R help - Jan 2010 - data frame names in sequence

I've been stuck with this problem for a whole afternoon. It's silly but
totally pissed me off. I have a set of data frames with names in a sequence:
df_1, df_2, df_3, ..., df_20. Now I want to access each data frame (read or
write) in a for loop, in a way something like this:

for (i in 1:20) {
  df_i <- ######
  length(which(df_i[,7]==1))
  ######
}

I tried paste or cat ("df_", i, sep=""). But neither way
works. Your help is
highly appreciated!! Thanks in advance!
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Zoho wrote:
> 
> I've been stuck with this problem for a whole afternoon. It's silly
but
> totally pissed me off. I have a set of data frames with names in a
> sequence: df_1, df_2, df_3, ..., df_20. Now I want to access each data
> frame (read or write) in a for loop, in a way something like this:
> 
> for (i in 1:20) {
>   df_i <- ######
>   length(which(df_i[,7]==1))
>   ######
> }
> 
> I tried paste or cat ("df_", i, sep=""). But neither
way works. Your help
> is highly appreciated!! Thanks in advance!
> 
df_1 <- data.frame(x1=3,x2=5)
df_2 <- data.frame(x1=2,x2=7)
df_3 <- data.frame(x1=-1,x2=1)

for(k in 1:3){v <- paste("df_",k,sep=""); print(get(v))}
for(k in 1:3){v <- paste("df",k,sep="_");
print(get(v)[,2])}

Have a look at get:

?get

Berend
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?get


for (i in 1:20) {
 df_i <- get(paste('df_', i, sep=''))
 length(which(df_i[,7]==1))
 ######
}

On Sat, Jan 9, 2010 at 7:57 PM, Zoho <ynpjf2@gmail.com> wrote:
>
> I've been stuck with this problem for a whole afternoon. It's silly
but
> totally pissed me off. I have a set of data frames with names in a
> sequence:
> df_1, df_2, df_3, ..., df_20. Now I want to access each data frame (read or
> write) in a for loop, in a way something like this:
>
> for (i in 1:20) {
>  df_i <- ######
>  length(which(df_i[,7]==1))
>  ######
> }
>
> I tried paste or cat ("df_", i, sep=""). But neither
way works. Your help
> is
> highly appreciated!! Thanks in advance!
> --
> View this message in context:
> http://n4.nabble.com/data-frame-names-in-sequence-tp1010518p1010518.html
> Sent from the R help mailing list archive at Nabble.com.
>
> ______________________________________________
> 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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