[R] failure with merge

[Max Kuhn]

I am merging two data frames:

tuneAcc <- structure(list(select = c(FALSE, TRUE), method =
structure(c(1L, 1L), .Label = "GCV.Cp", class = "factor"), RMSE =
c(29.2102056093962, 28.9743318817886), Rsquared =
c(0.0322612161559773, 0.0281713457306074), RMSESD = c(0.981573768028697,
0.791307778398384), RsquaredSD = c(0.0388188469162352,
0.0322578925071113)),
.Names = c("select", "method", "RMSE", "Rsquared", "RMSESD",
"RsquaredSD"),
class = "data.frame", row.names = 1:2)

finalTune <- structure(list(select = TRUE, method = structure(1L,
.Label = "GCV.Cp", class = "factor"), Selected = "*"), .Names =
c("select", "method", "Selected"), row.names = 2L, class = "data.frame")

using

   merge(x = tuneAcc, y = finalTune, all.x = TRUE)

The error is

  "Error in match.arg(method) : 'arg' must be NULL or a character vector"

This is R version 3.3.1 (2016-06-21), Platform: x86_64-apple-darwin13.4.0
(64-bit), Running under: OS X 10.11.5 (El Capitan).

<some digging>

These do not stop execution:

  merge(x = tuneAcc, y = finalTune)
  merge(x = tuneAcc, y = finalTune, all.x = TRUE, sort = FALSE)

The latter produces (what I consider to be) incorrect results.

Walking through the code, the original call with just `all.x = TRUE` fails
when sorting at the line:

  res <- res[if (all.x || all.y)
    do.call("order", x[, seq_len(l.b), drop = FALSE]) else
     sort.list(bx[m$xi]), , drop = FALSE]

Specifically, on the `do.call` bit. For these data:

  Browse[3]> x
  select method RMSE Rsquared RMSESD RsquaredSD
  2 TRUE GCV.Cp 28.97433 0.02817135 0.7913078 0.03225789
  1 FALSE GCV.Cp 29.21021 0.03226122 0.9815738 0.03881885


  Browse[3]> x[, seq_len(l.b), drop = FALSE]
  select method
  2 TRUE GCV.Cp
  1 FALSE GCV.Cp

and this line executes:

  Browse[3]> order(x[, seq_len(l.b), drop = FALSE])
  [1] 1 2 3 4

although nrow(x) = 2 so this is an issue.

Calling it this way stops execution:

Browse[3]> do.call("order", x[, seq_len(l.b), drop = FALSE])
Error in match.arg(method) : 'arg' must be NULL or a character vector

Thanks,

Max