Viewing hover info for overlapping scatter points in Plotly R - r

Question

I was surpised I was not able to google this solution, so I thought i'd put up a post. Surely others have the same issue...
The issue I have is that when two or more scatter points overlap (i.e. same x and y), the hover information only shows the info of the top point.
Example:
df <- data.frame(ID=1:6, x=c(5:9, 7), y=c(1:5, 3)+10, info=paste('Hover information: ',c(LETTERS[c(1:6)])))
df
plot_ly(df) %>%
add_trace(x = ~x,
y = ~y,
type = 'scatter',
mode = 'markers',
marker = list(color = 1:6,
symbol = 1:6,
size = 25),
hoverinfo = "text",
text = df$info)
It is possible to make BOTH hoverinfo for the middle point to show up? Possibly as:
Hover information: C
Hover information: F

Answer 1

You can try to use add_markers() and jitter, e.g:
plot_ly(df) %>%
add_markers(x = ~jitter(x, 1),
y = ~jitter(y, 1),
type = 'scatter',
mode = 'markers',
marker = list(color = 1:6,
symbol = 1:6,
size = 25),
hoverinfo = "text",
text = ~info)
But to get multiple information as you designed, maybe you need to modify your dataframe (but you will lose the colour code):
df$info <- as.character(df$info)
df$combined_info[1] <- df$info[1]
for(i in 2:nrow(df)){
df$combined_info[i] <- df$info[i]
for(j in 2:i-1){
if((df$x[j] == df$x[i]) && (df$y[j] == df$y[i])){
df$combined_info[i] <- paste0(df$combined_info[j], "<br>",
df$info[i])
}
}
}
And then you can use the original plotly code, while changing the "text" argument:
plot_ly(df) %>%
add_trace(x = ~x,
...
text = ~combined_info)