## R

### ggforce

Annotation is important for storytelling, and ggforce provides a family of geoms that makes it easy to draw attention to, and describe, features of the plot. They all work in the same way, but differ in the way they enclose the area you want to draw attention to.

### directlabels

An extensible framework for automatically placing direct labels onto multicolor ‘lattice’ or ‘ggplot2’ plots. Label positions are described using Positioning Methods which can be re-used across several different plots. There are heuristics for examining “trellis” and “ggplot” objects and inferring an appropriate Positioning Method.

### ggwordcloud

ggwordcloud provides a word cloud text geom for ggplot2. The placement algorithm implemented in C++ is an hybrid between the one of wordcloud and the one of wordcloud2.js. The cloud can grow according to a shape and stay within a mask. The size aesthetic is used either to control the font size or the printed area of the words. ggwordcloud also supports arbitrary text rotation. The faceting scheme of ggplot2 can also be used.

The `ggwordcloud`

package implements a spiraling algorithm
to prevent text labels from overlapping each other.

### wordcloud

Pretty word clouds.

The `wordcloud`

package implements a spiraling algorithm
to prevent text labels from overlapping each other.

### FField

Force field simulation of interaction of set of points. Very useful for placing text labels on graphs, such as scatterplots.

I found that functions in the `FField`

package were not
ideal for repelling overlapping rectangles, so I wrote my own.

See this
gist for examples of how to use the `wordcloud`

and
`FField`

packages with `ggplot2`

.

## Javascript

### vega-label

**Fast and Flexible Overlap Detection for Chart Labeling with
Occupancy Bitmaps**

Chanwut Kittivorawang, Dominik Moritz, Kanit Wongsuphasawat, Jeffrey Heer

### D3-Labeler

A D3 plug-in for automatic label placement using simulated annealing

Evan Wang’s plugin that extends D3 v3. He also described the approach in his paper.

### d3fc-label-layout

A D3 layout that places labels avoiding overlaps, with strategies including simulated annealing, greedy and a strategy that removes overlapping labels.

Colin Eberhardt’s implementation for D3 v4.

### d3-voronoi-labels

A Voronoi tessellation can assist in labeling scatterplots. The area of the Voronoi cell associated with each point determines whether the point is labeled: points with larger cells tend to have room to accommodate labels.

## Python

### adjustText

A small library for automatically adjusting text position in matplotlib plots to minimize overlaps.

Ilya Flyamer’s Python library that extends matplotlib.

## Academic Papers

### An Efficient Algorithm for Scatter Chart Labeling

Sebastian Theophil, Arno Schödl

This paper presents an efficient algorithm for a new variation of the point feature labeling problem. The goal is to position the largest number of point labels such that they do not intersect each other or their points. First we present an algorithm using a greedy algorithm with limited lookahead. We then present an algorithm that iteratively regroups labels, calling the first algorithm on each group, thereby identifying a close to optimal labeling order. The presented algorithm is being used in a commercial product to label charts, and our evaluation shows that it produces results far superior to those of other labeling algorithms.

This might be a good start for a revision of ggrepel.

### Chapter 15. Labeling Algorithms

Konstantinos G. Kakoulis, Ioannis G. Tollis

An important aspect of information visualization is the automatic placement of text or symbol labels corresponding to graphical features of drawings and maps. Labels are textual descriptions that convey information or clarify the meaning of complex structures presented in a graphical form. The automatic label placement problem is identified as an important research area by the ACM Computational Geometry Task Force [C +99]. It has applications in many areas including cartography [RMM+95], geographic information systems [Fre91], and graph drawing [DETT99].

Handbook of Graph Drawing and Visualization, Roberto Tamassia (Editor), CRC Press, June 24, 2013.