQuery(channel, "select site_no from [biomass_data
$] group by site_no")
#Here the values I want to loop through
>str(site_data)
'data.frame': 44 obs. of 1 variable:
$ site_no: num 4 7 9 10 15 16 17 18 19 20 ...
#Here my first try [error message on the line within the loop,
saying something like:
# 'recursive indexing on level 2 failed']
sites_object_list <- vector("list",99)
for(i in site_data) {
sites_object_list[[i]] <- sqlQuery(channel, paste("select * from
[biomass_data$] where site_no = ",i,sep=""))
}
This does not appear to be a dataset to which we have access, so I
will take an untested stab at this. What happens if you assign the
results of the function unique() around site_data$site_no to your
index, i? That way you would stand a chance of referring to the sites
in a manner that R might understand and to only use the site numbers
once apiece in the loop. I'm not a competent SQL programmer so i have
no comments on that part.
David Winsemius, MD
Heritage Laboratories
West Hartford, CT
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