Leaflet Not Rendering in Dynamically Generated R Markdown HTML Knitr

Leaflet not rendering in dynamically generated R markdown html knitr

This is a similar problem as described here with Highcharter

Try:

---
title: "Test Leaflet Tabs"
output: html_document
---

`r knitr::opts_chunk$set(echo = FALSE, warning = FALSE, message = FALSE, cache = F)`

```{r setup, include=FALSE}
library(leaflet)
leaflet()
```

```{r,results='asis'}

filtered_list <- 1:3
cat("## Tabs {.tabset .tabset-fade .tabset-pills}", "\n")
for (estates in filtered_list){
    cat("###", estates, "\n")
    cat("\n\n\n")
    cat("This is where the map will go ")
    
# generate leaflet plot (doesn't even show white space if not stored in tagList)
    page <- htmltools::tagList(
         leaflet() %>%
            addTiles() %>%  # Add default OpenStreetMap map tiles
            addMarkers(lng=174.768, lat=-36.852, popup="The birthplace of R")
    )
    cat(as.character(page))
    }
```

Recommended way to initialize JS renderer in 'asis' R Markdown chunk

The answer to my question has been given by @cderv :

https://github.com/rstudio/rmarkdown/issues/1877#issuecomment-679864674

The results = 'asis' is now more documented in https://bookdown.org/yihui/rmarkdown-cookbook/results-asis.html#results-asis . It is aimed at generating raw mardown content from a R chunk. Anything must result in a text output, and implicitly that means no knitr magic really happens for any R object in those chunk, because knitr does no adjustment when knit_printing the content (as it is juts text)

I think I would not use result = 'asis' to cat() a complex R object like an htmlwidget. You found a workaround but you may encounter other issues.

As this answer has been liked by @yihui, it gives a hint that cat + asis on htmlwidget should be used at one's own risk.

However, I'll personnaly continue to use the workarounds mentioned in the question, because as long as it works I find it very practical.

Thanks @atusi & @cderv for their valuable input.

Dynamically loop through htmlwidgets and add knitr formatting for RMarkdown

I'll copy my response to the Github issue below.

Good question, and I think others will be helped by this discussion. It might be easiest to start by building something like what you propose from scratch without the aid of rmarkdown.

manually build

# https://github.com/ramnathv/htmlwidgets/pull/110#issuecomment-216562703

library(plotly)
library(htmltools)
library(markdown)
library(shiny)

browsable(
  attachDependencies(
    tagList(
      tags$div(
        class="tabs",
        tags$ul(
          class="nav nav-tabs",
          role="tablist",
          tags$li(
            tags$a(
              "data-toggle"="tab",
              href="#tab-1",
              "Iris"
            )
          ),
          tags$li(
            tags$a(
              "data-toggle"="tab",
              href="#tab-2",
              "Cars"
            )
          )
        ),
        tags$div(
          class="tab-content",
          tags$div(
            class="tab-pane active",
            id="tab-1",
            as.widget(
              plot_ly(
                iris,
                x = iris[["Sepal.Length"]],
                y = iris[["Sepal.Width"]], 
                mode = "markers"
              )
            )
          ),
          tags$div(
            class="tab-pane",
            id="tab-2",
            as.widget(
              plot_ly(
                cars,
                x = speed,
                y = dist, 
                mode = "markers"
              )
            )
          )
        )
      )
    ),
    # attach dependencies
    #  see https://github.com/rstudio/rmarkdown/blob/master/R/html_document.R#L235
    list(
      rmarkdown::html_dependency_jquery(),
      shiny::bootstrapLib()
    )
  )
)

in rmarkdown

There is probably a better way to make this work, but until someone sets me straight, we can take the approach from above and use it in rmarkdown. Unfortunately, this is still very manual. For more reference, here is the code that RStudio uses to build tabsets.

---
title: "tabs and htmlwidgets"
author: "Kent Russell"
date: "May 3, 2016"
output: html_document
---

```{r echo=FALSE, message=FALSE, warning=FALSE}
library(plotly)
library(htmltools)
library(magrittr)

# make a named list of plots for demonstration
#  the names will be the titles for the tabs
plots <- list(
  "iris" = plot_ly(
    iris,
    x = iris[["Sepal.Length"]],
    y = iris[["Sepal.Width"]], 
    mode = "markers"
  ),
  "cars" = plot_ly(
    cars,
    x = speed,
    y = dist, 
    mode = "markers"
  )
)

# create our top-level div for our tabs
tags$div(
  # create the tabs with titles as a ul with li/a
  tags$ul(
    class="nav nav-tabs",
    role="tablist",
    lapply(
      names(plots),
      function(p){
        tags$li(
          tags$a(
            "data-toggle"="tab",
            href=paste0("#tab-",p),
            p
          )
        )
      }
    )
  ),
  # fill the tabs with our plotly plots
  tags$div(
    class="tab-content",
    lapply(
      names(plots),
      function(p){
         tags$div(
          #  make the first tabpane active
          class=ifelse(p==names(plots)[1],"tab-pane active","tab-pane"),
          #  id will need to match the id provided to the a href above
          id=paste0("tab-",p),
          as.widget(plots[[p]])
        )
      }
    )
  )
) %>%
  # attach the necessary dependencies
  #  since we are manually doing what rmarkdown magically does for us
  attachDependencies(
    list(
      rmarkdown::html_dependency_jquery(),
      shiny::bootstrapLib()
    )
  )
```

---

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