R help - May 2005 - reading multiple files

Dear All,


How do I read in multiple data frames or matrices in a
loop, e.g.

for (i in 1:n) {
   channel <- odbcConnectExcel("filenames")
   file[i] <- as.data.frame(sqlFetch(channel,
"sheet"))
}

I would like file[i] to be the name of the data.frame
(i.e. file[1], file[2], file[3],...etc) rather than a
vector.

Thanks in advance for any help.

Dave

You're almost there, use a list:
myfiles <- list()
for (i in 1:n) myfiles[[i]] <- etc
You can then get at your data frames with myfiles[[1]],
myfiles[[2]]... Or, if you prefer to combine them into a single data
frame (assuming they're similar),
allmyfiles <- do.call("rbind",myfiles)


-----Original Message-----
From: Dave Evens [mailto:devens8765 at yahoo.com]
Sent: Tuesday, May 24, 2005 11:10 AM
To: r-help at stat.math.ethz.ch
Subject: [R] reading multiple files



Dear All,


How do I read in multiple data frames or matrices in a
loop, e.g.

for (i in 1:n) {
   channel <- odbcConnectExcel("filenames")
   file[i] <- as.data.frame(sqlFetch(channel,
"sheet"))
}

I would like file[i] to be the name of the data.frame
(i.e. file[1], file[2], file[3],...etc) rather than a
vector.

Thanks in advance for any help.

Dave

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Dave Evens wrote:
> Dear All,
> 
> 
> How do I read in multiple data frames or matrices in a
> loop, e.g.
> 
> for (i in 1:n) {
>    channel <- odbcConnectExcel("filenames")
>    file[i] <- as.data.frame(sqlFetch(channel,
> "sheet"))
> }
> 
> I would like file[i] to be the name of the data.frame
> (i.e. file[1], file[2], file[3],...etc) rather than a
> vector.
The terminology you are using re. R objects seems to be rather confused.

Quite probably you want a list of data frames such as using the 
filenames as names for the list elements along the follwoing lines:

library(RODBC)
dataframes <- vector(mode="list", length=length(filenames))
names(dataframes) <- filenames
for(i in filenames){
   channel <- odbcConnectExcel(i)
   dataframes[[i]] <- sqlFetch(channel, "sheet")
   close(channel)
}


Uwe Ligges


> Thanks in advance for any help.
> 
> Dave
> 
> ______________________________________________
> R-help at stat.math.ethz.ch mailing list
> https://stat.ethz.ch/mailman/listinfo/r-help
> PLEASE do read the posting guide!
http://www.R-project.org/posting-guide.html