# Group by year
# Load dataframe dates.rda with number and dates
# The dataframe is called dates with the variables Nu (number) and FU (date)
# To show the data frame:
dates
# Calculate the year for each date and add to the dataframe:
dates$Year<-strftime(dates$FU,"%Y")
# Now aggregate and all this dates.agg:
dates.agg<-aggregate(Nu~Year,dates,FUN=length)
# To show a table with the number per year:
dates.agg
# And plot a bar chart:
dev.new()
ggplot() +
geom_bar(aes(x = Year,y = Nu),data=dates.agg,colour = '#009933',fill = '#00cc33',stat = 'identity') +
theme_bw() +
ylab(label = 'Number')