Testing methods for df_print-like custom table printing in quarto

tables_demo.qmd

---
title: "Table printing demo"
author: "Lisa DeBruine"
toc: true
toc_float: true
---

## Code

These functions should override `knitr::knit_print()` for data frames, but wasn't working at all until I learned in [the knit_print vignette](https://cran.r-project.org/web/packages/knitr/vignettes/knit_print.html) that you have to use `registerS3method()`.

<style>
caption { color: purple !important; }
</style>


```{r}
# custom knit_print functions for data.frame
library(knitr)

# print everything as paged ----
# knit_print.data.frame <- function (x, options, ...) {
#   rmarkdown::paged_table(x, options) |>
#     rmarkdown:::print.paged_df()
# }
# registerS3method("knit_print", "data.frame", knit_print.data.frame)

# print everything as kable ----
# knit_print.data.frame <- function (x, options, ...) {
#   knitr::kable(x) |> knitr::knit_print(options, ...)
# }
# registerS3method("knit_print", "data.frame", knit_print.data.frame)

# super-customised table printing ----

`%||%` <- function(l, r) {
  if (is.null(l)) r else l
}

knit_print.data.frame <- function (x, options, ...) {
  # get options
  digits <- options$digits %||% getOption("digits")
  rownames <- options$rownames %||% FALSE
  pageLength <- options$pageLength %||% 10 
  escape <- options$escape %||% TRUE
  caption <- options$fig.cap
  
  # remove caption so it doesn't print twice (NOT WORKING)
  options$fig.cap <- NULL 
  
  # use DT for longer tables in html
  if (nrow(x) > pageLength & knitr::is_html_output()) {
    numeric_cols <- sapply(x, is.numeric) |> which() |> names()
    dt <- DT::datatable(x, 
                        rownames = rownames,
                        caption = caption,
                        escape = escape,
                        width = "100%",
                        height = "auto",
                        options = list(pageLength = pageLength),
                        selection = "none")
    if (length(numeric_cols) > 0) {
      dt <- DT::formatRound(dt, 
                            columns = numeric_cols,
                            digits = digits)
    }
    knitr::knit_print(dt, options)
  } else {
    # use kableExtra::kable for PDFs or shorter tables
    k <- kableExtra::kable(x, 
                      digits = digits, 
                      row.names = rownames, 
                      caption = caption,
                      escape = escape) |>
      kableExtra::kable_styling(
        full_width = options$full_width,
        bootstrap_options = c("striped", "hover")
      )
    
    if (knitr::is_html_output()) {
        k <- c("<div class=\"kable-table\">", k, "</div>") |>
          paste(collapse = "\n")
    }
    
    knitr::asis_output(k)
  }
}

registerS3method("knit_print", "data.frame", knit_print.data.frame)
```




## Test

Make data.frame and tbl_df object with 5 and 26 rows.

```{r}
df5 <- data.frame(x = rnorm(5), y = LETTERS[1:5])
df26 <- data.frame(x = rnorm(26), y = LETTERS)
tbl5 <- tibble::tibble(x = rnorm(5), y = LETTERS[1:5])
tbl26 <- tibble::tibble(x = rnorm(26), y = LETTERS)
```

::: {.panel-tabset}
### Data frame - 5 rows

Should be displayed with `kableExtra::kable()`.

```{r}
df5
```


### Data frame - 26 rows

Should be displayed with `DT::datatable()`.

```{r}
df26
```


### Tibble - 5 rows

Should be displayed with `kableExtra::kable()`

```{r}
tbl5
```

### Tibble - 26 rows

Should be displayed with `DT::datatable()`

```{r}
tbl26
```

:::

## Option Tests

Testing options in the r chunk header.

::: {.panel-tabset}

### digits

Set the number of digits to display in numeric columns. Defaults to `getOption("digits")`.

```{r, digits = 3}
# digits = 3
tbl5
```

```{r, digits = 4}
# digits = 4
tbl26
```


### rownames

rownames are FALSE by default

```{r, rownames = TRUE}
# rownames = TRUE
tbl5
```

```{r, rownames = TRUE}
# rownames = TRUE
tbl26
```

### fig.cap

Figure captions are displaying twice (the caption from DT or kable is in purple).

```{r, fig.cap="This is my figure caption for a tibble with 5 rows"}
# fig.cap="This is my figure caption for a tibble with 5 rows"
tbl5
```


```{r, fig.cap="This is my figure caption for a tibble with 26 rows"}
# fig.cap="This is my figure caption for a tibble with 26 rows"
tbl26
```



### pageLength

Set the page length for DT, if the table is <= to that, will display as kable.

```{r, pageLength = 3}
# pageLength = 3, so should be a DT
tbl5
```


```{r, pageLength = 30}
# pageLength = 30, so should be a kable
tbl26
```

### escape

`escape` is TRUE by default. Set to FALSE to use html or latex in tables.

```{r, escape = FALSE}
# escape = FALSE
tibble::tibble(styles = c("<i>italics</i>", "<b>bold</b>"))
```

```{r, escape = FALSE}
# escape = FALSE
tibble::tibble(styles = rep(c("<i>italics</i>", "<b>bold</b>"), 10))
```

### full_width

For kable only, defaults to TRUE for html and FALSE for pdf.

```{r, full_width = TRUE}
# full_width = TRUE
tbl5
```

```{r, full_width = FALSE}
# full_width = FALSE
tbl5
```


:::