Code for plot of R-Ladies growth featured here: https://twitter.com/ledell/status/1095815376598851584

plot_rladies_meetup_growth.R

library("ggplot2")
library("scales")
library("devtools")
install_github("rladies/meetupr", ref = "topic_id")
library("meetupr")  #Requires topic_id branch...
api_key = "API_KEY"  #Use your own meetup.com API key...

meetups <- find_groups(topic_id = 1513883, api_key = api_key)  #all groups tagged with "R-Ladies" topic id
meetups <- meetups[-nrow(meetups), ]  #remove Joburg-R-Users-Group
tc <- find_groups(text = "r ladies twin cities", api_key = api_key) #add Twin Cities
tp <- find_groups(text = "r ladies taipei", api_key = api_key)  #add Taipei
meetups <- rbind(meetups, tc, tp)
meetups[nrow(meetups), "created"] <- as.Date("2014-08-01")  #Fix Taipei date

meetups$Date <- as.POSIXct(meetups$created)
meetups$counts <- rep(1, nrow(meetups))


p <- ggplot(meetups, aes(Date, ..count..)) + 
  geom_histogram() +
  theme_bw(base_size = 14) + xlab(NULL) +
  scale_x_datetime(breaks = date_breaks("3 months"),
                   labels = date_format("%Y-%b"),
                   limits = c(as.POSIXct("2012-01-01"), 
                              as.POSIXct("2019-03-01")) ) +
  geom_vline(xintercept = as.POSIXct("2016-07-01"), col = "purple", size = 2) +
  annotate("text", x = as.POSIXct("2015-03-01"), y = 20, label = "Creation of R-Ladies Global Team/Org \n(useR! 2016)", 
           colour = "purple", size = 5) +
  annotate("text", x = as.POSIXct("2012-10-01"), y = 3, label = "San Francisco", colour = "purple", size = 4) +
  annotate("text", x = as.POSIXct("2016-01-31"), y = 3, label = "London", colour = "purple", size = 4) +
  annotate("text", x = as.POSIXct("2015-04-01"), y = 3, label = "Twin Cities", colour = "purple", size = 4) +
  annotate("text", x = as.POSIXct("2014-08-01"), y = 3, label = "Taipei", colour = "purple", size = 4) +
  theme(axis.text.x = element_text(angle = 45, hjust = 1))
p