DC meetup visits.R

setwd('~/Downloads')
dat <- read.csv('VennDiagrams2-data.csv', stringsAsFactors=F)
for(u in c('visited','joined')){
  dat[[u]] <- as.Date(dat[[u]])
}

library(plyr)
library(reshape2)
library(chron)
dat$monthly = paste(months(as.chron(dat$visited)), years(as.chron(dat$visited)))

visits = ddply(dat, ~monthly+groupName, summarise, count=length(member_id))
visits <- transform(visits, monthly = as.Date(paste('1',monthly), format='%d %b %Y'), groupName=as.factor(groupName))
library(ggplot2)
ggplot(subset(visits, monthly >= as.Date('2013-01-01')), 
       aes(x=monthly, y=count, 
           group=factor(groupName), color=factor(groupName)))+
  geom_line()+
  labs(x='', y='Number of visits',color='Program')+
  ggtitle('2013') + 
  theme(legend.position=c(0.2, 0.65))