Column alignment in xtable output

Question

I'm using xtable to manage R output in Sweave. See code below:

CC <- data.frame(
    y = c(449, 413, 326, 409, 358, 291, 341, 278, 312)/12,
    P = ordered(gl(3, 3)), N = ordered(gl(3, 1, 9))
)
CC.aov <- aov(y ~ N * P, data = CC , weights = rep(12, 9))
Summary <- summary(CC.aov, split = list(N = list(L = 1, Q = 2),
                                        P = list(L = 1, Q = 2)))
Summary

            Df Sum Sq Mean Sq
N            2 1016.7   508.3
  N: L       1 1012.5  1012.5
  N: Q       1    4.2     4.2
P            2  917.4   458.7
  P: L       1  917.3   917.3
  P: Q       1    0.0     0.0
N:P          4  399.3    99.8
  N:P: L.L   1  184.1   184.1
  N:P: Q.L   1  152.1   152.1
  N:P: L.Q   1   49.0    49.0
  N:P: Q.Q   1   14.1    14.1

I like to indent the first column as shown in the output above. But when I use xtable(Summary) the first column is aligned left. I know how to align left, right or center but could not figure out how to get the output as indented in the first.

Answer 1

This example shows how to customize the table combining the use of the sanitize argument in xtable and the function \hskip in latex.

The code would be:

named = rownames(Summary[[1]])
tags= gsub("  "," ",named)
rownames(Summary[[1]])= c(ifelse(nchar(tags)<8,tags,paste("\\hskip .5cm",tags,sep=' ')))
print(xtable(Summary[[1]]), type="latex", sanitize.text.function = function(x){x})

EDIT: Following Dwin's suggestion of using

grepl("^ ", rownames(Summary[[1]])

That provides a more general solution. The code would change to:

named = rownames(Summary[[1]])
tags= grepl("^ ", rownames(Summary[[1]]))
rownames(Summary[[1]])= c(ifelse(tags==F,named,paste("\\hskip .5cm",named,sep=' ')))
print(xtable(Summary[[1]]), type="latex", sanitize.text.function = function(x){x})