Chapter 2 Working With Dates And Time in R

rm(list = ls())
setwd("C:/Users/Tejendra/Desktop/FoldersOnDesktop/UdemyCourse/Section2")
require(tidyverse)
require(tidymodels)
require(data.table)
require(tidyposterior)
require(tsibble)  #tsibble for time series based on tidy principles
require(fable)  #for forecasting based on tidy principles
require(ggfortify)  #for plotting timeseries
require(forecast)  #for forecast function
require(tseries)
require(chron)
require(lubridate)
require(directlabels)
require(zoo)

# exploring the packages
OlsonNames()

##   [1] "Africa/Abidjan"                   "Africa/Accra"                    
##   [3] "Africa/Addis_Ababa"               "Africa/Algiers"                  
##   [5] "Africa/Asmara"                    "Africa/Asmera"                   
##   [7] "Africa/Bamako"                    "Africa/Bangui"                   
##   [9] "Africa/Banjul"                    "Africa/Bissau"                   
##  [11] "Africa/Blantyre"                  "Africa/Brazzaville"              
##  [13] "Africa/Bujumbura"                 "Africa/Cairo"                    
##  [15] "Africa/Casablanca"                "Africa/Ceuta"                    
##  [17] "Africa/Conakry"                   "Africa/Dakar"                    
##  [19] "Africa/Dar_es_Salaam"             "Africa/Djibouti"                 
##  [21] "Africa/Douala"                    "Africa/El_Aaiun"                 
##  [23] "Africa/Freetown"                  "Africa/Gaborone"                 
##  [25] "Africa/Harare"                    "Africa/Johannesburg"             
##  [27] "Africa/Juba"                      "Africa/Kampala"                  
##  [29] "Africa/Khartoum"                  "Africa/Kigali"                   
##  [31] "Africa/Kinshasa"                  "Africa/Lagos"                    
##  [33] "Africa/Libreville"                "Africa/Lome"                     
##  [35] "Africa/Luanda"                    "Africa/Lubumbashi"               
##  [37] "Africa/Lusaka"                    "Africa/Malabo"                   
##  [39] "Africa/Maputo"                    "Africa/Maseru"                   
##  [41] "Africa/Mbabane"                   "Africa/Mogadishu"                
##  [43] "Africa/Monrovia"                  "Africa/Nairobi"                  
##  [45] "Africa/Ndjamena"                  "Africa/Niamey"                   
##  [47] "Africa/Nouakchott"                "Africa/Ouagadougou"              
##  [49] "Africa/Porto-Novo"                "Africa/Sao_Tome"                 
##  [51] "Africa/Timbuktu"                  "Africa/Tripoli"                  
##  [53] "Africa/Tunis"                     "Africa/Windhoek"                 
##  [55] "America/Adak"                     "America/Anchorage"               
##  [57] "America/Anguilla"                 "America/Antigua"                 
##  [59] "America/Araguaina"                "America/Argentina/Buenos_Aires"  
##  [61] "America/Argentina/Catamarca"      "America/Argentina/ComodRivadavia"
##  [63] "America/Argentina/Cordoba"        "America/Argentina/Jujuy"         
##  [65] "America/Argentina/La_Rioja"       "America/Argentina/Mendoza"       
##  [67] "America/Argentina/Rio_Gallegos"   "America/Argentina/Salta"         
##  [69] "America/Argentina/San_Juan"       "America/Argentina/San_Luis"      
##  [71] "America/Argentina/Tucuman"        "America/Argentina/Ushuaia"       
##  [73] "America/Aruba"                    "America/Asuncion"                
##  [75] "America/Atikokan"                 "America/Atka"                    
##  [77] "America/Bahia"                    "America/Bahia_Banderas"          
##  [79] "America/Barbados"                 "America/Belem"                   
##  [81] "America/Belize"                   "America/Blanc-Sablon"            
##  [83] "America/Boa_Vista"                "America/Bogota"                  
##  [85] "America/Boise"                    "America/Buenos_Aires"            
##  [87] "America/Cambridge_Bay"            "America/Campo_Grande"            
##  [89] "America/Cancun"                   "America/Caracas"                 
##  [91] "America/Catamarca"                "America/Cayenne"                 
##  [93] "America/Cayman"                   "America/Chicago"                 
##  [95] "America/Chihuahua"                "America/Coral_Harbour"           
##  [97] "America/Cordoba"                  "America/Costa_Rica"              
##  [99] "America/Creston"                  "America/Cuiaba"                  
## [101] "America/Curacao"                  "America/Danmarkshavn"            
## [103] "America/Dawson"                   "America/Dawson_Creek"            
## [105] "America/Denver"                   "America/Detroit"                 
## [107] "America/Dominica"                 "America/Edmonton"                
## [109] "America/Eirunepe"                 "America/El_Salvador"             
## [111] "America/Ensenada"                 "America/Fort_Nelson"             
## [113] "America/Fort_Wayne"               "America/Fortaleza"               
## [115] "America/Glace_Bay"                "America/Godthab"                 
## [117] "America/Goose_Bay"                "America/Grand_Turk"              
## [119] "America/Grenada"                  "America/Guadeloupe"              
## [121] "America/Guatemala"                "America/Guayaquil"               
## [123] "America/Guyana"                   "America/Halifax"                 
## [125] "America/Havana"                   "America/Hermosillo"              
## [127] "America/Indiana/Indianapolis"     "America/Indiana/Knox"            
## [129] "America/Indiana/Marengo"          "America/Indiana/Petersburg"      
## [131] "America/Indiana/Tell_City"        "America/Indiana/Vevay"           
## [133] "America/Indiana/Vincennes"        "America/Indiana/Winamac"         
## [135] "America/Indianapolis"             "America/Inuvik"                  
## [137] "America/Iqaluit"                  "America/Jamaica"                 
## [139] "America/Jujuy"                    "America/Juneau"                  
## [141] "America/Kentucky/Louisville"      "America/Kentucky/Monticello"     
## [143] "America/Knox_IN"                  "America/Kralendijk"              
## [145] "America/La_Paz"                   "America/Lima"                    
## [147] "America/Los_Angeles"              "America/Louisville"              
## [149] "America/Lower_Princes"            "America/Maceio"                  
## [151] "America/Managua"                  "America/Manaus"                  
## [153] "America/Marigot"                  "America/Martinique"              
## [155] "America/Matamoros"                "America/Mazatlan"                
## [157] "America/Mendoza"                  "America/Menominee"               
## [159] "America/Merida"                   "America/Metlakatla"              
## [161] "America/Mexico_City"              "America/Miquelon"                
## [163] "America/Moncton"                  "America/Monterrey"               
## [165] "America/Montevideo"               "America/Montreal"                
## [167] "America/Montserrat"               "America/Nassau"                  
## [169] "America/New_York"                 "America/Nipigon"                 
## [171] "America/Nome"                     "America/Noronha"                 
## [173] "America/North_Dakota/Beulah"      "America/North_Dakota/Center"     
## [175] "America/North_Dakota/New_Salem"   "America/Ojinaga"                 
## [177] "America/Panama"                   "America/Pangnirtung"             
## [179] "America/Paramaribo"               "America/Phoenix"                 
## [181] "America/Port-au-Prince"           "America/Port_of_Spain"           
## [183] "America/Porto_Acre"               "America/Porto_Velho"             
## [185] "America/Puerto_Rico"              "America/Punta_Arenas"            
## [187] "America/Rainy_River"              "America/Rankin_Inlet"            
## [189] "America/Recife"                   "America/Regina"                  
## [191] "America/Resolute"                 "America/Rio_Branco"              
## [193] "America/Rosario"                  "America/Santa_Isabel"            
## [195] "America/Santarem"                 "America/Santiago"                
## [197] "America/Santo_Domingo"            "America/Sao_Paulo"               
## [199] "America/Scoresbysund"             "America/Shiprock"                
## [201] "America/Sitka"                    "America/St_Barthelemy"           
## [203] "America/St_Johns"                 "America/St_Kitts"                
## [205] "America/St_Lucia"                 "America/St_Thomas"               
## [207] "America/St_Vincent"               "America/Swift_Current"           
## [209] "America/Tegucigalpa"              "America/Thule"                   
## [211] "America/Thunder_Bay"              "America/Tijuana"                 
## [213] "America/Toronto"                  "America/Tortola"                 
## [215] "America/Vancouver"                "America/Virgin"                  
## [217] "America/Whitehorse"               "America/Winnipeg"                
## [219] "America/Yakutat"                  "America/Yellowknife"             
## [221] "Antarctica/Casey"                 "Antarctica/Davis"                
## [223] "Antarctica/DumontDUrville"        "Antarctica/Macquarie"            
## [225] "Antarctica/Mawson"                "Antarctica/McMurdo"              
## [227] "Antarctica/Palmer"                "Antarctica/Rothera"              
## [229] "Antarctica/South_Pole"            "Antarctica/Syowa"                
## [231] "Antarctica/Troll"                 "Antarctica/Vostok"               
## [233] "Arctic/Longyearbyen"              "Asia/Aden"                       
## [235] "Asia/Almaty"                      "Asia/Amman"                      
## [237] "Asia/Anadyr"                      "Asia/Aqtau"                      
## [239] "Asia/Aqtobe"                      "Asia/Ashgabat"                   
## [241] "Asia/Ashkhabad"                   "Asia/Atyrau"                     
## [243] "Asia/Baghdad"                     "Asia/Bahrain"                    
## [245] "Asia/Baku"                        "Asia/Bangkok"                    
## [247] "Asia/Barnaul"                     "Asia/Beirut"                     
## [249] "Asia/Bishkek"                     "Asia/Brunei"                     
## [251] "Asia/Calcutta"                    "Asia/Chita"                      
## [253] "Asia/Choibalsan"                  "Asia/Chongqing"                  
## [255] "Asia/Chungking"                   "Asia/Colombo"                    
## [257] "Asia/Dacca"                       "Asia/Damascus"                   
## [259] "Asia/Dhaka"                       "Asia/Dili"                       
## [261] "Asia/Dubai"                       "Asia/Dushanbe"                   
## [263] "Asia/Famagusta"                   "Asia/Gaza"                       
## [265] "Asia/Harbin"                      "Asia/Hebron"                     
## [267] "Asia/Ho_Chi_Minh"                 "Asia/Hong_Kong"                  
## [269] "Asia/Hovd"                        "Asia/Irkutsk"                    
## [271] "Asia/Istanbul"                    "Asia/Jakarta"                    
## [273] "Asia/Jayapura"                    "Asia/Jerusalem"                  
## [275] "Asia/Kabul"                       "Asia/Kamchatka"                  
## [277] "Asia/Karachi"                     "Asia/Kashgar"                    
## [279] "Asia/Kathmandu"                   "Asia/Katmandu"                   
## [281] "Asia/Khandyga"                    "Asia/Kolkata"                    
## [283] "Asia/Krasnoyarsk"                 "Asia/Kuala_Lumpur"               
## [285] "Asia/Kuching"                     "Asia/Kuwait"                     
## [287] "Asia/Macao"                       "Asia/Macau"                      
## [289] "Asia/Magadan"                     "Asia/Makassar"                   
## [291] "Asia/Manila"                      "Asia/Muscat"                     
## [293] "Asia/Nicosia"                     "Asia/Novokuznetsk"               
## [295] "Asia/Novosibirsk"                 "Asia/Omsk"                       
## [297] "Asia/Oral"                        "Asia/Phnom_Penh"                 
## [299] "Asia/Pontianak"                   "Asia/Pyongyang"                  
## [301] "Asia/Qatar"                       "Asia/Qostanay"                   
## [303] "Asia/Qyzylorda"                   "Asia/Rangoon"                    
## [305] "Asia/Riyadh"                      "Asia/Saigon"                     
## [307] "Asia/Sakhalin"                    "Asia/Samarkand"                  
## [309] "Asia/Seoul"                       "Asia/Shanghai"                   
## [311] "Asia/Singapore"                   "Asia/Srednekolymsk"              
## [313] "Asia/Taipei"                      "Asia/Tashkent"                   
## [315] "Asia/Tbilisi"                     "Asia/Tehran"                     
## [317] "Asia/Tel_Aviv"                    "Asia/Thimbu"                     
## [319] "Asia/Thimphu"                     "Asia/Tokyo"                      
## [321] "Asia/Tomsk"                       "Asia/Ujung_Pandang"              
## [323] "Asia/Ulaanbaatar"                 "Asia/Ulan_Bator"                 
## [325] "Asia/Urumqi"                      "Asia/Ust-Nera"                   
## [327] "Asia/Vientiane"                   "Asia/Vladivostok"                
## [329] "Asia/Yakutsk"                     "Asia/Yangon"                     
## [331] "Asia/Yekaterinburg"               "Asia/Yerevan"                    
## [333] "Atlantic/Azores"                  "Atlantic/Bermuda"                
## [335] "Atlantic/Canary"                  "Atlantic/Cape_Verde"             
## [337] "Atlantic/Faeroe"                  "Atlantic/Faroe"                  
## [339] "Atlantic/Jan_Mayen"               "Atlantic/Madeira"                
## [341] "Atlantic/Reykjavik"               "Atlantic/South_Georgia"          
## [343] "Atlantic/St_Helena"               "Atlantic/Stanley"                
## [345] "Australia/ACT"                    "Australia/Adelaide"              
## [347] "Australia/Brisbane"               "Australia/Broken_Hill"           
## [349] "Australia/Canberra"               "Australia/Currie"                
## [351] "Australia/Darwin"                 "Australia/Eucla"                 
## [353] "Australia/Hobart"                 "Australia/LHI"                   
## [355] "Australia/Lindeman"               "Australia/Lord_Howe"             
## [357] "Australia/Melbourne"              "Australia/North"                 
## [359] "Australia/NSW"                    "Australia/Perth"                 
## [361] "Australia/Queensland"             "Australia/South"                 
## [363] "Australia/Sydney"                 "Australia/Tasmania"              
## [365] "Australia/Victoria"               "Australia/West"                  
## [367] "Australia/Yancowinna"             "Brazil/Acre"                     
## [369] "Brazil/DeNoronha"                 "Brazil/East"                     
## [371] "Brazil/West"                      "Canada/Atlantic"                 
## [373] "Canada/Central"                   "Canada/Eastern"                  
## [375] "Canada/Mountain"                  "Canada/Newfoundland"             
## [377] "Canada/Pacific"                   "Canada/Saskatchewan"             
## [379] "Canada/Yukon"                     "CET"                             
## [381] "Chile/Continental"                "Chile/EasterIsland"              
## [383] "CST6CDT"                          "Cuba"                            
## [385] "EET"                              "Egypt"                           
## [387] "Eire"                             "EST"                             
## [389] "EST5EDT"                          "Etc/GMT"                         
## [391] "Etc/GMT-0"                        "Etc/GMT-1"                       
## [393] "Etc/GMT-10"                       "Etc/GMT-11"                      
## [395] "Etc/GMT-12"                       "Etc/GMT-13"                      
## [397] "Etc/GMT-14"                       "Etc/GMT-2"                       
## [399] "Etc/GMT-3"                        "Etc/GMT-4"                       
## [401] "Etc/GMT-5"                        "Etc/GMT-6"                       
## [403] "Etc/GMT-7"                        "Etc/GMT-8"                       
## [405] "Etc/GMT-9"                        "Etc/GMT+0"                       
## [407] "Etc/GMT+1"                        "Etc/GMT+10"                      
## [409] "Etc/GMT+11"                       "Etc/GMT+12"                      
## [411] "Etc/GMT+2"                        "Etc/GMT+3"                       
## [413] "Etc/GMT+4"                        "Etc/GMT+5"                       
## [415] "Etc/GMT+6"                        "Etc/GMT+7"                       
## [417] "Etc/GMT+8"                        "Etc/GMT+9"                       
## [419] "Etc/GMT0"                         "Etc/Greenwich"                   
## [421] "Etc/UCT"                          "Etc/Universal"                   
## [423] "Etc/UTC"                          "Etc/Zulu"                        
## [425] "Europe/Amsterdam"                 "Europe/Andorra"                  
## [427] "Europe/Astrakhan"                 "Europe/Athens"                   
## [429] "Europe/Belfast"                   "Europe/Belgrade"                 
## [431] "Europe/Berlin"                    "Europe/Bratislava"               
## [433] "Europe/Brussels"                  "Europe/Bucharest"                
## [435] "Europe/Budapest"                  "Europe/Busingen"                 
## [437] "Europe/Chisinau"                  "Europe/Copenhagen"               
## [439] "Europe/Dublin"                    "Europe/Gibraltar"                
## [441] "Europe/Guernsey"                  "Europe/Helsinki"                 
## [443] "Europe/Isle_of_Man"               "Europe/Istanbul"                 
## [445] "Europe/Jersey"                    "Europe/Kaliningrad"              
## [447] "Europe/Kiev"                      "Europe/Kirov"                    
## [449] "Europe/Lisbon"                    "Europe/Ljubljana"                
## [451] "Europe/London"                    "Europe/Luxembourg"               
## [453] "Europe/Madrid"                    "Europe/Malta"                    
## [455] "Europe/Mariehamn"                 "Europe/Minsk"                    
## [457] "Europe/Monaco"                    "Europe/Moscow"                   
## [459] "Europe/Nicosia"                   "Europe/Oslo"                     
## [461] "Europe/Paris"                     "Europe/Podgorica"                
## [463] "Europe/Prague"                    "Europe/Riga"                     
## [465] "Europe/Rome"                      "Europe/Samara"                   
## [467] "Europe/San_Marino"                "Europe/Sarajevo"                 
## [469] "Europe/Saratov"                   "Europe/Simferopol"               
## [471] "Europe/Skopje"                    "Europe/Sofia"                    
## [473] "Europe/Stockholm"                 "Europe/Tallinn"                  
## [475] "Europe/Tirane"                    "Europe/Tiraspol"                 
## [477] "Europe/Ulyanovsk"                 "Europe/Uzhgorod"                 
## [479] "Europe/Vaduz"                     "Europe/Vatican"                  
## [481] "Europe/Vienna"                    "Europe/Vilnius"                  
## [483] "Europe/Volgograd"                 "Europe/Warsaw"                   
## [485] "Europe/Zagreb"                    "Europe/Zaporozhye"               
## [487] "Europe/Zurich"                    "GB"                              
## [489] "GB-Eire"                          "GMT"                             
## [491] "GMT-0"                            "GMT+0"                           
## [493] "GMT0"                             "Greenwich"                       
## [495] "Hongkong"                         "HST"                             
## [497] "Iceland"                          "Indian/Antananarivo"             
## [499] "Indian/Chagos"                    "Indian/Christmas"                
## [501] "Indian/Cocos"                     "Indian/Comoro"                   
## [503] "Indian/Kerguelen"                 "Indian/Mahe"                     
## [505] "Indian/Maldives"                  "Indian/Mauritius"                
## [507] "Indian/Mayotte"                   "Indian/Reunion"                  
## [509] "Iran"                             "Israel"                          
## [511] "Jamaica"                          "Japan"                           
## [513] "Kwajalein"                        "Libya"                           
## [515] "MET"                              "Mexico/BajaNorte"                
## [517] "Mexico/BajaSur"                   "Mexico/General"                  
## [519] "MST"                              "MST7MDT"                         
## [521] "Navajo"                           "NZ"                              
## [523] "NZ-CHAT"                          "Pacific/Apia"                    
## [525] "Pacific/Auckland"                 "Pacific/Bougainville"            
## [527] "Pacific/Chatham"                  "Pacific/Chuuk"                   
## [529] "Pacific/Easter"                   "Pacific/Efate"                   
## [531] "Pacific/Enderbury"                "Pacific/Fakaofo"                 
## [533] "Pacific/Fiji"                     "Pacific/Funafuti"                
## [535] "Pacific/Galapagos"                "Pacific/Gambier"                 
## [537] "Pacific/Guadalcanal"              "Pacific/Guam"                    
## [539] "Pacific/Honolulu"                 "Pacific/Johnston"                
## [541] "Pacific/Kiritimati"               "Pacific/Kosrae"                  
## [543] "Pacific/Kwajalein"                "Pacific/Majuro"                  
## [545] "Pacific/Marquesas"                "Pacific/Midway"                  
## [547] "Pacific/Nauru"                    "Pacific/Niue"                    
## [549] "Pacific/Norfolk"                  "Pacific/Noumea"                  
## [551] "Pacific/Pago_Pago"                "Pacific/Palau"                   
## [553] "Pacific/Pitcairn"                 "Pacific/Pohnpei"                 
## [555] "Pacific/Ponape"                   "Pacific/Port_Moresby"            
## [557] "Pacific/Rarotonga"                "Pacific/Saipan"                  
## [559] "Pacific/Samoa"                    "Pacific/Tahiti"                  
## [561] "Pacific/Tarawa"                   "Pacific/Tongatapu"               
## [563] "Pacific/Truk"                     "Pacific/Wake"                    
## [565] "Pacific/Wallis"                   "Pacific/Yap"                     
## [567] "Poland"                           "Portugal"                        
## [569] "PRC"                              "PST8PDT"                         
## [571] "ROC"                              "ROK"                             
## [573] "Singapore"                        "Turkey"                          
## [575] "UCT"                              "Universal"                       
## [577] "US/Alaska"                        "US/Aleutian"                     
## [579] "US/Arizona"                       "US/Central"                      
## [581] "US/East-Indiana"                  "US/Eastern"                      
## [583] "US/Hawaii"                        "US/Indiana-Starke"               
## [585] "US/Michigan"                      "US/Mountain"                     
## [587] "US/Pacific"                       "US/Pacific-New"                  
## [589] "US/Samoa"                         "UTC"                             
## [591] "W-SU"                             "WET"                             
## [593] "Zulu"                            
## attr(,"Version")
## [1] "2019a"

### POSIXt classes in R

x = as.POSIXct("2019-12-25 11:45:34")  # nr of seconds
y = as.POSIXlt("2019-12-25 11:45:34")
x

## [1] "2019-12-25 11:45:34 IST"

y  # it gives the same output, but what is behind it?

## [1] "2019-12-25 11:45:34 IST"

unclass(x)

## [1] 1577254534
## attr(,"tzone")
## [1] ""

unclass(y)

## $sec
## [1] 34
## 
## $min
## [1] 45
## 
## $hour
## [1] 11
## 
## $mday
## [1] 25
## 
## $mon
## [1] 11
## 
## $year
## [1] 119
## 
## $wday
## [1] 3
## 
## $yday
## [1] 358
## 
## $isdst
## [1] 0
## 
## $zone
## [1] "IST"
## 
## $gmtoff
## [1] NA

# what does the number mean?
(50 * 365 * 24 * 60 * 60) - (5.5 * 60 * 60)

## [1] 1576780200

y$zone  # extracting the elements from POSIXlt

## [1] "IST"

x$zone  # not possible since it is simply a number of seconds

## Error in x$zone: $ operator is invalid for atomic vectors

# another class based on days
x = as.Date("2019-12-25")
x

## [1] "2019-12-25"

class(x)

## [1] "Date"

unclass(x)

## [1] 18255

50 * 365 - 5  # nr of days since 1970

## [1] 18245

x = chron("12/25/2019", "23:34:09")
x

## [1] (12/25/19 23:34:09)

class(x)

## [1] "chron" "dates" "times"

unclass(x)

## [1] 18255.98
## attr(,"format")
##   dates   times 
## "m/d/y" "h:m:s" 
## attr(,"origin")
## month   day  year 
##     1     1  1970

### strptime
a = as.character(c("1993-12-30 23:45", "1994-11-05 11:43", "1992-03-09 21:54"))
class(a)

## [1] "character"

b = strptime(a, format = "%Y-%m-%d %H:%M")
b

## [1] "1993-12-30 23:45:00 IST" "1994-11-05 11:43:00 IST"
## [3] "1992-03-09 21:54:00 IST"

class(b)

## [1] "POSIXlt" "POSIXt"

### Lets take a look at the package lubridate which has very
### useful time/date data functions different ways in how to
### input dates
ymd(19931123)

## [1] "1993-11-23"

dmy(23111993)

## [1] "1993-11-23"

mdy(11231993)

## [1] "1993-11-23"

# lets use time and date together
mytimepoint <- ymd_hm("1993-11-23 11:23", tz = "Europe/Prague")
mytimepoint

## [1] "1993-11-23 11:23:00 CET"

class(mytimepoint)

## [1] "POSIXct" "POSIXt"

# extracting the components of it
minute(mytimepoint)

## [1] 23

day(mytimepoint)

## [1] 23

hour(mytimepoint)

## [1] 11

year(mytimepoint)

## [1] 1993

month(mytimepoint)

## [1] 11

# we can even change time values within our object
hour(mytimepoint) <- 14
mytimepoint

## [1] "1993-11-23 14:23:00 CET"

# we can take a look at the most common time zones but be
# aware that the time zone recognition also depends on your
# location and machine lets check which day our time point is
wday(mytimepoint)

## [1] 3

wday(mytimepoint, label = T, abbr = F)  # label to display the name of the day, no abbreviation

## [1] Tuesday
## 7 Levels: Sunday < Monday < Tuesday < Wednesday < Thursday < ... < Saturday

# we can calculate which time our timepoint would be in
# another time zone
with_tz(mytimepoint, tz = "Europe/London")

## [1] "1993-11-23 13:23:00 GMT"

mytimepoint

## [1] "1993-11-23 14:23:00 CET"

# time intervals
time1 = ymd_hm("1993-09-23 11:23", tz = "Europe/Prague")
time2 = ymd_hm("1995-11-02 15:23", tz = "Europe/Prague")

# getting the interval
myinterval = interval(time1, time2)
myinterval

## [1] 1993-09-23 11:23:00 CEST--1995-11-02 15:23:00 CET

class(myinterval)  # interval is an object class from lubridate

## [1] "Interval"
## attr(,"package")
## [1] "lubridate"

### Exercise: Creating a Data Frame with lubridate lets now
### build a dataframe with lubridate that contains date and
### time data see the different input formats that are allowed
### in the ymd function

a = c("1998,11,11", "1983/01/23", "1982:09:04", "1945-05-09", 
    19821224, "1974.12.03", 19871210)
a = ymd(a, tz = "CET")
a

## [1] "1998-11-11 CET"  "1983-01-23 CET"  "1982-09-04 CEST" "1945-05-09 CEST"
## [5] "1982-12-24 CET"  "1974-12-03 CET"  "1987-12-10 CET"

# now I am creating a time vector - using different notations
# of input
b = c("22 4 5", "04;09;45", "11:9:56", "23,15,12", "14 16 34", 
    "8 8 23", "21 16 14")
b = hms(b)
b

## [1] "22H 4M 5S"   "4H 9M 45S"   "11H 9M 56S"  "23H 15M 12S" "14H 16M 34S"
## [6] "8H 8M 23S"   "21H 16M 14S"

f = rnorm(7, 10)
f = round(f, digits = 2)
f

## [1]  8.80  9.71 11.25 10.14  9.87  9.44  9.17

date_time_measurement = cbind.data.frame(date = a, time = b, 
    measurement = f)
date_time_measurement

##         date        time measurement
## 1 1998-11-11   22H 4M 5S        8.80
## 2 1983-01-23   4H 9M 45S        9.71
## 3 1982-09-04  11H 9M 56S       11.25
## 4 1945-05-09 23H 15M 12S       10.14
## 5 1982-12-24 14H 16M 34S        9.87
## 6 1974-12-03   8H 8M 23S        9.44
## 7 1987-12-10 21H 16M 14S        9.17

## Calculations with time
minutes(7)

## [1] "7M 0S"

# note that class 'Period' needs integers - full numbers
minutes(2.5)

## Error in validObject(.Object): invalid class "Period" object: periods must have integer values

# getting the duration
dminutes(3)

## [1] "180s (~3 minutes)"

dminutes(3.5)

## [1] "210s (~3.5 minutes)"

# how to add minutes and seconds
minutes(2) + seconds(5)

## [1] "2M 5S"

# more calculations
minutes(2) + seconds(75)

## [1] "2M 75S"

# class 'duration' to perform addition
as.duration(minutes(2) + seconds(75))

## [1] "195s (~3.25 minutes)"

# lubridate has many time classes: period or duration differ!
# which year was a leap year?

leap_year(2009:2014)

## [1] FALSE FALSE FALSE  TRUE FALSE FALSE

ymd(20140101) + years(1)

## [1] "2015-01-01"

ymd(20140101) + dyears(1)

## [1] "2015-01-01"

# lets do the whole thing with a leap year
leap_year(2016)

## [1] TRUE

ymd(20160101) + years(1)

## [1] "2017-01-01"

ymd(20160101) + dyears(1)

## [1] "2016-12-31"

# as you see the duration is the one which is always 365 days
# the standard one (the period) makes the year a whole new
# unit (+1)

## Exercise Lubridate create x, with time zone CET and a given
## time point in 2014 of your choosing I use '2014-04-12
## 23:12' the time point consists of year, months, day and
## hour change now the minute of x to 7 and check x in the
## same line of code see which time it would be in London
## create another time point y in 2015 and get the difference
## between those 2 points

x <- ymd_hm(c("2014-04-12 23:12"), tz = "CET")
minute(x) <- 7
x

## [1] "2014-04-12 23:07:00 CEST"

with_tz(x, tzone = "Europe/London")

## [1] "2014-04-12 22:07:00 BST"

y <- ymd_hm(c("2015-01-01 11:11"), tz = "CET")
y

## [1] "2015-01-01 11:11:00 CET"

y - x

## Time difference of 263.5444 days