For i loop, calling different dataframes

Question

I'm new to loops and I have a problem with calling variable from i'th data frame.

I'm able to call each data frame correctly, but when I should call a specified variable inside each data frame problems come:

Example:

for (i in 1:15) {
    assign(
      paste("model", i, sep = ""), 
    (lm(response ~ variable, data = eval(parse(text = paste("data", i, sep = "")))))
    )
    plot(data[i]$response, predict.lm(eval(parse(text = paste("model", i, sep = ""))))) #plot obs vs preds
}

Here I'm doing a simple one variable linear model 15 times, which works just fine. Problems come when I try to plot the results. How should I call data[i] response?

Answer 1

Let's say there are multiple dataframes with names: data1 ...data15 and that there are no other data-objects that begin with the letters: d,a,t,a. Lets also assume that in each of those dataframes are columns named 'response' and 'variable'. The this would gather the dataframes into a list and draw separate plots for the linear regression lines.

dlist <- lapply ( ls(patt='^data'), get)
lapply(dlist, function(df) 
                 plot(NA, xlim=range(df$variable), ylim=range(df$response)
                 abline( coef( lm(response ~ variable, data=df) ) )
         )

If you wanted to name the dataframes in that list, you could use your paste code to supply names:

names(dlist) <- paste("data", i, sep = "")

There are many other assignments you could make in the context of this loop, but you would need to describe the desired results better than with failed efforts.