R plotly histogram hover text - r

Question

This is my code. Just a simple historgram. But what I wanted to do is to customize the hover text so that when I hover, it will display all species included in that histogram bar. Can you help me?
iris %>%
plot_ly(x=~Sepal.Length, color=~Sepal.Width, text=~Species) %>%
add_histogram()
Here's the output. But when I hover it seems the text is only displaying the first species in the table.
plotly_hist

Answer 1

I'm not sure whether this is possible. Probably you are demanding too much from plotly. After trying some options I think there are two ways to go if you want the different Species to show up in the tooltip:
First option is to use a stacked histogram using hovermode = "unified" like so:
library(plotly)
fig <- plot_ly()
fig <- fig %>% add_trace(data = filter(iris, Species == "setosa"),
x = ~Sepal.Length,
color = ~Species,
text = ~Species,
type='histogram',
bingroup=1, showlegend = FALSE)
fig <- fig %>% add_trace(data = filter(iris, Species == "versicolor"),
x = ~Sepal.Length,
color = ~Species,
text = ~Species,
type='histogram',
bingroup=1, showlegend = FALSE)
fig <- fig %>% add_trace(data = filter(iris, Species == "virginica"),
x = ~Sepal.Length,
color = ~Species,
text = ~Species,
type='histogram',
bingroup=1, showlegend = FALSE)
fig <- fig %>% layout(
hovermode="unified",
barmode="stack",
bargap=0.1)
fig
The second option would be to make the computations yourself, i.e. binning and summarising and to make a bar chart of the counts.
iris %>%
mutate(Sepal.Length.Cut = cut(Sepal.Length, breaks = seq(4, 8, .5), right = FALSE)) %>%
group_by(Sepal.Length.Cut, Species) %>%
summarise(n = n(), Sepal.Width = sum(Sepal.Width)) %>%
tidyr::unite("text", Species, n, sep = ": ", remove = FALSE) %>%
summarise(n = sum(n), Sepal.Width = sum(Sepal.Width) / n, text = paste(unique(text), collapse = "\n")) %>%
plot_ly(x = ~Sepal.Length.Cut, y = ~n, text = ~text) %>%
add_bars(marker = list(colorscale = "Rainbow"), hovertemplate = "%{y}<br>%{text}")
Edit A third option would be to use ggplotly(). This way it is an easy task to add annotations displayling the total numbers per bin. This way we can make use of the stats layers in ggplot2 which will do all the computations. To the best of my knowledge that couldn't be done that easily using "pure" plotly.
library(plotly)
ggplot(iris, aes(Sepal.Length, fill = Species)) +
stat_bin(breaks = seq(4, 8, .5), closed = "left") +
stat_bin(breaks = seq(4, 8, .5), closed = "left", geom = "text", mapping = aes(Sepal.Length, label = ..count..), inherit.aes = FALSE, vjust = -.5) +
theme_light()
ggplotly()