Drawing a Fish Curve using R and ggplot2


Recently, I wondered whether there is a way to draw a fish shape using a mathematical function. Since I did not find a ready-made R function, I tried to write the function by myself. The equations, I've used for writing this function can be found on WolframMathWorld.

The function

The fish_curve() function requires the ggplot2 and the dplyr package. It creates a data frame with two variables (x and y) and 10.000 observations. Finally, the data points are plotted using ggplot2.

fish_curve <- function(colour='black', size = 5){
    x = cos(1:10000) - sin(1:10000)^2 / sqrt(2),
    y = cos(1:10000) * sin(1:10000)
  ) %>%
    ggplot(., aes(x, y)) +
    geom_point(colour = colour, size = size) +

Function call with default parameters

With colour and size the fish_curve() function allows the user to specify two parameters; that is colour and size of the plotted points. The default values are black for colour and 5 for size.

(p1 <- fish_curve())

plot of chunk fish-1


In the following example, we customize colour and size of the fish shape:

(p2 <- fish_curve(colour = 'blue', size = 1))

plot of chunk fish-2

And finally, we place the two plots side by side using the patchwork package:

p1 + p2

plot of chunk unnamed-chunk-1

Author: norbert

Biometrician at Clinical Trial Centre, Leipzig University (GER), with degrees in sociology (MA) and public health (MPH).

Leave a Reply

Fill in your details below or click an icon to log in:

WordPress.com Logo

You are commenting using your WordPress.com account. Log Out /  Change )

Twitter picture

You are commenting using your Twitter account. Log Out /  Change )

Facebook photo

You are commenting using your Facebook account. Log Out /  Change )

Connecting to %s

This site uses Akismet to reduce spam. Learn how your comment data is processed.

%d bloggers like this: