Interactive scatterplots with scatterD3

Basic scatterplot

Starting with the sample mtcars dataset, we can produce a basic scatterplot with the following command :

library(scatterD3)
scatterD3(x = mtcars$wt, y = mtcars$mpg)

This will display a simple visualization with the given variables as x and y axis. There are several interactive features directly available :

• you can zoom in and out with the mouse wheel while the mouse cursor is on the plot
• you can pan the plot by dragging with your mouse
• by hovering over a point, you can display a small tooltip window giving the x and y values

You can customize the points size with the point_size parameter, their opacity with point_opacity, and you can force the plot to have a 1:1 fixed aspect ratio with fixed = TRUE.

scatterD3(x = mtcars$wt, y = mtcars$mpg, point_size = 15, point_opacity = 0.5, fixed = TRUE)

Point labels

You can add text labels to the points by passing a character vector to the lab parameter. Labels size are controlled by the labels_size parameter.

scatterD3(x = mtcars$wt, y = mtcars$mpg, lab = rownames(mtcars), labels_size = 9)

Note that text labels are fully movable : click and drag a label with your mouse to place it where you want. Custom positions are preserved while zooming/panning.

Mapping colors, symbols and size to variables

By passing vectors to the col_var and/or symbol_var arguments, you can map points colors and symbols to other variables.

scatterD3(x = mtcars$wt, y = mtcars$mpg, col_var = mtcars$cyl, symbol_var = mtcars$gear)

A legend is then automatically added. You can manually specify its width with the legend_width argument. Use legend_width = 0 to disable it entirely.

Note that when hovering over a legend item with your mouse, the corresponding points are highlighted. Also note that the mapped variables values are automatically added to the default tooltips.

You can also map symbol sizes with a variable with the size_var argument. size_range allows to customize the sizes range :

scatterD3(x = mtcars$wt, y = mtcars$mpg, col_var = mtcars$cyl, size_var = mtcars$hp, 
          size_range = c(10,1000), point_opacity = 0.7)

Axis limits

You can manually specify the x or y axis limits with the xlim and ylim arguments :

scatterD3(x = mtcars$wt, y = mtcars$mpg, xlim=c(0,10), ylim=c(10,35))

Custom axis and legend labels

You can customize the axis and legend labels with xlab, ylab, col_lab, symbol_lab and size_lab :

scatterD3(x = mtcars$wt, y = mtcars$mpg, col_var = mtcars$cyl, symbol_var = mtcars$gear,
          xlab = "Weight", ylab = "Mpg", col_lab = "Cylinders", symbol_lab = "Gears")

Note that default tooltips are updated accordingly.

Custom tooltips

If the default tooltips don’t suit your needs, you can customize them by providing a character vector to the tooltip_text argument. This can contain HTML tags for formatting.

tooltips <- paste("This is an incredible <strong>", rownames(mtcars),"</strong><br />with ", 
                  mtcars$cyl, "cylinders !")
scatterD3(x = mtcars$wt, y = mtcars$mpg, tooltip_text = tooltips)

You can also disable tooltips entirely with tooltips = FALSE.

Confidence ellipses

You can draw a confidence ellipse around the points :

scatterD3(x = mtcars$wt, y = mtcars$mpg, ellipses = TRUE)

Or around the different groups of points defined by col_var :

scatterD3(x = mtcars$wt, y = mtcars$mpg, col_var = mtcars$cyl, ellipses = TRUE)

Ellipses are computed by the ellipse.default() function of the ellipse package. The confidence level can be changed with the ellipse_level argument (0.95 by default).

Lasso selection tool

Thanks to the d3-lasso-plugin integration made by @timelyportfolio, you can select and highlight points with a lasso selection tool. To activate it, just add a lasso = TRUE argument. The tool is used by shift-clicking and dragging on the plot area (if it doesn’t activate, click on the chart first to give it focus).

scatterD3(x = mtcars$wt, y = mtcars$mpg, lab = rownames(mtcars), lasso = TRUE)

To undo the selection, just shift-click again.

You can specify a custom JavaScript callback function to be called by passing it to the lasso_callback argument as a character string. This function should accept a sel argument, which is a d3 selection of selected points.

Here is an example which shows an alert with selected point labels :

scatterD3(x = mtcars$wt, y = mtcars$mpg, lab = rownames(mtcars), 
          lasso = TRUE,
          lasso_callback = "function(sel) {alert(sel.data().map(function(d) {return d.lab}).join('\\n'));}")

Other options

Finally, and for more specific use cases, you can represent some points as an arrow starting from the origin by using the type_var argument, and you can add a unit circle with unit_circle = TRUE.

scatterD3(x = c(1, 0.9, 0.7, 0.2, -0.4, -0.5), xlab = "x",
          y = c(1, 0.1, -0.5, 0.5, -0.6, 0.7), ylab = "y",
          lab = LETTERS[1:6], type_var = c("point", rep("arrow", 5)),
          unit_circle = TRUE, fixed = TRUE, xlim = c(-1.2, 1.2))

Shiny integration