How to create a data frame from multiple vectors?

Question

I have 8 vectors with the same pattern in their names: T.vec_1, T.vec_2, ..., T.vec_8. They are all of the same length. Now I want to create a data frame that consists of those 8 vectors.

Of course there is this option, which is not very elegant and does not make sense if there is a higher number of vectors:

df <- data.frame(T.vec_1, T.vec_2, T.vec_3, T.vec_4, T.vec_5, T.vec_6, T.vec_7, T.vec_8)

That is why I tried to do it by using a loop in two ways, which both did not work out:

for (i in 1:8) {
  df <- data.frame(get(paste("T.vec_", i, sep = "")))
}

and

for (i in 1:8) {
  assign(df), data.frame(get(paste("T.vec_",i,sep="")))
}

What is the proper and smart way to do it?

`cbind`? I think you just want to "bind" them by "c"olumns, right? — cory, Sep 11 '20 at 11:51
How you created the vectors? Eventually at that point you can use a list. — jogo, Sep 11 '20 at 11:55
I created the vectors by using assign in a for loop: `for (i in 1:8) { assign(paste0("T.slice_", i), T.array[,,i]) assign(paste0("T.vec_", i), as.vector(get(paste("T.slice_",i, sep="")))) assign(paste0("WRFdf_", i), data.frame(cbind(lonlat,get(paste("T.vec_",i, sep=""))))) }` Would there be a possibility to use a list at some point? — climsaver, Sep 11 '20 at 12:04
yes, e.g. `sapply(1:8, function(i) as.vector(T.array[,,i]))` - this will put the vectors in a matrix (if possible). If you want a list, you can use `lapply(1:8, function(i) as.vector(T.array[,,i]))` — jogo, Sep 11 '20 at 12:43
or eventually you can use `matrix()`, e.g. `A <- array(1:12, c(2,3,4)); matrix(A, 2*3, 4)` To reorder the dimensions of an array you can use `aperm()` — jogo, Sep 11 '20 at 12:56
`sapply` did the job perfectly too and is probably the most efficient way. Thanks for that! — climsaver, Sep 11 '20 at 14:30

score 2 · Accepted Answer · answered Sep 11 '20 at 11:54

You can use mget to get multiple vectors in a list and bind them by columns :

dplyr::bind_cols(mget(paste0('T.vec_', 1:8)))
#bind_rows works too.
#dplyr::bind_rows(mget(paste0('T.vec_', 1:2)))

Or in base R :

do.call(cbind.data.frame, mget(paste0('T.vec_', 1:8)))

How to create a data frame from multiple vectors?

1 Answers1