Date

date<-as.Date('2017/09/02')
date

## [1] "2017-09-02"

date2<-as.Date('2017/11/10')
date2

## [1] "2017-11-10"

result<-date2-date
result

## Time difference of 69 days

dtime<-difftime(date,date2,unit="weeks")
dtime

## Time difference of -9.857143 weeks

sum<-date+10
sum

## [1] "2017-09-12"

v1<-as.Date(c('2015/09/02','2016/09/03','2017/08/01'))
diff(v1)

## Time differences in days
## [1] 367 332

v2<-as.Date(c('2017/09/02','2017/10/03','2017/11/10'))
diff(v2)

## Time differences in days
## [1] 31 38

dt<-seq(date,length=6,by="week")
dt

## [1] "2017-09-02" "2017-09-09" "2017-09-16" "2017-09-23" "2017-09-30"
## [6] "2017-10-07"

dt2<-seq(date,length=6,by="2 week")
dt2

## [1] "2017-09-02" "2017-09-16" "2017-09-30" "2017-10-14" "2017-10-28"
## [6] "2017-11-11"

dt3<-seq(date,length=10,by=20 )
dt3

##  [1] "2017-09-02" "2017-09-22" "2017-10-12" "2017-11-01" "2017-11-21"
##  [6] "2017-12-11" "2017-12-31" "2018-01-20" "2018-02-09" "2018-03-01"

dt4 <- as.Date("04/20/2011", format = "%m/%d/%Y")
dt4

## [1] "2011-04-20"

dt5 <- as.Date("October 6, 2010", format = "%B %d, %Y")
dt5

## [1] "2010-10-06"

unclass(dt4)

## [1] 15084

oldClass(dt5)

## [1] "Date"

inherits(dt4, what = "", which = FALSE)

## [1] FALSE

tm1 <- as.POSIXct("2013-07-24 23:55:26")
tm1

## [1] "2013-07-24 23:55:26 IST"

tm2 <- as.POSIXct("25072013 08:32:07", format = "%d%m%Y %H:%M:%S")
tm2

## [1] "2013-07-25 08:32:07 IST"

tm3 <- as.POSIXct("2010-12-01 11:42:03", tz = "GMT")
tm3

## [1] "2010-12-01 11:42:03 GMT"

tm2 > tm1

## [1] TRUE

tm1 + 30

## [1] "2013-07-24 23:55:56 IST"

tm1 - 14

## [1] "2013-07-24 23:55:12 IST"

tm2 - tm1

## Time difference of 8.611389 hours

as.POSIXct("2013-03-10 08:32:07") - as.POSIXct("2013-03-09 23:55:26")

## Time difference of 8.611389 hours

Sys.time()

## [1] "2017-10-02 09:12:36 IST"

unclass(tm1)

## [1] 1374690326
## attr(,"tzone")
## [1] ""

tm1.lt <- as.POSIXlt("2013-07-24 23:55:26")
tm1.lt

## [1] "2013-07-24 23:55:26 IST"

unclass(tm1.lt)

## $sec
## [1] 26
## 
## $min
## [1] 55
## 
## $hour
## [1] 23
## 
## $mday
## [1] 24
## 
## $mon
## [1] 6
## 
## $year
## [1] 113
## 
## $wday
## [1] 3
## 
## $yday
## [1] 204
## 
## $isdst
## [1] 0
## 
## $zone
## [1] "IST"
## 
## $gmtoff
## [1] NA

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