Calendar plot of UFO sightings, 2000--2013

tidytuesday-190625-ufo.R

#===============================================================================
# 2019-07-12 -- tidytuesday
# Data on UFO sightings ,2019-06-25
# Ilya Kashnitsky, ilya.kashnitsky@gmail.com
#===============================================================================

# load required packages
library(tidyverse)
library(janitor)
library(sf)
library(lubridate)
library(magrittr)
library(hrbrthemes); import_roboto_condensed()


# the data
ufo_sightings <- readr::read_csv("https://raw.githubusercontent.com/rfordatascience/tidytuesday/master/data/2019/2019-06-25/ufo_sightings.csv")

# create time variables using lubridate
df <- ufo_sightings %>% 
    mutate(
        date_time = date_time %>% parse_date_time('mdy_HM'),
        month = date_time %>% month(label = TRUE) %>% as.factor(),
        year = date_time %>% year(),
        day = date_time %>% day(),
        week = date_time %>% week(),
        wday = date_time %>% wday(week_start = 1, label = TRUE),
        date_documented = date_documented %>% parse_date_time('mdy'),
        gap_doc = as.duration(date_documented - date_time) / 
            as.duration(years(1))
)


# calendar plot of sighting tolls by day

df %>% 
    filter(year %in% 2000:2013) %>% 
    group_by(year, day) %>% 
    mutate(cases = n()) %>% 
    ggplot(aes(week, wday, fill = cases))+
    geom_tile()+
    scale_fill_viridis_c("# UFO\nsightings\nper day",option = "B")+
    scale_x_continuous(breaks = c(1:9, 20, 30, 52))+
    facet_grid(year~month, scales = "free")+
    theme_minimal(base_family = font_rc)+
    theme(panel.grid = element_blank())+
    labs(x = "week of the year", y = NULL,
         title = "Numbers of reported UFO sightings in the World",
         caption = "Data: The National UFO Reporting Center; tidytuesday\nhttps://raw.githubusercontent.com/rfordatascience/tidytuesday/master/data/2019/2019-06-25/ufo_sightings.csv")+
    theme(axis.text.y = element_text(size = 7),
          plot.title = element_text(size = 30, face = 2))

# save
ggsave("ufo-calendar.pdf", width = 10, height = 10, device = cairo_pdf)