Adding arrows (or image of arrow) onto bar chart in plotly or ggplot in R?

Question

Is there a way to add an arrow image onto the side of a barchart, based on some underlying information?

I have the following script:

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")

This produces a simple bar chart in plotly, I would like to add some arrows next to each bar chart to show that the values have either decreased or increased based on the data$change column. so if the number is positive a arrow turned up and green, if negative, then an arrow that is red and pointed down

Is this possible?

If none of this possible - is there a way to overlay just the text of the percentage change instead next to the bar charts?

Hopefully this would go onto a shiny app, so even if there is a way of embedding or overlaying a html element would be useful!

If there is an alternative in ggplot, I would also be interested.

Hopefully something that looks like this:

JUST TO UPDATE IN REGARDS TO BELOWS ANSWER THE CODE WOULD BE:

`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")
`

But you do not produce the same output - only one arrow appears?

Greg Greg · Accepted Answer · 2020-05-06T17:20:22

You can add annotations. First specify arrow start and end positions: Please note that in the data you provide you have yahoo decreasing, not yandex like in your plot.

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"))

Then plot using add_annotations

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")

Adding arrows (or image of arrow) onto bar chart in plotly or ggplot in R?

1 Answers