How to add horizontal scroll bar for a ggplot plot in RMarkdown html

Question

I have recently started using RMarkdown for reporting purposes. A specific report I am working on contains tables and plots for data acquired from many experiments carried out over the years - sort of updating and summarising data quickly.

While I have found a way to add scrollbars/scroll boxes for tables (by using Kable) and code chunk outputs, I have not been able to add scrollbars for plots. Most of plots are not big and its not an issue, but for one/two plots there are many categories and I need the plot to not resize when browser window size is changed or make the width of the entire page huge. Ideally, if possible, it should be of a specific size and in a scrollbox of fixed width.

Here is an example of the kind of plot I am trying to do. Any suggestions are welcome!

---
title: "Add horizontal scrol"
author: "KTy"
date: "9/21/2018"
output: html_document
---

```{r setup, include=FALSE}
knitr::opts_chunk$set(echo = TRUE)
require(ggplot2)
```

## R Markdown
### Want to add horizontal scroll bar around a plot

```{r rnorm_box_violin}
set.seed(2300)
xdf1 <- data.frame(  var1 = rnorm(  10000 , mean = 5000 , sd = 10) , str1 = rep("a0",10000)  )

for ( x in 10:50 ){
  n <- sample(x = c(10,0.1) , size = 1)
  xdf2 <- data.frame( var1 = rnorm(  x*n*1000 , mean = 5000+(x/2) , sd = 10) , str1 = rep(paste0("a",x),x*n*1000))
  xdf1 <- rbind(xdf1,xdf2)
  }

plot1 <- ggplot(  data = xdf1  , aes( x = str1 , y = var1  ))  + 
  geom_violin(fill='grey90', scale = 'count', colour = 'grey70') + 
   geom_boxplot( width = 0.2 ,  alpha = 0.1 , colour = 'grey30')+
  theme_bw()+
  theme(axis.text.x =  element_text(angle = 45, hjust = 1 ,vjust = 1))
```
Produces this plot:
```{r plot_it , echo = FALSE, width = 20 , height = 7}
plot1
```

I am using RStudio on Mac. I hope what I am asking makes sense, please leave comments if anythings is not clear and I can try to explain further. Cheers, Thank you!

Answer 1

You can add custom CSS to your knitr document:

    ...
    plot1 <- ggplot(  data = xdf1  , aes( x = str1 , y = var1  ))  + 
    geom_violin(fill='grey90', scale = 'count', colour = 'grey70') + 
    geom_boxplot( width = 1 ,  alpha = 0.1 , colour = 'grey30')+
    theme_bw()+
    theme(axis.text.x =  element_text(angle = 45, hjust = 1 ,vjust = 1))
```
<style>
  .superbigimage{
      overflow-x:scroll;
      white-space: nowrap;
  }

  .superbigimage img{
     max-width: none;
  }


</style>


This produces the plot with a special css class
<div class="superbigimage">
```{r plot_it , echo = FALSE, fig.width=20,fig.height=3}
plot1
```
</div>


This produces the plot with the default settings
```{r plot_it2 , echo = FALSE, fig.width=20,fig.height=3}
plot1
```

Image for the lazy: