ggplot2で折れ線グラフ + 複数のグラフを並べる

ggplot_sample.R

library(ggplot2)
library(reshape2) # melt()用
library(grid) ; library(gridBase) # 複数の図の配置 cf. http://d.hatena.ne.jp/dichika/20110116/1295183973

country_list = c("Egypt", "Armenia", 
                 "Afghanistan", "Azerbaijan", "Bosnia", "Cambodia", "Croatia",
                 "Eritrea", "Kazakhstan", "South Africa", "Vietnam")
for (country in country_list){
  aid_amount <- AidData[AidData$recipient==country, c("Aid_All", "year", "p4_polity2", "Giniall")] # 全ての援助額
  
  # ggplot2 描画レイヤー /AidAll
  g <- ggplot(
    aid_amount,
    aes(
      x = year,
      y = Aid_All,
      #group = id,
      #colour = type
    )
  )
  g <- g + geom_line()
  g <- g + theme_bw() # 白色背景に灰色グリッドのテーマ
  g <- g + theme(axis.text.x = element_text(size=12), 
                axis.title.x = element_text(size=15), 
                axis.text.y = element_text(size=12), 
                axis.title.y = element_text(size=15),
                axis.ticks.y = element_blank(),
                plot.title = element_text(size = rel(1.4))) # グラフタイトルのサイズ
  g <- g + labs(title = paste(country, ": Aid_All", sep=""))
  
  # ggplot2 描画レイヤー / Polity and Inequality
  aid_amount <- AidData[AidData$recipient==country, c("Aid_All", "year", "p4_polity2", "Giniall")] # 全ての援助額
  aid_amount$Giniall <- aid_amount$Giniall / 10 # rescale
  aid_amount <- melt(aid_amount, id="year", measure=c("Giniall", "p4_polity2")) # ggplot用に変形
  g2 <- ggplot(aid_amount,
               aes(x=year,
                   y=value,
                   colour=variable,
                   group=variable)) + geom_line()
  #g2 <- g2 + guides(colour = guide_legend(reverse = TRUE)) # 凡例の順番を合わせる
  g2 <- g2 + scale_colour_discrete(name="Values", # colour, fill, shapeの使い分けがよくわからず。今回は線に対応してだったからcolour? 
                                                  # cf.http://www.cookbook-r.com/Graphs/Legends_(ggplot2)/
                                  breaks=c("Giniall", "p4_polity2"),
                                  labels=c("Inequality(Gini)", "Polity"))
  g2 <- g2 + labs(title = country, x="year", y="values") 
  g2 <- g2 + theme_bw() # 白色背景に灰色グリッドのテーマ
  
  
  filename = paste("AidAllGraph_", country, ".pdf", sep = "")
  pdf(filename,width=10,height=4.25)
  #plot.new()
  # 複数グラフの描画 cf. http://d.hatena.ne.jp/dichika/20110116/1295183973  ４分割なども可能
  grid.newpage() #空の画面を作る
  pushViewport(viewport(layout=grid.layout(1, 2))) #画面を区切る（今回は1行2列の2分割）
  print(g, vp=viewport(layout.pos.row=1, layout.pos.col=1)) #1行目の1列
  print(g2, vp=viewport(layout.pos.row=1, layout.pos.col=2)  ) #1行目の2列
  dev.off()
} #close for(country)