Using pre-generated character strings with index method for kableExtra group_rows

Question

Using Rmarkdown to generate a PDF. I'm bringing in lengthy text strings generated from a prior function to use as grouped row labels in a table. The normal kableExtra::group_rows method works fine. Since I have the same number of rows in each group, I'd like to use the index method, but that doesn't seem to work:

---
output: 
  pdf_document:
    latex_engine: xelatex
    fig_caption: true
---
```{r}
library(magrittr)
library(knitr)
library(kableExtra)

# Build some data
df <- data.frame(x=1:12, y=13:24, z=25:36)

# Row grouping text gets generated from a separate function
gtext <- c("Group 1: text that I don't want to write out",
           "Group 2: because it gets generated from something else",
           "Group 3: so let's make life easy")

# This works fine:
df %>%
  kable(format="latex", booktabs = TRUE, row.names=FALSE) %>%
  group_rows(gtext[1],1,4) %>%
  group_rows(gtext[2],5,8) %>%
  group_rows(gtext[3],9,12)

# But this doesn't:
df %>%
  kable(format="latex", booktabs = TRUE, row.names=FALSE) %>%
  group_rows(index=c(gtext[1]=4,
                     gtext[2]=4,
                     gtext[3]=4))
```

I get the following error upon knitting: "Error in parse(text = x, srcfile = src) : :23:30: unexpected '=' 22:"

Over the course of 40+ tables with some that have up to 10 row groupings, it's easy to see how the index method would save time and prevent errors. Added functionality here (or a workaround that I may have missed) would be most excellent!

I can get this doc to render to html with `group_rows(index=setNames(c(4, 4, 4), gtext))`. Perhaps that might help? — markdly, Oct 26 '17 at 17:31
@markdly's answer should work. After all, it's nothing but a named vector. ;) — Hao, Oct 26 '17 at 18:21
@markdly, yep that worked for PDF as well. If you'd like to enter that as an answer I'll accept & upvote. Saves a ton of writing! — bcarothers, Oct 26 '17 at 21:04

score 2 · Accepted Answer · answered Oct 26 '17 at 21:17

I could render this document to html by using

group_rows(index=setNames(c(4, 4, 4), gtext))

The issue appears to be the way you are attempting to create the named vector for the index argument. If you try this in the console, you'll get an error:

c(gtext[1] = 4, gtext[2] = 4, gtext[3] = 4)

While this does not:

setNames(c(4, 4, 4), gtext)
#>           Group 1: text that I don't want to write out 
#>                                                      4 
#> Group 2: because it gets generated from something else 
#>                                                      4 
#>                       Group 3: so let's make life easy 
#>                                                      4

Using pre-generated character strings with index method for kableExtra group_rows

1 Answers1