inst/ggplot_histogram_by_month.R

In chiefmurph/mondate: Keep track of dates in terms of months

library(ggplot2)
library(scales)

# load data:
log <- data.frame(Date = as.Date(c("2013/05/25","2013/05/28","2013/05/31",
                                   "2013/06/01","2013/06/02","2013/06/05",
                                   "2013/06/07")), 
                  Quantity = c(9,1,15,4,5,17,18))
log
str(log)
log$Month <- as.Date(cut(log$Date,
                         breaks = "month"))
log$Week <- as.Date(cut(log$Date,
                        breaks = "week",
                        start.on.monday = FALSE)) # changes weekly break point to Sunday
log
ggplot(data = log,
       aes(Month, Quantity)) +
  stat_summary(fun.y = sum, # adds up all observations for the month
               geom = "bar") + # or "line"
  scale_x_date(
    labels = date_format("%Y-%m"),
    breaks = "1 month") # custom x-axis labels
# graph by week:
ggplot(data = log,
       aes(Week, Quantity)) +
  stat_summary(fun.y = sum, # adds up all observations for the week
               geom = "bar") + # or "line"
  scale_x_date(
    labels = date_format("%Y-%m-%d"),
    breaks = "1 week") # custom x-axis labels