[R] Automated Regressions

B77S bps0002 at auburn.edu
Mon Dec 12 19:42:26 CET 2011

I don't know why you had "c in a(1:2000))"  
c is a function see ?c ...
and you want "a" (the row number in SQL_Code) to change with each iteration
in the loop.

Perhaps this might work (I'm not saying this is the best option, just a
potential fix for what you have): 

for (a in 1:2000) {
Dataset <- sqlQuery(Database, SQL_Code[a,1])
print(summary(lm(Quant~ UPE + Mon, data = Dataset)))

ryanSt wrote
> Hello R-Experts,
> I've got a question, concerning the automation of a number of regressions
> (lm) with the help of a loop (for i in ....).
> The situation is as follows (the code follows after that):
> I have my data in an access database. I have historical data for 2000
> parts, for each of this parts I want to do a regression analysis, so I
> need to do 2000 regressions (just for one country, there are also more
> countries). So this would be a lot of manual effort. 
> What I want to do is to automate this routine. I have already established
> a database connection via RODBC.
> So I can acces every part with its distinct code by a SQL Query. For every
> part, the SQL Query has to be adapted for the parts name.
> My idea was to generate the SQL Code in Excel for ervery part and save
> this as an txt-file. So I can define the SQL-Codes as an object (SQL_Code
> <- load.table("...txt, header = FALSE). 
> In the next step I can build a loop, which tells R to go through the
> object SQL_Code line for line, using the text for the SQL Query.
> The code is as follows:
> SQL Code in the sqlparts.txt. file: "SELECT table.* FROM table WHERE
> ((table.part) = '2929AAD766')" (2000 lines for all parts, each part has a
> distinct code)
> SQL_Code <- load.table("sqlparts.txt", header = FALSE)
> Loop: 
> for (c in a(1:2000)) {
> Dataset <- sqlQuery(Database, SQL_Code[a,1])
> print(summary(lm(Quant~ UPE + Mon, data = Dataset)))
> }
> Unfortunately, this loop doesn't work. I think, it's because R does not
> interpret the object SQL_Code as text, so the sqlQuery is incomplete.
> Can anybody help me with that problem?
> Thank you in advance.
> Greets
> Ryan

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