Failing to merge html files in R - html

Question

So I have two html pages, html_1.html and html_2.html I I would like to stack them one on top of the other in R. How to do that?
example:
library(dygraphs)
m1 = dygraph(nhtemp, main = "New Haven Temperatures") %>%
dyRangeSelector(dateWindow = c("1920-01-01", "1960-01-01"))
m2 = dygraph(nhtemp, main = "New Haven Temperatures") %>%
dyRangeSelector(dateWindow = c("1920-01-01", "1960-01-01"))
library(htmltools)
save_html(m1, file = 'm1.html')
save_html(m2, file = 'm2.html')
##Now load and merge m1.html and m2.html

Answer 1

The simplest way is to use an R markdown document:
---
title: ""
output: html_document
---
```{r echo=FALSE, message=FALSE, warning=FALSE}
library(dygraphs)
dygraph(nhtemp, main = "New Haven Temperatures", elementId = "a") %>%
dyRangeSelector(dateWindow = c("1920-01-01", "1960-01-01"))
dygraph(nhtemp, main = "New Haven Temperatures", elementId = "b") %>%
dyRangeSelector(dateWindow = c("1920-01-01", "1960-01-01"))
```
That takes care of many complex things for you.
The heavyweight way is to build the page on your own without getting into the gnarly details of widget javascript dependencies:
library(dygraphs)
library(htmlwidgets)
library(htmltools)
w1 <- dygraph(nhtemp, main = "New Haven Temperatures", elementId = "a") %>%
dyRangeSelector(dateWindow = c("1920-01-01", "1960-01-01"))
w2 <- dygraph(nhtemp, main = "New Haven Temperatures", elementId = "b") %>%
dyRangeSelector(dateWindow = c("1920-01-01", "1960-01-01"))
saveWidget(w1, "w1.html")
saveWidget(w2, "w2.html")
w1_src <- sprintf("data:text/html;base64,%s", openssl::base64_encode(rawToChar(readBin("w1.html", "raw", file.size("w1.html")))))
w2_src <- sprintf("data:text/html;base64,%s", openssl::base64_encode(rawToChar(readBin("w2.html", "raw", file.size("w2.html")))))
tags$html(
tags$body(
tags$iframe(src=w1_src, seamless="", frameborder="0", allowtransparency="true", scrolling="no", style="width:100%;height:400px"),
tags$iframe(src=w2_src, seamless="", frameborder="0", allowtransparency="true", scrolling="no", style="width:100%;height:400px")
)
) %>%
save_html("bothwidgets.html")
You can't just save_html() a widget since they depend on components that get automagically incorporated for you. You need to use iframes in the second approach unless you want to deal with widget dependency de-duplication and proper component inclusion for a lighter weight document on your own.
In this case, the difference isn't too bad, but still substantial. The first output file is 1.3MB the second is 2MB.
Note that you'll likely need to size the iframes better than I did in a production environment.