Rbind dataframes using wildcard

Question

Suppose I have three dataframes called A1-pre, B3-pos, B4-pre and I want to merge these dataframes. The columns have the same name, so I can use rbind.

newdf <- rbind(A1-pre, B3-pos, B4-pre)  #this would work

However, I do not want to manually input all the names of the dataframes myself, I rather use a wildcard for that, so something like

newdf <- rbind(grep(-)) #but this does not work

Any idea how I could do that? Or even better, matching any dataframe named "pre" or "pos" and rbind them all.

Answer 1

You can do it with get() and ls():

'A1-pre' <- matrix(rnorm(100), 5) 
'B3-pos' <- matrix(rnorm(100), 5)
'B4-pre' <- matrix(rnorm(100), 5)
'C5-not' <- matrix(rnorm(100), 5)

names <- grep('pre|pos$', ls(), value=T)

newDF <- mapply(get, grep('pre|pos$', ls(), value=T))