Irregular Zoo -> Regular Zoo

It takes an irregular zoo object (with non-existing values for some dates) and converts it into a regularly spaced zoo object within the time period defined by from and to, by filling the missing dates with ‘NA’

Usage

izoo2rzoo(x, ...)

# S3 method for default
izoo2rzoo(x, from= start(x), to= end(x), 
                   date.fmt, tstep, tz, ...)
     
# S3 method for zoo
izoo2rzoo(x, from= start(x), to= end(x), 
                   date.fmt, tstep, tz, ...)

Arguments

x

irregular zoo object (vector or matrix) representing a time series (very likely read with some user-defined procedure, and with some missing values for particular days/months/years)

from

Character indicating the starting date for creating the regularly spaced zoo object. The default value corresponds to the date of the first element of x
It has to be in the format indicated by date.fmt.

to

Character indicating the ending date for creating the regularly spaced zoo object. The default value corresponds to the date of the last element of x
It has to be in the format indicated by date.fmt.

date.fmt

character indicating the format in which the dates are stored in from and to, e.g. %Y-%m-%d. See ‘Details’ section in strptime. By default, date.fmt is missing, and it is automatically set to %Y-%m-%d when time(x) is Date object, and set to %Y-%m-%d %H:%M:%S when x is a sub-daily zoo object.

tstep

character, indicating the time step used for creating the time sequence going from from to to that will be used as time(x)
Valid values are (but not limited to) hours, days, months, years. By default, tstep is missing, and it is automatically set to "minutes" when sfreq(x) is min, to "hours" when sfreq(x) is hourly, to "days" when sfreq(x) is daily, to "weeks" when sfreq(x) is weekly, to "months" when sfreq(x) is monthly, to "quarters" when sfreq(x) is quarterly, and to "years" when sfreq(x) is annual.

tz

character, with the specification of the time zone used for from, to. System-specific (see time zones), but "" is the current time zone, and "GMT" is UTC (Universal Time, Coordinated). See Sys.timezone and as.POSIXct.

If tz is missing (the default), it is automatically set to the time zone used in time(x).

This argument can be used when working with sub-daily zoo objects to force using time zones other than the local time zone for from and to. It should be used with caution, being well aware of the time zone of the data. See examples.

...

further arguments passed to or from other methods

Details

If the full time period of x is a subset of the time period defined by from and to, the time period of the resulting zoo is the one defined by from and to, assigning 'NA' to all the dates in which x do not have a value.

Value

a regularly spaced zoo object, with values given by x and time stamps going from from to to at intervals defined by tsteps

Author

Mauricio Zambrano-Bigiarini, mzb.devel@gmail

Examples

##
## Example 1: Adding NA for February 29th to an existing zoo object

# dummy values and dates (February 29th is not present !)
x <- 1:9
dates <- c("1964-02-25", "1964-02-26", "1964-02-27", "1964-02-28", "1964-03-01", 
           "1964-03-02", "1964-03-03", "1964-03-04", "1964-03-05")

# From 'character' to 'Date' class
dates <- as.Date(dates)

## From 'numeric' to 'zoo' class
( x <- zoo(x, dates) ) # Feb 29th is still not present in 'x'
## checking the length of 'x'
length(x) # 9 elements (there is no data for Feb 29th)

## Adding a missing value (NA in this case) for Feb 29th
( y <- izoo2rzoo(x) )

## checking the new length
length(y) # 1 element more than the original 'x' (thre is an NA value in Feb 29th)


##
## Example 2: Extending the original 'x' object from February 1st to the end of March, 
#             assigning 'NA' to the days in which 'x' do not have a value.
( y <- izoo2rzoo(x, from="1964-02-01", to="1964-03-31") )


##
## Example 3: Working with a zoo matrix with two identical 'x' time series, 
##            from 1964-02-25 to 1964-03-05
( Y <- cbind(x,x) )

# Adding a missing value (NA in this case) for Feb 29th in all the columns of Y
( rY <- izoo2rzoo(Y) )


##
## Example 4: Working with hourly data, from 01:00 to 10:00 UTC on 12th December 2000
dates  <- ISOdatetime(year=2000, month=12, day=12, hour=1:10, min=0, sec=0, tz="UTC")
values <- 1:10
x      <- zoo(values, dates)

# removing four values in 'x', from 02:00 to 05:00, i.e., they will not be present 
# anymore in 'x' at all, not even NA !)
x <- x[-c(2:5)]
time(x)
length(x)

# Adding missing values (NA in this case) from 02:00 to 05:00
y <-  izoo2rzoo(x)
time(y)
length(y)


##
## Example 5: Extending hourly data to a DateTime before 'start(x)', 
##            specifying only the date.
##            Time of 'x' is in local time zone (tz="") instead of UTC
dt <- hip("2021-01-01 00:00:00", "2021-01-01 20:00:00", tz="")
x  <- zoo(0:20, dt)
(y  <- izoo2rzoo(x, from="2020-12-31") )# 00:00:00 is ommited


##
## Example 6: Extending hourly data to a DateTime before 'start(x)', 
##            specifying date and time.
##            Time of 'x' is in local time zone (tz="") instead of UTC
dt <- hip("2021-01-01 00:00:00", "2021-01-01 20:00:00", tz="")
x  <- zoo(0:20, dt)
( y  <- izoo2rzoo(x, from="2020-12-31 20:00:00") )


##
## Example 7: Extending hourly data to a DateTime after 'end(x)', 
##            specifying date and time.
##            Time of 'x' is in local time zone (tz="") instead of UTC
dt <- hip("2021-01-01 00:00:00", "2021-01-01 20:00:00", tz="")
x  <- zoo(0:20, dt)
( y  <- izoo2rzoo(x, to="2021-01-02 12:00:00") )


##
## Example 8: Extending hourly data to a DateTime before 'start(x)'.
##            Note that the 'tz' argument can be ommited in the 'hip' function, 
##            because by default it assumes UTC as time zone
dt <- hip("2021-01-01 00:00:00", "2021-01-01 20:00:00", tz="UTC")
x  <- zoo(0:20, dt)
( y  <- izoo2rzoo(x, from="2020-12-31 20:00:00", tz="UTC") )


##
## Example 9: Extending hourly data to a date before 'start(x)'. However, hourly 'x'
##            values are given at HH:15:00 hours instead of HH:00:00 hours.

## Loading the time series of hourly streamflows for the station Karamea at Gorge
## Time Zone for 'KarameaAtGorgeQts' data is GMT+12 (see ?KarameaAtGorgeQts)
data(KarameaAtGorgeQts)
x <- KarameaAtGorgeQts

# Subsetting 'x' to its first day only
# (01/Jan/1980 08:15:00 - 01/Jan/1980 23:15:00)
x <- window(x, end="1980-01-01 23:59:00")

# Adding NA hourly data since 1979-12-31 21:15:00
izoo2rzoo(x, from="1979-12-31 21:15:00", tz="GMT+12")