omit cell entries in xtable markdown

Question

I would like to report descriptive values in a table (I am sure they should be in a table and not in a figure). The data comes from a 3-factorial experiment, so the table that I am able to produce with xtable (I'm doing it in an Rmarkdown and Knitr and have never used LaTex) contains one line per data value along the format:

group | condition | type | value

When all the lines are printed below each other, this in not very readable, for example the "group" entry remains the same for 10 lines. Is there a possibility to just print it the first time (in the first line) and then omit it until the "group" changes to the next group (only print it in line 11)? My table should have apa-format, so I use either rapa::apa(mytable) or papaja::apa_table(mytable) for the final print. Any help would be appreciated, thanks!

Kristofersen Kristofersen · Accepted Answer · 2017-02-17T18:29:55

There are a few different ways to do this.

library(data.table)

dt = data.table("Group" = c(rep("A",4),rep("B",4)), "value" = rep(1:4, each = 2))
knitr::kable(dt)

> dt
   Group value
1:     A     1
2:     A     1
3:     A     2
4:     A     2
5:     B     3
6:     B     3
7:     B     4
8:     B     4

We can remove duplicates across all rows

knitr::kable(dt[!duplicated(dt),])

|Group | value|
|:-----|-----:|
|A     |     1|
|A     |     2|
|B     |     3|
|B     |     4|

Or, we can remove duplicates according to specific rows

knitr::kable(unique(dt,by = c("Group")))
|Group | value|
|:-----|-----:|
|A     |     1|
|B     |     3|

Then, since that can match to multiple options we can specify which one we want to grab

knitr::kable(dt[unique(dt,by = c("Group")),.(Group, value), mult = "first"])
|Group | value|
|:-----|-----:|
|A     |     1|
|B     |     3|

knitr::kable(dt[unique(dt,by = c("Group")),.(Group, value), mult = "last"])
|Group | value|
|:-----|-----:|
|A     |     2|
|B     |     4|

EDIT

To not print values in a specific group that have been duplicated

dt$Group = ifelse(duplicated(dt$Group),"",dt$Group)
knitr::kable(dt)
|Group | value|
|:-----|-----:|
|A     |     1|
|      |     1|
|      |     2|
|      |     2|
|B     |     3|
|      |     3|
|      |     4|
|      |     4|

omit cell entries in xtable markdown

3 Answers