display format of xts when time is 00:00

June 14, 2023

How can I change the format of the return value of last if the time of that time step is 00:00?

Here is an example

I have two xts objects containing hourly observations with different end times that I want to align.

library(xts)

x <- c(1:10)
dt <- seq.POSIXt(from = as.POSIXct("2023-06-14 15:00", tz = "GMT"), by = "hour", length.out = 10)
x <- xts(x, order.by=dt)

y <- c(1:12)
dt <- seq.POSIXt(from = as.POSIXct("2023-06-14 15:00", tz = "GMT"), by = "hour", length.out = 12)
y <- xts(y, order.by=dt)

If I print x I get

x
                    [,1]
2023-06-14 15:00:00    1
2023-06-14 16:00:00    2
2023-06-14 17:00:00    3
2023-06-14 18:00:00    4
2023-06-14 19:00:00    5
2023-06-14 20:00:00    6
2023-06-14 21:00:00    7
2023-06-14 22:00:00    8
2023-06-14 23:00:00    9
2023-06-15 00:00:00   10

and when printing y I get

y
                        [,1]
2023-06-14 15:00:00    1
2023-06-14 16:00:00    2
2023-06-14 17:00:00    3
2023-06-14 18:00:00    4
2023-06-14 19:00:00    5
2023-06-14 20:00:00    6
2023-06-14 21:00:00    7
2023-06-14 22:00:00    8
2023-06-14 23:00:00    9
2023-06-15 00:00:00   10
2023-06-15 01:00:00   11
2023-06-15 02:00:00   12

This is all good so far. However, if use last to determine the end of the time series I get a format of the date without time whereas this is not the case when determine the last entry of y:

last(index(x)) 
[1] "2023-06-15 GMT"

last(index(y))
[1] "2023-06-15 02:00:00 GMT"

If I now do the following, y is not subsetted by the extend of x, probably because of the time format:

y[paste(first(index(x)), last(index(x)), sep="/")]
                        [,1]
2023-06-14 15:00:00    1
2023-06-14 16:00:00    2
2023-06-14 17:00:00    3
2023-06-14 18:00:00    4
2023-06-14 19:00:00    5
2023-06-14 20:00:00    6
2023-06-14 21:00:00    7
2023-06-14 22:00:00    8
2023-06-14 23:00:00    9
2023-06-15 00:00:00   10
2023-06-15 01:00:00   11
2023-06-15 02:00:00   12

>Solution :

You could change the format and add the timezone like this:

library(xts)

x <- c(1:10)
dt <- seq.POSIXt(from = as.POSIXct("2023-06-14 15:00", tz = "GMT"), by = "hour", length.out = 10)
x <- xts(x, order.by=dt)

paste0(format(last(index(x)),"%Y-%m-%d %H:%M:%S"), " GMT")
#> [1] "2023-06-15 00:00:00 GMT"

^{Created on 2023-06-14 with reprex v2.0.2}

Note: the output is a character!