On Jan 11, 2012, at 1:40 PM, Chris Conner wrote:
> As a newer R practicioner, it seems I stump myself weekly (at least) with
> issues that have spinning my wheels. Here is yet another... I'm trying to
> turn a list of numeric vectors (of uneual length) inot a dataframe. Each
> vector held in the list represents a row, and there are some rows of unequal
> length. I would like NAs as placeholders for "missing" data in the shorter
> vectors. I think I'm missing something quite basic.
>
> v1 <- c(1,2,3,4)
> v2 <- c(1,2)
> lst1 <- list(v1,v2)
>
> Of course there is the intuitive:
>
> as.data.frame(lst1)
>
> However, the recycling rule (expectedly) reclycles 1,2 versus using NAs as
> placeholders.
>
> Then, looking into Teetor's R Cookbook, there is a piece of code that looked
> (from the description) like it might do the trick:
>
> do.call(rbind, Map(as.data.frame,lst1)
>
> But I get the error:
> Error in match.names(clabs, names(xi)) :
> names do not match previous names
>
> Thinking the source of the error had to do with the vectors of unequal
> lenght, I tried Hadley's rbind.fill thusly:
>
> library(reshape)
> do.call(rbind.fill, Map(as.data.frame,lst1)
>
> Which produced a dataset, but gain, not in the desired format.
>
> Thanks in advance to anyone that can bring my frustrations to end!
> C
> [[alternative HTML version deleted]]
There may be an easier way, but try this:
list2df <- function(x)
{
MAX.LEN <- max(sapply(x, length), na.rm = TRUE)
DF <- data.frame(lapply(x, function(x) c(x, rep(NA, MAX.LEN - length(x)))))
colnames(DF) <- paste("V", seq(ncol(DF)), sep = "")
DF
}
> list2df(lst1)
V1 V2
1 1 1
2 2 2
3 3 NA
4 4 NA
HTH,
Marc Schwartz
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