Add parallel option to predict.caretStack using foreach

[zachmayer]

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[terrytangyuan]

Hi Zach, is this issue fixed now? I can probably help you with this. I am thinking sticking with apply for small data set and change to foreach for large data set.

[zachmayer]

I'd be happy to get a pull request!

[terrytangyuan]

Sure, but it looks like there are bugs in caretEnsemble? I ran the example code from predict.caretEnsemble both on iris data set and my own data set. Could you check? The error is as follows:

Error in setkeyv(value, key) : 
  4 arguments passed to .Internal(nchar) which requires 3

[terrytangyuan]

Actually, I cleaned my environment and there's no more bug. Sorry. I'll work on this.

[zachmayer]

try using devtools::load_all() instead.

[zachmayer]

Then do devtools::test() and devtools::check() when you're done writing code.