Manejo de fechas

Para convertir strings a fechas, use `as.Date()`

st1 <- "2018-04-04"
as.Date(st1)

## [1] "2018-04-04"

f1 <- as.Date(c("2019-03-05", "2008-04-04"))
f1

## [1] "2019-03-05" "2008-04-04"

class(f1)

## [1] "Date"

f2 <- as.Date(c("2018/05/23","2017/11/30"))
f2

## [1] "2018-05-23" "2017-11-30"

f3 <- as.Date(32768, origin="1900-01-01") # excel
f3

## [1] "1989-09-19"

f4 <- as.Date(737488, origin="0000-01-01") # mathlab
f4

## [1] "2019-03-05"

f5 <- as.Date(0,origin="1970-01-01") 
f5

## [1] "1970-01-01"

Comparación de fechas

f3 > f4

## [1] FALSE

f3 != f4

## [1] TRUE

Creación de fechas con `ISOdate

ISOdate(2019,3,5,tz="America/Bogota")

## [1] "2019-03-05 12:00:00 -05"

head(OlsonNames()) # nombres de las zonas horarias

## [1] "Africa/Abidjan"     "Africa/Accra"       "Africa/Addis_Ababa"
## [4] "Africa/Algiers"     "Africa/Asmara"      "Africa/Asmera"

isofecha <- ISOdate(2018,12,3,tz="America/Bogota")
class(isofecha)

## [1] "POSIXct" "POSIXt"

as.Date(isofecha)

## [1] "2018-12-03"

as.POSIXct(f1)

## [1] "2019-03-04 19:00:00 -05" "2008-04-03 19:00:00 -05"

Diferencia de días entre dos fechas

dias <- f1[1] - f1[2]
dias

## Time difference of 3987 days

difftime(f1[1],f1[2],units="hours") # se puede escoger la unidad de tiempo

## Time difference of 95688 hours

Sys.Date() #fecha

## [1] "2019-03-25"

Sys.time() # fecha y hora actuales

## [1] "2019-03-25 06:29:27 -05"

Sys.time()-3600 # hace una hora

## [1] "2019-03-25 05:29:27 -05"

Formato para imprimir fechas

Ejemplos de impresión de fechas

hoy <- Sys.Date() # hora actual
hoy # default año, mes, día

## [1] "2019-03-25"

format(hoy, format="%B %d %Y")

## [1] "March 25 2019"

format(hoy, format="%A %d %B %Y")

## [1] "Monday 25 March 2019"

format(hoy, format="%a %d %b %y")

## [1] "Mon 25 Mar 19"

round(Sys.time(), "hour")

## [1] "2019-03-25 06:00:00 -05"

trunc(Sys.time(), "day")

## [1] "2019-03-25 -05"

extracción de fecha y/o hora

format(Sys.time(), "%Y")

## [1] "2019"

format(Sys.Date(),"%a")

## [1] "Mon"

Para conocer el día de la semana, el mes y/o el trimestre para una fecha dada, use `weekdays`, `months` y/o `quarters`

f5 <- as.Date(Sys.Date()+1)
f5

## [1] "2019-03-26"

weekdays(f5)

## [1] "Tuesday"

months(f5)

## [1] "March"

quarters(f5)

## [1] "Q1"

Se pueden generar sucesiones de fechas con `seq`:

seq(Sys.Date(), length.out =5, by="1 day") # por día

## [1] "2019-03-25" "2019-03-26" "2019-03-27" "2019-03-28" "2019-03-29"

seq(Sys.Date(), length.out = 5, by="1 week") # por semana

## [1] "2019-03-25" "2019-04-01" "2019-04-08" "2019-04-15" "2019-04-22"

seq(Sys.Date(), length.out = 5, by="1 month") # por mes

## [1] "2019-03-25" "2019-04-25" "2019-05-25" "2019-06-25" "2019-07-25"

seq(Sys.Date(), length.out = 5, by="1 quarter") #por trimestre

## [1] "2019-03-25" "2019-06-25" "2019-09-25" "2019-12-25" "2020-03-25"

s1 <- seq(Sys.Date(), length.out = 5, by="1 year") # por año

Obtenga estadísticos descriptivos con fechas

min(s1)

## [1] "2019-03-25"

max(s1)

## [1] "2023-03-25"

mean(s1)

## [1] "2021-03-24"

Genere una serie diaria que empiece el 3 de Marzo de 2019 y termine el 10 de Mayo de 2019 sin sábados ni domingos.

suc <- seq(as.Date("2019-03-03"),as.Date("2019-05-10"),"day")
dias <- weekdays(seq(as.Date("2019-03-03"),as.Date("2019-05-10"),"day"))
suc[!(dias == "Sunday" | dias == "Saturday")]

##  [1] "2019-03-04" "2019-03-05" "2019-03-06" "2019-03-07" "2019-03-08"
##  [6] "2019-03-11" "2019-03-12" "2019-03-13" "2019-03-14" "2019-03-15"
## [11] "2019-03-18" "2019-03-19" "2019-03-20" "2019-03-21" "2019-03-22"
## [16] "2019-03-25" "2019-03-26" "2019-03-27" "2019-03-28" "2019-03-29"
## [21] "2019-04-01" "2019-04-02" "2019-04-03" "2019-04-04" "2019-04-05"
## [26] "2019-04-08" "2019-04-09" "2019-04-10" "2019-04-11" "2019-04-12"
## [31] "2019-04-15" "2019-04-16" "2019-04-17" "2019-04-18" "2019-04-19"
## [36] "2019-04-22" "2019-04-23" "2019-04-24" "2019-04-25" "2019-04-26"
## [41] "2019-04-29" "2019-04-30" "2019-05-01" "2019-05-02" "2019-05-03"
## [46] "2019-05-06" "2019-05-07" "2019-05-08" "2019-05-09" "2019-05-10"

Fechas con horas

fh = c("2002-06-09 12:45:40","2003-01-29 09:30:40",
"2002-09-04 16:45:40","2002-11-13 20:00:40",
"2002-07-07 17:30:40")
fh

## [1] "2002-06-09 12:45:40" "2003-01-29 09:30:40" "2002-09-04 16:45:40"
## [4] "2002-11-13 20:00:40" "2002-07-07 17:30:40"

Generación aleatoria de fechas. En este caso escoger 60 días del año 2019 y hacer un histogama.

library(knitr) # para usar `kable()`
set.seed(12345)
fe.aleat <- sample(seq(as.Date('2019/01/01'), as.Date('2019/12/31'), by="1 day"), 60)
hist(fe.aleat, "months", col="orchid",main="Fechas al azar de 2019",freq = TRUE,xlab="Fechas 2019", ylab="Frecuencia")

mean(fe.aleat);sd(fe.aleat)

## [1] "2019-06-24"

## [1] 105.584

kable(table(weekdays(fe.aleat)),format="html",caption = "Dias de la semana",col.names = c("Dia","Frecuencia"))

Dias de la semana
Dia	Frecuencia
Friday	12
Monday	8
Saturday	5
Sunday	8
Thursday	10
Tuesday	11
Wednesday	6

POSIX

z <- Sys.time()
z

## [1] "2019-03-25 06:29:27 -05"

class(z)

## [1] "POSIXct" "POSIXt"

unclass(z)

## [1] 1553513368

unclass(z)/86400

## [1] 17980.48

string <- "2018-11-30"
as.POSIXct(string)

## [1] "2018-11-30 -05"

as.POSIXlt(string)

## [1] "2018-11-30 -05"

unclass(as.POSIXct(string))

## [1] 1543554000
## attr(,"tzone")
## [1] ""

unclass(as.POSIXlt(string))

## $sec
## [1] 0
## 
## $min
## [1] 0
## 
## $hour
## [1] 0
## 
## $mday
## [1] 30
## 
## $mon
## [1] 10
## 
## $year
## [1] 118
## 
## $wday
## [1] 5
## 
## $yday
## [1] 333
## 
## $isdst
## [1] 0
## 
## $zone
## [1] "-05"
## 
## $gmtoff
## [1] NA

Paquete `Lubridate`

library(lubridate)

## 
## Attaching package: 'lubridate'

## The following object is masked from 'package:base':
## 
##     date

ymd(20190318)

## [1] "2019-03-18"

mdy(03202019)

## [1] "2019-03-20"

dmy(21032019)

## [1] "2019-03-21"

llega <- ymd_hms("20190101 12:12:12", tz = "America/Bogota")
llega

## [1] "2019-01-01 12:12:12 -05"

seva <- ymd_hms("20190301 15:15:15", tz = "America/Bogota")
seva

## [1] "2019-03-01 15:15:15 -05"

second(llega)

## [1] 12

wday(seva)

## [1] 6

interval(llega,seva)

## [1] 2019-01-01 12:12:12 -05--2019-03-01 15:15:15 -05

llega %--% seva

## [1] 2019-01-01 12:12:12 -05--2019-03-01 15:15:15 -05

Quiero llamar al señor Suzuki en Tokio el 19 de Marzo de 2019 a las 10:30 am, ¿Qué horas son en Bogotá?

cita <- ymd_hms("20190319 10:30:00", tz = "Asia/Tokyo")
cita

## [1] "2019-03-19 10:30:00 JST"

hora_Bog <- with_tz(cita, "America/Bogota")
hora_Bog

## [1] "2019-03-18 20:30:00 -05"

leap_year(2018)

## [1] FALSE

ymd(20200520) + dyears(1)

## [1] "2021-05-20"

ymd(20200520) + years(1)

## [1] "2021-05-20"

leap_year(2016)

## [1] TRUE

ymd(20160101) + dyears(1)

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

ymd(20160101) + years(1)

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