{emphatic} augments the output of data.frames and matrices in R by adding user-defined ANSI highlighting.

See the online documentation for vignettes and more examples.

What’s in the box

There are separate high-level functions for highlighting data.frames and matrices, and a low-level function which can be used on both.

The hl_ prefix can be read as highlight.

• hl() for highlighting data.frames
• hl_matrix() for highlighting matrices
• hl_loc() for low-level control of highlighting of both data.frames and matrices
• hl_opt() to set some local options on the current emphatic object e.g. full_colour option sets 24-bit colour mode.
  
• hl_opt_global() sets global options for highlighting. These values will be the default unless overridden with a call to hl_opt() for the given emphatic object.

Installation

You can install from GitHub with:

# install.package('remotes')
remotes::install_github('coolbutuseless/emphatic')

Warning

• This package calls eval() on user-supplied code and extreme caution should be taken before exposing functions in this package to the internet (e.g. via shiny)

Vignettes

Intro

• Guided Example

Speicifying rows, columns and colours

• Specifying rows
• Specifying columns
• Specifying colours

Test cases on Real data

• Space Shuttle O-ring dataset - Challenger Disaster
• Southern Sea Ice Area
• volcano dataset
• Correlation matrix

Advanced:

• Low level highlighting with hl_loc()

Example - set alternating colours on a data.frame

library(emphatic)
emphatic::hl_opt_global(dark_mode = FALSE)

mtcars %>%
  hl(c('red', 'white')) 

Example 2 - using row and column specification

Use {emphatic} to highlight the mtcars dataset where:

• 6 and 8 cylinder cars only
• colour each row to indicate the miles-per-gallon rating
• do not colour the gear or carb columns
• highlight the car with the maximum miles per gallon in hotpink
• de-emphasise the numeric values to focus on the colour highlighting

mtcars %>%
  hl(ggplot2::scale_colour_viridis_c(), rows = cyl %in% c(6, 8), 
     cols = mpg, dest_cols = mpg:am) %>%
  hl('hotpink', rows = mpg == max(mpg)) %>%
  hl_opt(text_contrast = 0.25)

Example 3 - Rainbows!

mtcars %>% 
  hl(rainbow(32)) %>%
  hl_opt(text_contrast = 0.5)

Example 4: Correlation matrix

Create a correlation matrix of some of the variables in mtcars.

Colour the values using red for negative correlations and blue for positive correlations. Values in-between are coloured using a gradient between red and blue. This colouring is applied using ggplot2::scale_colour_gradient2().

mtcars %>%
  select(cyl, mpg, hp, disp, vs) %>%
  cor() %>%
  hl_matrix(scale_colour_gradient2(), selection = abs(.x) > 0.7 & row(.x) != col(.x)) 

Related Software

• crayon Colored terminal output on terminals that support ‘ANSI’ color and highlight codes. It also works in ‘Emacs’ ‘ESS’. ‘ANSI’ color support is automatically detected.
• fansi Counterparts to R string manipulation functions that account for the effects of ANSI text formatting control sequences.