treatment of NULL in rbind.fill doesn't match rbind

[ajdamico]

not sure if this is intentional, possible improvement to rbind.fill()

library(plyr)

# works
rbind( NULL , mtcars )

# works
rbind.fill( data.frame() , mtcars )

# breaks
rbind.fill( NULL , mtcars )

[otsaw]

This used to work at least in 1.7.1.

It seems that the fix to issue #51 is at fault.

[hadley]

Do you have a real use case where this causes a problem?

[otsaw]

Yes, I'd say so. Something like

dfs = lapply(...)
df = do.call(rbind.fill, dfs)

Depending on what the function under lapply does and what kinds of data it happens to have it's fully possible to get a NULL value instead of a zero-length data frame. And since at least unlist and rbind gracefully discard NULLs, I'm not used to trying to avoid them.

[hadley]

Makes sense - now fixed :)