[R] use of names() within lapply()

[Duncan Murdoch]

On 17/04/2013 11:33 AM, Ivan Alves wrote:
> Dear Duncan and A.K.
> Many thanks for your super quick help. The modified lapply did the trick, mapply died with a error "Error in dots[[2L]][[1L]] : object of type 'builtin' is not subsettable".

That's due to a typo:  I should have said

mapply(plot, g, main=names(g))


Duncan Murdoch
> Kind regards,
> Ivan
> On 17 Apr 2013, at 17:12, Duncan Murdoch <murdoch.duncan at gmail.com> wrote:
>
> > On 17/04/2013 11:04 AM, Ivan Alves wrote:
> >> Dear all,
> >>
> >> List g has 2 elements
> >>
> >> > names(g)
> >> [1] "2009-10-07" "2012-02-29"
> >>
> >> and the list plot
> >>
> >> lapply(g, plot, main=names(g))
> >>
> >> results in equal plot titles with both list names, whereas distinct titles names(g[1]) and names(g[2]) are sought. Clearly, lapply is passing 'g' in stead of consecutively passing g[1] and then g[2] to process the additional 'main'  argument to plot.  help(lapply) is mute as to what to element-wise pass parameters.  Any suggestion would be appreciated.
> >
> > I think you want mapply rather than lapply, or you could do lapply on a vector of indices.  For example,
> >
> > mapply(plot, g, main=names)
> >
> > or
> >
> > lapply(1:2, function(i) plot(g[[i]], main=names(g)[i]))
> >
> > Duncan Murdoch
>