TITLE: ASCII charts in R
DATE: 2021-04-30
AUTHOR: John L. Godlee
====================================================================


I was inspired by a blog post on Gemini that was talking about 
uploading gemtext summaries of their academic research. The writer 
of the post wanted to avoid images where simple ASCII graphics 
would do, so I had a look to see if I could make simple ASCII 
scatter charts. Most of the answers on this Stackoverflow post 
mention using gnuplot, with varying degrees of hackery to get 
around how difficult gnuplot is to work with. I use R for nearly 
all my basic data visualisation, so I decided instead to write a 
script in R. The {txtplot} package has done the bulk of the real 
work already. I only had to write a wrapper that makes it 
convenient to pass values from the command line:

  [Stackoverflow post]: 
https://stackoverflow.com/questions/123378/command-line-unix-ascii-b
ased-charting-plotting-tool
  [{txtplot}]: 
https://cran.r-project.org/web/packages/txtplot/index.html

    #!/usr/bin/env Rscript

    args <- commandArgs(trailingOnly=TRUE)

    argsLen <- length(args)

    if (argsLen > 3) stop("Too many arguments")
    if (argsLen < 1) stop("Must supply CSV with two columns")

    infile <- args[1]

    if (argsLen == 2) {
      pwidth <- round(as.numeric(args[2])) 
    } else {
      pwidth <- round(options()$width*0.8) 
    }

    if (argsLen == 3) {
      pheight <- round(as.numeric(args[3])) 
    } else { 
      pheight <- round(0.25*pwidth)
    }

    if (!file.exists(infile)) {
      stop("File path invalid")
    }

    dat <- read.csv(infile)

    if (ncol(dat) != 2) {
      stop("CSV must have only two columns")
    }

    txtplot::txtplot(dat[,1], dat[,2], 
      width = pwidth, height = pheight,
      xlab = names(dat)[1], ylab = names(dat)[2])

Here is an example. First the base R plot of the data:

  ![Base R scatter 
plot](https://johngodlee.xyz/img_full/asciichart/plot.png)

And now the ASCII representation, generated with asciichart 
test.csv:

            +------+---------+--------+---------+---------+--------+
    C       |                                * *         *      *  |
    u 8e+06 +                         *                     **     +
    m       |                               *      *      *        |
    u       |                             *** **   * ***           |
    l 6e+06 +                               ****      * **         +
    a       |                  *   ************   *  *  *  *       |
    t 4e+06 +          *       *     ******* * **      *           +
    i       |             * * ** **** * **   **  *     *           |
    v       |           *  *********** ****** ** *                 |
    e 2e+06 +             *********  ** **                         +
    .       |    **   **********  * **                             |
    m     0 + * ******* **      *             *                    +
    o       +------+---------+--------+---------+---------+--------+
                   5        10       15        20        25
                                 Layer.diversity