在 R 中添加第二個 y 軸

Question

我設想使用以下數據集創建一個 plot，它將聚集條形圖和折線圖與以下數據相結合：

structure(list(X = 1:14, ORIGIN = c("AUS", "AUS", "DAL", "DAL", 
"DFW", "DFW", "IAH", "IAH", "OKC", "OKC", "SAT", "SAT", "SHV", 
"SHV"), DEST = structure(c(1L, 2L, 1L, 2L, 1L, 2L, 1L, 2L, 1L, 
2L, 1L, 2L, 1L, 2L), .Label = c("ATL", "SEA"), class = "factor"), 
    flight19.x = c(293L, 93L, 284L, 93L, 558L, 284L, 441L, 175L, 
    171L, 31L, 262L, 31L, 175L, 0L), flight19.y = c(5526L, 5526L, 
    6106L, 6106L, 23808L, 23808L, 15550L, 15550L, 2055L, 2055L, 
    3621L, 3621L, 558L, 558L)), row.names = c(NA, -14L), class = "data.frame")

在 Excel 中，我設想的圖表如下所示：

我已經嘗試使用sec.axis function 來生成第二個軸。 但是，結果看起來像 plot 行仍然使用第一個 y 軸而不是第二個軸：

p1 <- ggplot()+
  geom_bar(data = flight19, aes(ORIGIN, flight19.x, fill = DEST),stat = "identity", position = "dodge" )+
  scale_fill_viridis(name = "Destinations", discrete = TRUE)+
  labs(y= "Operation Counts", x = "Airports")


p2 <- p1 + geom_line(data = flight19, aes(as.character(ORIGIN), flight19.y, group = 1))+
  geom_point(data = flight19, aes(as.character(ORIGIN), flight19.y, group = 1))+
  scale_y_continuous(limit = c(0,600),sec.axis = sec_axis(~.*75/10, name = "Total Monthly Operations")) 

plot 顯示以下警告：

Warning messages:
1: Removed 12 row(s) containing missing values (geom_path). 
2: Removed 12 rows containing missing values (geom_point).

代碼生成下面的 plot：

有人可以教我如何讓線 plot 對應於第二軸嗎？ 提前非常感謝。

Answer 1

找到一個合適的變換因子，這里我用 50 只是為了得到漂亮的 y 軸標簽

#create x-axis 
flight19$x_axis <- paste0(flight19$ORIGIN,'\n',flight19$DEST)

# The transformation factor
#transf_fact <- max(flight19$flight19.y)/max(flight19$flight19.x)
transf_fact <- 50

ggplot(flight19, aes(x = x_axis)) +
  geom_bar(aes(y = flight19.x),stat = "identity", fill = "blue") +
  geom_line(aes(y = flight19.y/transf_fact,group=1), color = "orange") + 
  scale_y_continuous(name = "Operation Counts",
                     limit = c(0,600),
                     breaks = seq(0,600,100), 
                     sec.axis = sec_axis(~ (.*transf_fact), 
                                         breaks = function(limit)seq(0,limit[2],5000),
                                         labels = scales::dollar_format(prefix = "$",suffix = " k",scale = .001),
                                         name = "Total Monthly Operations")) + 
  xlab("Airports") + 
  theme_bw()