Split out time interval in time series in r

Question

I have a dataset - time series Data below:

Col 1(End): 
2018.01.01 01:00:00
2018.01.01 02:00:00
2018.01.01 03:00:00
2018.01.01 04:00:00
2018.01.01 05:00:00
2018.01.01 06:00:00
2018.01.01 07:00:00
2018.01.01 08:00:00
2018.01.01 09:00:00
2018.01.01 10:00:00
2018.01.01 11:00:00
2018.01.02 01:00:00
2018.01.02 02:00:00
2018.01.02 03:00:00
2018.01.02 04:00:00

Col 2(Price-indexed) 
55.09
44.02
44.0
33
43
43
33
33

I wish to select from the data the time of 11:00 every day I have tried doing a sequence but with daylight saving in GMT it changes to 12 in October fro 2019 and 2020 which is not correct

datos_2019_2020<-read.csv("DayaheadPricesfull_2019_2020.csv")
#price variable changed to numeric

datos_2019_2020$Price_indexed=as.numeric(datos_2019_2020$Price)

time_index_2019_2020 <- seq(from = as.POSIXct("2019-01-01 00:00"), to = as.POSIXct("2020-12-31 23:00"), by = "hour",tz="GMT")

eventdata_2019_2020 <- as.xts(datos_2019_2020$Price_indexed, drop = FALSE,order.by = time_index_2019_2020)
df.new_2019_2020 = eventdata_2019_2020[seq(12, nrow(eventdata_2019_2020), 24), ]

Answer 1

Using the xts object x shown reproducibly in the Note at the end:

x[format(time(x), format = "%H:%M:%S") == "11:00:00"]

giving this xts object:

                    [,1]
2018-01-01 11:00:00   NA

Time zone problems are often specific to a particular installation but often the problem is between local time and GMT or due to the switch between standard and daylight savings time. In these cases it often easiest to just set the entire session to GMT making the local time GMT. In that case there will be no confusion between local and GMT since they are both GMT and GMT does not have daylight savings time.

Sys.setenv(TZ = 'GMT')

Note

Lines1 <- "
2018.01.01 01:00:00
2018.01.01 02:00:00
2018.01.01 03:00:00
2018.01.01 04:00:00
2018.01.01 05:00:00
2018.01.01 06:00:00
2018.01.01 07:00:00
2018.01.01 08:00:00
2018.01.01 09:00:00
2018.01.01 10:00:00
2018.01.01 11:00:00
2018.01.02 01:00:00
2018.01.02 02:00:00
2018.01.02 03:00:00
2018.01.02 04:00:00"

Lines2 <- "
55.09
44.02
44.0
33
43
43
33
33"

library(xts)
col1 <- read.table(text = Lines1, sep = ",")
col2 <- read.table(text = Lines2)
# merge col1 and col2 using NA's to fill in
m <- merge(col1, col2, by = 0, all.x = TRUE)
z <- read.zoo(m[-1], tz = "", format = "%Y.%m.%d %H:%M:%S")
x <- as.xts(z)