library(dplyr)
library(ggplot2)
library(RColorBrewer)

# Create the dataset ----
set.seed(123)
df <- data.frame(helper = c(rnorm(500, 120, 100),
                            rnorm(500, 1, .8))) %>%
    mutate(elapsed = cumsum(helper),
           date = as.POSIXct('2019-05-25 10:00:00') + elapsed,
           event = 'Ping') %>%
    select(date, event)

# Transform the dataset ----
before_after <- df %>%
    arrange(date) %>%
    mutate(before = as.numeric(date - lag(date)),
           after =  as.numeric(lead(date) - date)) %>%
    filter(!is.na(before) & !is.na(after))

# Plot the dataset ----
axis_labels = list('1/100s' = 0.1, '1 sec' = 1, '1 min' = 60,
             '2 min' = 120, '10 min' = 600)
ggplot(before_after, aes(x = before, y = after)) +
    geom_hex() +
    scale_fill_gradientn(colours = rev(brewer.pal(5, "Spectral"))) +
    scale_y_continuous(trans = "log10", minor_breaks = NULL,
                       breaks = unlist(axis_labels),
                       labels = names(axis_labels)) +
    scale_x_continuous(trans = "log10", minor_breaks = NULL,
                       breaks = unlist(axis_labels),
                       labels = names(axis_labels)) +
    theme(axis.text.x = element_text(angle = 45, hjust = 1))