Question

I created some dataframes on the fly to hold some data on gas prices:

for(i in 1995:2007) {
   assign(paste("gas_data_", i, sep=""), 
          read.csv(paste("NaturalGasCash", i, ".txt", sep="")))
}

Now I need to create new variables to hold just one column of this dataframes but I don’t know how to do this, I tried:

for(i in 1995:2007){
   assign(paste("yields_data_", i, sep=""), 
          as.value(paste("yields_data_", i, "$X6Mo", sep="")))
}

But now it just creates a variable with a string in it.

Answer 1

Some (untested) example code illustrating my comment above:

#Store all data frames in a list
f <- paste0("NaturalGasCrash",1995:2007,".txt")
df_list <- lapply(f,read.csv)
names(df_list) <- paste0("gas_data_",1995:2007)

#Get just one of the data frames
df_list[["gas_data_2001"]]

#Get just a particular column from each
col <- lapply(df_list,'[[',"X6mo")