奧克蘭天氣

在 R 中處理日期與時間

Charlotte Wickham

Instructor

akl_weather_daily.csv

date,max_temp,min_temp,mean_temp,mean_rh,events,cloud_cover
2007-9-1,60,51,56,75,NA,4
2007-9-2,60,53,56,82,Rain,4
2007-9-3,57,51,54,78,NA,6
2007-9-4,64,50,57,80,Rain,6
2007-9-5,53,48,50,90,Rain,7

akl_weather_hourly_2016.csv

year,month,mday,time,temperature,weather,conditions,events,humidity,date_utc
2016,1,1,00:00:00,68,Clear,Clear,NA,68,2015-12-31T11:00:00Z
2016,1,1,00:30:00,68,Clear,Clear,NA,68,2015-12-31T11:30:00Z
2016,1,1,01:00:00,68,Clear,Clear,NA,73,2015-12-31T12:00:00Z
2016,1,1,01:30:00,68,Clear,Clear,NA,68,2015-12-31T12:30:00Z
2016,1,1,02:00:00,68,Clear,Clear,NA,68,2015-12-31T13:00:00Z

make_date(year, month, day)

make_date(year = 2013, month = 2, day = 27)

"2013-02-27"

make_datetime(year, month, day, hour, min, sec) 用於建立 datetime

dplyr 複習

mutate()－新增欄（或覆寫舊欄）
filter()－篩選列
select()－篩選欄
arrange()－排序列
summarise()－彙總列
group_by()－搭配 summarise() 很實用

Pipe %>%

# 不用 pipe：函式巢狀
summarise(group_by(filter(releases, major == 3), minor), n =  n())

# 使用 pipe：流程更直覺
releases %>% 
  filter(major == 3) %>% 
  group_by(minor) %>% 
  summarise(n = n())

一起來練習吧！

在 R 中處理日期與時間