Plotly plot doesn't render within for loop of RMarkdown document - r

Question

I'm trying to build a report dynamically that requires running a loop, and for each iteration printing some messages, tables, and a plot. I can get everything to work except for the plot.
example.rmd
```{r echo=FALSE, results='asis', fig.keep='all', message = FALSE, warning = FALSE}
library(knitr)
library(plotly)
for(i in 1:4){
foo <- iris[sample(nrow(iris), 20), ]
cat("\n")
cat("# Iteration", i, "\n")
# Print the first few lines
print(kable(head(foo)))
cat("\n")
# Plot Sepal.Width vs Petal.Length using ggplotly()
plt <- ggplot(foo, aes(x = Sepal.Width, y = Petal.Length))+geom_point()
# plot(plt) # <- this works
# plot(ggplotly(plt)) # <- this doesn't work
# ggplotly(plt) # <- this doesn't work
cat("\n")
}
```
How can I get the plotly plots to render in my report?

Answer 1

Following this post on github about basically the same issue, I was able to put together this very hacky solution. Would love to find a better method.
```{r echo=FALSE, results='asis', fig.keep='all', message = FALSE, warning = FALSE}
library(knitr)
library(plotly)
# Build list of outputs
output <- list()
for(i in 1:4){
foo <- iris[sample(nrow(iris), 20), ]
# Header for iteration
txt <- paste0("#Iteration ", i)
output[[length(output) + 1L]] <- txt
# Table of the first few lines
tbl <- kable(head(foo))
output[[length(output) + 1L]] <- tbl
# Plot
plt <- ggplotly(ggplot(foo, aes(x = Sepal.Width, y = Petal.Length))+geom_point())
output[[length(output) + 1L]] <- plt
}
# Render the outputs
for(j in 1:length(output)){
x <- output[[j]]
if(inherits(x, "character")){
cat("\n")
cat(x)
} else if(inherits(x, "knitr_kable")){
cat("\n")
print(x)
}
else {
# print the html piece of the htmlwidgets
cat("\n")
cat(htmltools::renderTags(as.widget(x))$html)
}
}
```
```{r echo=FALSE, messages=FALSE, warning=FALSE}
# Attach the Dependencies since they do not get included with renderTags(...)$html
deps <- lapply(
Filter(f = function(x){inherits(x,"htmlwidget")}, x = output),
function(hw){
htmltools::renderTags(hw)$dependencies
}
)
htmltools::attachDependencies(x = htmltools::tagList(), value = unlist(deps,recursive=FALSE))
```