I'm trying to compute quantiles by factor and print out the resulting aggregate to latex format using xtable. Unfortunately, I'm getting some wonky behavior. And a clean solution would be appreciated.
To create an example:
tm <- data.frame(f=c("a","b","c"),v=runif(30))
tm$f <- factor(tm$f)
agv <- aggregate(v~f,tm, quantile)
The output agv isn't accepted by xtable:
xtable(agv)
gives
Error in cols[, i + pos] <- do.call("formatC", curFormatArgs) : number of items to replace is not a multiple of replacement length
even though print(agv) is
f v.0% v.25% v.50% v.75% v.100%
1 1 0.002970944 0.253247687 0.571891610 0.766606825 0.986142807
2 2 0.002129951 0.328739086 0.558132094 0.799115979 0.991067470
3 3 0.011059184 0.285322522 0.496035672 0.770908599 0.994420787
because apparently dim(agv) is actually [1] 3 2
So I tried:
cbind(featureName=agv$f, agv$v)
which results in the character factors converting to numeric values for some reason.
After some trial and error, this is the solution I settled on:
cbind(f=as.character(agv$f), data.frame(agv$v,check.names=F))
which, gives me the result I want in xtable:
\begin{table}[ht]
\centering
\begin{tabular}{rlrrrrr}
\hline
& f & 0\% & 25\% & 50\% & 75\% & 100\% \\
\hline
1 & a & 0.00 & 0.25 & 0.48 & 0.75 & 0.99 \\
2 & b & 0.00 & 0.28 & 0.46 & 0.74 & 1.00 \\
3 & c & 0.02 & 0.21 & 0.44 & 0.63 & 1.00 \\
\hline
\end{tabular}
\end{table}
Anyway, I'm just curious whether there's a cleaner solution with fewer lines involved.
A slightly more direct approach (though not much different conceptually than what you've already done) might be to use do.call(data.frame, ...). The following works for me.
xtable(do.call(data.frame, c(agv, check.names = FALSE)))
For me, that returns:
> xtable(do.call(data.frame, c(agv, check.names = FALSE)))
% latex table generated in R 3.0.0 by xtable 1.7-1 package
% Thu Apr 25 11:10:26 2013
\begin{table}[ht]
\centering
\begin{tabular}{rlrrrrr}
\hline
& f & v.0\% & v.25\% & v.50\% & v.75\% & v.100\% \\
\hline
1 & a & 0.06 & 0.27 & 0.38 & 0.64 & 0.94 \\
2 & b & 0.20 & 0.38 & 0.52 & 0.70 & 0.87 \\
3 & c & 0.01 & 0.22 & 0.60 & 0.87 & 0.99 \\
\hline
\end{tabular}
\end{table}
xtable also works with data.tables, so you can also do something like the following:
library(data.table)
DT <- data.table(tm, key = "f")
xtable(DT[, as.list(quantile(v)), by = key(DT)])
Here, DT[, as.list(quantile(v)), by = key(DT)] will give you the same results as your "agv" object.