On Tue, Feb 14, 2012 at 2:31 PM, William Dunlap <wdun...@tibco.com> wrote:
> If you must repeatedly append rows to a data.frame,
> try making the dataset you are filling in a bunch
> of independent vectors, perhaps in a new environment
> to keep things organized.
One complication is I don't know the names of the columns I'm assigning to
before I read them off the file. And crazily, if I change this:
data$x[i] <- i + 0.1
where data is an environment and x a primitive vector, to use a computed
name instead:
data[[colname]][i] <- i + 0.1
Then I get back to way-superlinear performance. Eventually I found I could
work around it like:
eval(substitute(var[ix] <- data,
list(var=as.name(colname), ix=i, data = i+0.1)),
envir = data)
but... as workarounds go that seems to be on the crazy nuts end of the
scale. Why does [[]] impose a performance penalty?
Peter
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