Plotly R : how to add dynamic annotation which belongs to frame - r

Question

I'm struggeling on a simple task. I have a database with 3 columns :
Year (numeric)
Age (numeric)
Pop (numeric)
Part60 : The % of individuals with age >= 60 (string like '% of poeple over 60 : 12%'). This value is the same for each rows of a year.
Dataset looks like :
I built a plotly bargraph with a frame based on the year. So I have a slider which allow me to show for each age the number of individuals and this is animated year by year.
I would like to add an anotation which shows the value of Part60 for the year of the frame... I know that it's possible with a ggplot sent to ggplotly function, however I want to do it from scratch with a plot_ly function as parameters are (for me) easier to control and follow the logic of my code.
This is my code :
gH <- plot_ly(data = dataH,
name = 'Hommes',
marker = list(color = ispfPalette[4]),
x = ~Pop,
y = ~Age,
frame = ~Annee)
gH <- gH %>% layout(yaxis = list(categoryorder="array",
categoryarray=dataH$Age))
gH <- gH %>% layout(yaxis = list(title = '',
zeroline = TRUE,
showline = TRUE,
showticklabels = TRUE,
showgrid = FALSE),
xaxis = list(title = '',
zeroline = TRUE,
showline = TRUE,
autorange = "reversed"),
shapes = hline(60))
gH <- gH %>% add_annotations(
x = 3000,
y = 62,
text = 'Part des 60 ans et + : 12 %',
showarrow = F,
color = ispfPalette[8]
Where text = 'Part des 60 ans et + : 12 %' should be replaced by something which allow me to get the value which belongs to the year of the slider.
Is someone may help me to do it ?
Thanks in advance for your great help.

Answer 1

Since I don't have your data, it's pretty difficult to give you the best answer. Although, here is a method in which you can add text that changes throughout the animation.
library(plotly)
library(tidyverse)
data(gapminder, package = "gapminder")
str(gapminder)
funModeling::df_status(gapminder)
# continent, lifeExp, year
gap <- gapminder %>% group_by(year, continent) %>%
summarise(Expectancy = mean(lifeExp))
# plot
p1 <- plot_ly(gap, x = ~Expectancy, y = ~continent,
frame = ~year, type = 'bar',
showlegend = F,
hovertemplate = paste0("Continent: %{y}<br>",
"<extra></extra>"),
texttemplate = "Life Expectancy: %{x:.2f}") %>%
layout(yaxis=list(title=""),
xaxis=list(title="Average Life Expectancy per Continent By Year"),
title=list(text=paste("Fancy Title")),
margin = list(t = 100))
p1
If you had text you wanted to animate that is not connected to each marker (bar, point, line), then you could do it this way.
# Something to add in the annotation text
gap2 <- gap %>% filter(continent == "Asia") %>%
droplevels() %>%
arrange(year)
# build to see frames
p2 <- plotly_build(p1)
# modify frames; need an annotation for each frame
# make sure the data is in order by year (order by frame)
lapply(1:nrow(gap2), # for each frame
function(i){
annotation = list(
data = gap2,
type = "text",
x = 77,
y = .5,
yref = "paper",
showarrow = F,
text = paste0("Asian Life Expectancy<br>",
sprintf("%.2f", gap2[i, ]$Expectancy)),
font = list(color = "#b21e29", size = 16))
p2$x$frames[[i]]$layout <<- list(annotations = list(annotation)) # change plot
})
p2
If anything is unclear, let me know.