R help - Aug 2010 - Question regarding S4 objects and reading in excel data with RODBC

L.S.

I am trying to get data from an excel sheet using the RODBC library, quite
like the example on page 34 of the 'Data manipulation with R' book
written
by Phil Spector. It seems very straightforward, yet I get the same error
everytime I try it, with different excel sheets and trying to tweek the code
a bit. This is what I do:

library(RODBC)

sheet='X:\\example.xls'
con=odbcConnectExcel(sheet)

tbls=sqlTables(con)
tbls$TABLE_NAME
qry=paste("SELECT * FROM '",tbls at
TABLE_NAME[1],"'", sep=" ")


The error I get is:
Error in paste("SELECT * FROM '", tbls at TABLE_NAME[1],
"'", sep = " ") :
  trying to get slot "TABLE_NAME" from an object (class
"data.frame") that
is not an S4 object

Does anyone know what I'm doing wrong here? I have to admit that I don't
know much about sql.


Best regards,

Sander van Kuijk
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On 04/08/2010 5:38 AM, Sander wrote:
> L.S.
> 
> I am trying to get data from an excel sheet using the RODBC library, quite
> like the example on page 34 of the 'Data manipulation with R' book
written
> by Phil Spector. It seems very straightforward, yet I get the same error
> everytime I try it, with different excel sheets and trying to tweek the
code
> a bit. This is what I do:
> 
> library(RODBC)
> 
> sheet='X:\\example.xls'
> con=odbcConnectExcel(sheet)
> 
> tbls=sqlTables(con)
> tbls$TABLE_NAME
> qry=paste("SELECT * FROM '",tbls at
TABLE_NAME[1],"'", sep=" ")
> 
> 
> The error I get is:
> Error in paste("SELECT * FROM '", tbls at TABLE_NAME[1],
"'", sep = " ") :
>   trying to get slot "TABLE_NAME" from an object (class
"data.frame") that
> is not an S4 object
tbls is not an S4 object, so you can't use the @ notation with it.  In 
some older versions of R @ would extract an attribute (because that's 
where S4 slots were stored), but current versions don't allow this. 
Without testing, I would guess you can replace

tbls at TABLE_NAME[1]

with

attr(tbls, "TABLE_NAME")[1]

but it's possible the name is wrong.

Duncan Murdoch
> 
> Does anyone know what I'm doing wrong here? I have to admit that I
don't
> know much about sql.
> 
> 
> Best regards,
> 
> Sander van Kuijk