2018-09-07用R画的几个有趣而无用的东西

是不是以后绘画也可以用R来画了。就像日本的一位老人用Excel画的画也可以一鸣惊人！😝😝

原文见https://fronkonstin.com/2018/09/06/tweetable-mathematical-art-with-r/

I love messing around with R to generate mathematical patterns. I always get surprised doing it and gives me lot of satisfaction. I also learn lot of things doing it: not only about R, but also about mathematics. It is one of my favourite hobbies. Some time ago, I published this post showing some drawings, each of them generated with less than 280 characters of code, to be shared on Twitter. This post came to appear in Hacker News, which provoked an incredible peak on visits to my blog. Some comments in the Hacker News entry are very interesting.

This Summer I delved into this concept of Tweetable Art publishing several drawings together with the R code to generate them. In this post I will show some.

Vertiginous Spiral

I came up with this image inspired by this nice pattern. It is a turtle graphic inspired pattern but instead of drawing lines I use geom_polygon to colour the resulting image in black and white:

image.png

Code:

library(tidyverse)
df <- data.frame(x=0, y=0)
for (i in 2:500){
  df[i,1] <- df[i-1,1]+((0.98)^i)*cos(i)
  df[i,2] <- df[i-1,2]+((0.98)^i)*sin(i)   
}
ggplot(df, aes(x,y)) + 
  geom_polygon(color="white")+
  theme_void()

Slight modifications of the code can generate appealing patterns like this:

image.png

Marine Creature

A combination of sines and cosines. It reminds me a jellyfish:

image.png

Code:

library(tidyverse)
seq(from=-10, to=10, by = 0.05) %>%
  expand.grid(x=., y=.) %>%
  ggplot(aes(x=(x^2+pi*cos(y)^2), y=(y+pi*sin(x)))) +
  geom_point(alpha=.1, shape=20, size=1, color="black")+
  theme_void()+coord_fixed()

summoning Cthulhu

The name is inspired in an answer from Mara Averick to this tweet. It is a modification of the marine creature in polar coordinates:

image.png

Code:

library(tidyverse)
seq(-3,3,by=.01) %>%
  expand.grid(x=., y=.) %>%
  ggplot(aes(x=(x^3-sin(y^2)), y=(y^3-cos(x^2)))) +
  geom_point(alpha=.1, shape=20, size=0, color="white")+
  theme_void()+
  coord_fixed()+
  theme(panel.background = element_rect(fill="black"))+
  coord_polar()

Naive Sunflower

Sunflowers arrange their seeds according a mathematical pattern called phyllotaxis, whic inspires this image. If you want to create your own flowers, you can do this Datacamp’s project. It’s free and will introduce you to the amazing world of ggplot2, my favourite package to create images:

image.png

Code:

library(ggplot2)
a=pi*(3-sqrt(5))
n=500
ggplot(data.frame(r=sqrt(1:n),t=(1:n)*a),
       aes(x=r*cos(t),y=r*sin(t)))+
  geom_point(aes(x=0,y=0),
             size=190,
             colour="violetred")+
  geom_point(aes(size=(n-r)),
             shape=21,fill="gold",
             colour="gray90")+
  theme_void()+theme(legend.position="none")

Silk Knitting

It is inspired by this other pattern. A lot of almost transparent white points ondulating according to sines and cosines on a dark coloured background:

image.png

Code:

library(tidyverse)
seq(-10, 10, by = .05) %>%
  expand.grid(x=., y=.) %>%
  ggplot(aes(x=(x+sin(y)), y=(y+cos(x)))) +
  geom_point(alpha=.1, shape=20, size=0, color="white")+
  theme_void()+
  coord_fixed()+
  theme(panel.background = element_rect(fill="violetred4"))

Try to modify them and generate your own patterns: it is a very funny way to learn R.

Note: in order to make them better readable, some of the pieces of code below may have more than 280 characters but removing unnecessary characters (blanks or carriage return) you can reduce them to make them tweetable.