在 R 中的 plotly 或 ggplot 中将箭头（或箭头图像）添加到条形图上？

Question

有没有办法根据一些基础信息在条形图的一侧添加箭头图像？

我有以下脚本：

library(tidyverse)
library(plotly)

data <- tibble(url = c("google.com","yahoo.com","yandex.com"), values = c(500,400,300), change = c(0.5,-0.9,0.1))

data

data %>%
  plot_ly(x = data$values,
          y = data$url,
          type = "bar")

这会生成一个简单的条形图，我想在每个条形图旁边添加一些箭头，以显示基于data$change 列的值已经减少或增加。因此，如果数字为正，则箭头朝上并呈绿色，如果为负，则箭头朝下并呈红色

这可能吗？

如果这都不可能 - 有没有办法只覆盖百分比变化的文本而不是条形图旁边？

希望这会出现在一个闪亮的应用程序上，所以即使有一种嵌入或覆盖 html 元素的方法也会很有用！

如果 ggplot 有替代方案，我也会感兴趣。

希望是这样的：

仅更新以下代码：

`library(tidyverse)
library(plotly)

data <- tibble(url = c("google.com","yahoo.com","yandex.com"), values = c(500,400,300), change = c(0.5,-0.9,0.1))

data

data %>%
  plot_ly(x = data$values,
          y = data$url,
          type = "bar")


library(dplyr)
data <- data %>% 
  mutate(x.start = values + 50,
         y.end = seq(0,2,1),
         y.start = y.end + 0.5) %>% 
  mutate(y.start.new = case_when(sign(change) == -1 ~ y.end,
                                 TRUE ~ y.start),
         y.end.new = case_when(sign(change) == -1 ~ y.start,
                               TRUE ~ y.end)
  )


data %>%
  plot_ly(x = data$values,
          y = data$url,
          type = "bar") %>% 
  add_markers(~values, ~url) %>%
  add_annotations(x = ~x.start[change == "up"],
                  y = ~y.start.new[change == "up"],
                  xref = "x", yref = "y",
                  axref = "x", ayref = "y",
                  text = "",
                  showarrow = T,
                  ax = ~x.start[change == "up"],
                  ay = ~y.end.new[change == "up"],
                  arrowcolor = "green") %>% 
  add_annotations(x = ~x.start[change == "down"],
                  y = ~y.start.new[change == "down"],
                  xref = "x", yref = "y",
                  axref = "x", ayref = "y",
                  text = "",
                  showarrow = T,
                  ax = ~x.start[change == "down"],
                  ay = ~y.end.new[change == "down"],
                  arrowcolor = "red")
`

但是您没有产生相同的输出 - 只出现一个箭头？

Answer 1

您可以添加注释。首先指定箭头的开始和结束位置：请注意，在您提供的数据中，您有 yahoo 减少，而不是 yandex 像在您的情节中。

library(dplyr)
data <- data %>% 
  mutate(x.start = values + 50,
         y.end = seq(0,2,1),
         y.start = y.end + 0.5) %>% 
  mutate(y.start.new = case_when(sign(change) == -1 ~ y.end,
                                 TRUE ~ y.start),
         y.end.new = case_when(sign(change) == -1 ~ y.start,
                               TRUE ~ y.end)
         ) %>% 
   mutate(change_dir = case_when(sign(change) == -1 ~ "down",
                                sign(change) == 1 ~ "up"))

然后使用add_annotations进行绘图

data %>%
  plot_ly(x = data$values,
          y = data$url,
          type = "bar") %>% 
  add_markers(~values, ~url) %>%
  add_annotations(x = ~x.start[change_dir == "up"],
                   y = ~y.start.new[change_dir == "up"],
                   xref = "x", yref = "y",
                   axref = "x", ayref = "y",
                   text = "",
                   showarrow = T,
                   ax = ~x.start[change_dir == "up"],
                   ay = ~y.end.new[change_dir == "up"],
                  arrowcolor = "green") %>% 
  add_annotations(x = ~x.start[change_dir == "down"],
                  y = ~y.start.new[change_dir == "down"],
                  xref = "x", yref = "y",
                  axref = "x", ayref = "y",
                  text = "",
                  showarrow = T,
                  ax = ~x.start[change_dir == "down"],
                  ay = ~y.end.new[change_dir == "down"],
                  arrowcolor = "red")