sst.R

library(tidyverse)
library(httr)
library(rvest)
library(tsibble)
library(jsonlite)
library(feasts)
library(fabletools)


read_temp <- function() { 
  list("Globe"="https://data.giss.nasa.gov/gistemp/tabledata_v4/GLB.Ts+dSST.csv",
      "North"="https://data.giss.nasa.gov/gistemp/tabledata_v4/NH.Ts+dSST.csv", 
      "South"="https://data.giss.nasa.gov/gistemp/tabledata_v4/SH.Ts+dSST.csv") %>% 
  imap_dfr(~readr::read_csv(.x, skip=1, col_select=1:13, na="***") %>% 
              pivot_longer(cols=-1, names_to="Month", values_to="AvTemp") %>% 
              mutate(Date = yearmonth(paste(Year, Month), "%Y %b"), 
                     Region=.y)) %>% 
  as_tsibble(index=Date, key=Region) %>% 
  drop_na() } 

data <- read_temp() %>% 
  model(STL(AvTemp ~ trend(window=120) + season(period=12))) %>% 
  components()


write_csv(data %>% mutate(Date=as.Date(Date)), 
          "data/sst.csv")
write_json(data %>% mutate(Date=as.Date(Date)), 
           "data/sst.json")