Rでお遊び：2月14日だからハートをプロット「plot_a_heart」コマンド

#Githubからソースを読み込み
install.packages("devtools")
devtools::source_url("https://raw.githubusercontent.com/jrozra200/plot_a_heart/master/plot_a_heart.R")

#ハートをプロット
plot_a_heart()

#参考:オリジナルコードとggplot2で描写コードを追加
#塗色:fillオプション
#塗りの透明度:alphaオプション
#テキスト色:textcolorオプション
#テキストの設定;textオプション;初期値"ハート"
#文字種の設定;base_familyオプション;初期値"Meiryo UI"
GGplot_a_heart <- function(fill = "red", alpha = 0.2,
                           text = "ハート", textcolor = "red", base_family = "Meiryo UI"){
  ## R-Code to generate a plot for the following equation
  ## y = x^(2/3) +/- sqrt(1 - x^2), which draws a heart
  ## In plain language, y equals x to the two-thirds plus or minus the 
  ## square-root of one minus x squared
  
  
  ## Generate the x data to be plotted - this creates 20,001 x values
  ## x cannot be less than -1 or greater than 1 (lower or higher will 
  ## create negative values in the square root... a no-no in math)
  tmp <- -1.0
  x <- data.frame()
  
  for (i in 1:20001){
    x[i,1] <- tmp
    tmp <- tmp + (1 / 10000)
  }
  
  ## I've created two y variables - one to handle the "plus" in the plus-
  ## or-minus statement and one to handle the minus.
  y1 <- data.frame()
  y2 <- data.frame()
  
  ## This loop generates the y values - the reason for the if statment is 
  ## for some reason, R did not like the negative values getting raised 
  ## to the 2/3 power
  for(i in 1:20001){
    y1[i,1] <- if(x[i,1] &lt; 0){
      (-x[i,1])^(2/3) + sqrt(1 - x[i,1]^2)
    } else {
      (x[i,1])^(2/3) + sqrt(1 - x[i,1]^2)
    }
    
    y2[i,1] <- if(x[i,1] &lt; 0){
      (-x[i,1])^(2/3) - sqrt(1 - x[i,1]^2)
    } else {
      (x[i,1])^(2/3) - sqrt(1 - x[i,1]^2)
    }
  }
  
  ## combine the values into a single data frame and name them
  final <- cbind(x, y1, y2)
  names(final) <- c("x", "ypos", "yneg")
  
  ## plot the result! I've removed the axes and frame to allow for a 
  ## nicer picture
  #plot(x = final$x, y = final$ypos, ylim = c(-1, 1.5), col = "red", 
  #     xlab = "", ylab = "", axes = FALSE, frame.plot = FALSE)
  #points(x = final$x, y = final$yneg, col = "red")
  
  #ggplotで描写を追記
  ggplot(final, aes(x = x, y = ypos)) +
    geom_ribbon(data = final,
                fill = fill,
                alpha = alpha,
                aes(x = x, y = ypos, ymin = min(final$ypos), ymax = final$ypos)) +
    geom_ribbon(data = final,
                fill = fill,
                alpha = alpha,
                aes(x = x, y = yneg, ymin = final$yneg, ymax = max(final$yneg))) +
    annotate("text", label = text, x = 0, y = max(final$yneg)*.8,
             color = textcolor, size = 10, family = base_family) +
    theme(line = element_blank(),
          text = element_blank(),
          line = element_blank(),
          rect = element_blank())
}

#コマンドの実行
library(ggplot2)
#macでの出力を想定しbase_familyに"HiraKakuProN-W3"設定
GGplot_a_heart(fill = "#a87963", alpha = 0.3, text = "義理チョコです。\n愛を込めて",
               textcolor = "red", base_family = "HiraKakuProN-W3")