kable function: "id" in the columns - r

Question

When I trying print table with knitr::kable function "id" word apperas in the column names. How can I change it?
Example:
> x <- structure(c(42.3076923076923, 53.8461538461538, 96.1538461538462,
2.56410256410256, 1.28205128205128, 3.84615384615385,
44.8717948717949, 55.1282051282051, 100),
.Dim = c(3L, 3L),
.Dimnames = structure(list(Condition1 = c("Yes", "No", "Sum"),
Condition2 = c("Yes", "No", "Sum")),
.Names = c("Condition1", "Condition2")), class = c("table", "matrix"))
> print(x)
Condition2
Condition1 Yes No Sum
Yes 42,31 2,56 44,87
No 53,85 1,28 55,13
Sum 96,15 3,85 100,00
> library(knitr)
> kable(x)
|id | Yes| No| Sum|
|:----|-----:|-----:|------:|
|Yes | 42,3| 2,56| 44,9|
|No | 53,8| 1,28| 55,1|
|Sum | 96,2| 3,85| 100,0|
Edit: I find reason of this behavior in the knitr:::kable_mark function. But now I not understand how to make it more flexible.

Answer 1

An alternative to kable might be the general S3 method of pander:
> library(pander)
> pander(x, style = 'rmarkdown')
| | Yes | No | Sum |
|:---------:|:-----:|:-----:|:-----:|
| **Yes** | 42.31 | 2.564 | 44.87 |
| **No** | 53.85 | 1.282 | 55.13 |
| **Sum** | 96.15 | 3.846 | 100 |
If you need to set the decimal mark to comma, then set the relevant option before and use that in your R session:
> panderOptions('decimal.mark', ',')
> pander(x, style = 'rmarkdown')
| | Yes | No | Sum |
|:---------:|:-----:|:-----:|:-----:|
| **Yes** | 42,31 | 2,564 | 44,87 |
| **No** | 53,85 | 1,282 | 55,13 |
| **Sum** | 96,15 | 3,846 | 100 |
There are also some other possible tweaks: http://rapporter.github.io/pander/#pander-options

Answer 2

I think the easiest way is to rip out and replace kable_mark completely. Note: this is quite dirty – but it seems to work, and there is no current way to customise how kable_mark works (you could submit a patch to knitr though).
km <- edit(knitr:::kable_mark)
# Now edit the code and remove lines 7 and 8.
unlockBinding('kable_mark', environment(knitr:::kable_mark))
assign('kable_mark', km, envir=environment(knitr:::kable_mark))
Explanation: First we edit the function and store the amended definition in a temporary variable. We remove the two lines
if (grepl("^\\s*$", cn[1L]))
cn[1L] = "id"
… of course you can also hard-code the amended function rather than editing it, or change the function around completely.
Next we use unlockBinding to make knitr:::kable_mark overridable. If we don’t do this, the next assign command wouldn’t work.
Finally, we assign the patched function back to knitr:::kable_mark. Done.