Add posixlt as new column to dataframe
I am generating some random numbers:
data <- matrix(runif(10, 0, 1), ncol = 2)
dataframe <- data.frame(data)
> dataframe
X1 X2
1 0.7981783 0.13233858
2 0.9592338 0.05512942
3 0.1812384 0.74571334
4 0.1447498 0.96656930
5 0.1735390 0.37345575
and I want to create a corresponding timestamp column and bind it to the above dataframe.
time <- as.POSIXlt(runif(10, 0, 60), origin = "2017-05-05 10:00:00")
This creates 10 values.
> time
[1] "2017-05-05 13:00:27 EEST" "2017-05-05 13:00:02 EEST" "2017-05-05 13:00:26 EEST" "2017-05-05 13:00:25 EEST" "2017-05-05 13:00:28 EEST"
[6] "2017-05-05 13:00:17 EEST" "2017-05-05 13:00:35 EEST" "2017-05-05 13:00:08 EEST" "2017-05-05 13:00:29 EEST" "2017-05-05 13:00:32 EEST"
Now I want to bind it to a dataframe, so first I decided to make it a matrix:
time <- matrix(time, nrow = 5, ncol = 2)
but this gives me:
Warning message:
In matrix(time, nrow = 5, ncol = 2) :
data length [11] is not a sub-multiple or multiple of the number of rows [5]
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The reason is because it POSIXlt
stores the date time as an attribute list
, whereas it POSIXct
won't. Thus, it is better to useas.POSIXct
time <- as.POSIXct(runif(10, 0, 60), origin = "2017-05-05 10:00:00")
If we need to save, this can be done as list
ofdata.frame
data.frame(date1= time[1:5], date2 = time[6:10])
without converting to matrix
, because "Datetime" is forced into storage mode integer
when converting to matrix
.
Suppose we go to POSIXlt
, then find list
attributes
time1 <- as.POSIXlt(runif(10, 0, 60), origin = "2017-05-05 10:00:00")
unclass(time1)
#$sec
# [1] 13.424695 40.860449 57.756890 59.072140 24.425521 39.429729 58.309546
# [8] 6.294982 46.613436 25.444415
#$min
# [1] 30 30 30 30 30 30 30 30 30 30
#$hour
# [1] 15 15 15 15 15 15 15 15 15 15
#$mday
# [1] 5 5 5 5 5 5 5 5 5 5
#$mon
# [1] 4 4 4 4 4 4 4 4 4 4
#$year
# [1] 117 117 117 117 117 117 117 117 117 117
#$wday
# [1] 5 5 5 5 5 5 5 5 5 5
#$yday
# [1] 124 124 124 124 124 124 124 124 124 124
#$isdst
# [1] 0 0 0 0 0 0 0 0 0 0
#$zone
# [1] "IST" "IST" "IST" "IST" "IST" "IST" "IST" "IST" "IST" "IST"
#$gmtoff
# [1] 19800 19800 19800 19800 19800 19800 19800 19800 19800 19800
#attr(,"tzone")
#[1] "" "IST" "IST"
C POSIXct
is the integer storage values that can be found withunclass
unclass(time)
#[1] 1493978445 1493978451 1493978432 1493978402 1493978447 1493978441
#[7] 1493978445 1493978450 1493978419 1493978425
#attr(,"tzone")
#[1] ""
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