R help - May 2009 - Problems with 'valid columns' when using merge

Dear all,

I am trying to use 'merge' within a loop, however, I receive an error
relating to the 'by' argument of the command, as follows:
> merge_year <- 1986
> 
> for (i in 1:10) { # Number of file pairs
+     assign(paste("merged_arunfek_", merge_year, sep=""),
merge(x=paste("arunoff_",start_arunoff, sep=""),
y=paste("fekete_", start_fekete, sep=""),
by=c("Latitude", "Longitude"), sort=FALSE))
+     attach(paste("merged_arunfek_", merge_year))
+     merge_year = merge_year+1
+     }
Error in fix.by(by.x, x) : 'by' must specify valid column(s)


However, as far as I can tell, the column names (as stated in the above code)
appear to be valid:

> colnames(arun_1986)
[1] "Latitude"  "Longitude" "Sim_1986"
> colnames(fekete_1986)
[1] "Latitude"  "Longitude" "X1986"


I'm trying to merge based on both the Latitude and Longitude column and have
used by=c("name_x", "name_y") before without too many
problems. Any suggestions would be gratefully received.

Many thanks,

Steve

Your parameters to merge do not appear to be objects; they are strings,  You
might want to try:

merge(x=get(paste("arunoff_",start_arunoff, sep="")),
y........

You might want to consider a 'list' for storing your data.  Also are you
ever 'detach'ing?  It is useful to find ways to avoid 'attach'
(IMHO).

On Fri, May 1, 2009 at 8:51 AM, Steve Murray <smurray444@hotmail.com>
wrote:
>
> Dear all,
>
> I am trying to use 'merge' within a loop, however, I receive an
error
> relating to the 'by' argument of the command, as follows:
>
> > merge_year <- 1986
> >
> > for (i in 1:10) { # Number of file pairs
> +     assign(paste("merged_arunfek_", merge_year,
sep=""),
> merge(x=paste("arunoff_",start_arunoff, sep=""),
y=paste("fekete_",
> start_fekete, sep=""), by=c("Latitude",
"Longitude"), sort=FALSE))
> +     attach(paste("merged_arunfek_", merge_year))
> +     merge_year = merge_year+1
> +     }
> Error in fix.by(by.x, x) : 'by' must specify valid column(s)
>
>
> However, as far as I can tell, the column names (as stated in the above
> code) appear to be valid:
>
>
> > colnames(arun_1986)
> [1] "Latitude"  "Longitude" "Sim_1986"
> > colnames(fekete_1986)
> [1] "Latitude"  "Longitude" "X1986"
>
>
> I'm trying to merge based on both the Latitude and Longitude column and
> have used by=c("name_x", "name_y") before without too
many problems. Any
> suggestions would be gratefully received.
>
> Many thanks,
>
> Steve
>
> ______________________________________________
> R-help@r-project.org mailing list
> https://stat.ethz.ch/mailman/listinfo/r-help
> PLEASE do read the posting guide
>
http://www.R-project.org/posting-guide.html<http://www.r-project.org/posting-guide.html>
> and provide commented, minimal, self-contained, reproducible code.
>


-- 
Jim Holtman
Cincinnati, OH
+1 513 646 9390

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