Transpose xtable while formatting number of digits

Question

I have a dataframe with 2 rows (pre/post treatment) and 11 columns that I want to display as an 11x2 table. The following does the job nicely:

print(xtable(t(df)))

However, I can't figure out how to control the number of digits and also accomplish the transpose. Is a post-xtable transpose possible?

df <- xtable(df)
digits(df) <- c(0,0,0,1,0,1,2,0,1,0,0,2)
t(df) # Does not work; is a post-xtable transpose possible?

I've also tried transposing before creating the xtable, then changing digits for the rows individually, but couldn't get that to work either, i.e.,

df <-xtable(t(df)) # works as intended
digits(df[10,]) <- c(0,1,1) # no error, but does nothing

The general challenge is that in the final table I need a different number of decimals across rows in the same column. This makes me think that some version of the first approach is likely required so that the standard xtable digits controls can be used (i.e., Control number of decimal places on xtable output in R)

In cases like this, I convert everything to character vectors, row by row, where I can control for the number of digits. — Roman Luštrik, Feb 08 '14 at 18:52
I would edit the presentation of the numbers and transpose BEFORE coercing to xtable. Try using `round` — Brandon Bertelsen, Feb 08 '14 at 19:01
@BrandonBertelsen is there a way to do this all in one step like there is with `digits()`? — Bryan, Feb 08 '14 at 19:38

IRTFM · Accepted Answer · 2014-02-08T20:03:18.553

One problem is that your 'digits' argument is 12 items long. Taking off the leading "0" allows warnings to be reduced:

 df <- as.data.frame(matrix(rnorm(22), nrow=2))
 print(xtable(t( mapply("format", df, digits=c(0,0,1,0,1,2,0,1,0,0,2)))))

% latex table generated in R 3.0.2 by xtable 1.7-1 package
% Sat Feb  8 11:37:06 2014
\begin{table}[ht]
\centering
\begin{tabular}{rll}
  \hline
 & 1 & 2 \\ 
  \hline
V1 & 0 & 0 \\ 
  V2 & 0 & 1 \\ 
  V3 &  2.1 & -0.5 \\ 
  V4 & -2 &  1 \\ 
  V5 & -0.7 & -0.7 \\ 
  V6 &  1.03 & -0.28 \\ 
  V7 & -1 &  0 \\ 
  V8 & -0.139 &  0.006 \\ 
  V9 &  0 & -0 \\ 
  V10 &  1 & -0 \\ 
  V11 & 0.33 & 1.10 \\ 
   \hline
\end{tabular}
\end{table}

The transpose functions for matrices and data.frames seem to enforce column uniformity of digit width (or perhaps it is their print methods?

Here's a really kludgy effort:

 capture.output(apply(cbind(t(df), digits), 1, function(x) 
                                            cat( c(round( x[1:2], x[3]) ,"\n") ) )  )
 [1] "0 0 "        "0 1 "        "2.1 -0.5 "   "-2 1 "       "-0.7 -0.7 " 
 [6] "1.03 -0.28 " "-1 0 "       "-0.1 0 "     "0 0 "        "1 0 "       
[11] "0.33 1.1 "   "NULL"

Thanks, this does the trick. Interestingly though, the `digits` argument appears to function differently in your example than it does for xtable: for "format" it equals the total # of desired digits, whereas for xtable it equals the desired number of digits to the right of the decimal point. — Bryan, Feb 08 '14 at 21:10
I think it's giving a minimum number of significant digits on a row-basis. — IRTFM, Feb 08 '14 at 21:44

Transpose xtable while formatting number of digits

1 Answers1