Interactive Visualization in R with apexcharter

August 3, 2019

(This article was first published on r-bloggers on Programming with R, and kindly contributed to R-bloggers)

Interactive Visualizations are powerful these days because those are all made for web. Web – simply a combination of html,css and javascript which build interactive visualizations. Thus, paving way for a lot of javascript charting libraries like highcharts.js, apexcharts.js.

Thanks to htmlwidgets of R, many R developers have started porting those javascript charting libraries to R and dreamRs is one of such leading Developer groups working on the intersection R + Web. In this post, We’ll learn how to use the R package apexcharter which is developed by dreamRs – Victor Perrier and Team to make beautiful interactive visualizations that are based on apexcharts.js

apexcharter – Intro, Installation & Loading

apexchart.js is a modern JavaScript charting library to build interactive charts and visualizations with simple API. apexcharter is built as a htmlwidget (R Package) for apexchart.js and the API design is inspired by highcharter. apexcharter requires RStudio >= 1.2 to properly display charts.

Install the stable version from CRAN with:


Or install the development version from GitHub with:

# install.packages("devtools")

Once successfully installed, apexcharter can be loaded using


Simple Example

The main function of apexcharter is the apex() function whose first argument is data. Thus, enabling the support of pipe %>% operator. The second argument is mapping – aesthetics (x & y) and the third one is type of the chart – which takes multiple values like scatter, bar, line and much more.

Let’s take R’s in-built mtcars dataset and draw a simple bar chart.


mtcars %>% 
  count(cyl) %>% 
  apex(type = "bar",
       mapping = aes(x = "cyl", y = n))

Now, that’s a beautiful interctive chart. Let’s go ahead and see a few more examples of something bigger than a simple bar chart.

Building Interactive Heatmap / Correlation Plot

Let’s try to visualize a Heatmap (of Correlation Plot) of numeric columns of mtcars dataset. To do that, we’ve to first select the numeric columns which we’ll do with select_if(is.numeric) and then we’ve to build the correlation matrix which the base-R function cor() does it smoothly.

Now that we’ve got a matrix let’s convert it to a data.frame and for us to draw a heatmap – we need 3 things primarily:

  • x-axis – categorical
  • y-axis – categorical
  • fill value – continuous

So, we’ll convert the rownames of the resultant dataframe to a column and then convert the wide format data into long format using pivot_longer().

At this point our data is in the desirable format for a heatmap. Simply for aesthetics improvement, let’s round off the correlation values.

Finally, we’ll use our apex() function with type = 'heatmap' that gives us a color-filled heatmap (that’s also interactive).


mtcars %>% 
  select_if(is.numeric) %>% 
  cor() %>% %>% 
  rownames_to_column("col") %>% 
  pivot_longer(cols = -col, names_to = "type") %>% 
  mutate(value = round(value,2)) %>% 
  apex(type = "heatmap",
       mapping = aes(x = col, y = type, fill = value)) 

Building Interactive Time-Series (Line) Graph

If there’s a plot where Interactive Charts are incredibly valuable, I think it’s Time-Series Graph where labelling on traditional (static) chart would sometimes make the chart clunky and less readable.

Let’s build an Interactive Time-series plot with the apexcharter library. As you can see below, all it takes is a dataframe with a column denoting the time field and another column with the actual value for that time.


df <- data.frame(Y=as.matrix(EuStockMarkets), date=time(EuStockMarkets))

df %>% 
  apex(type = "line",
       mapping = aes(x = date, y = Y.DAX)) 


Thus, We learnt how to build interactive charts using apexcharter that follows a very minimal API similar to highcharter.

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