subdaily2weekly: Subdaily -> Weekly

Description

Generic function for transforming a DAILY (or sub-daily) regular time series into a WEEKLY one

Usage

subdaily2weekly(x, ...)
# S3 method for default
subdaily2weekly(x, FUN, na.rm=TRUE, na.rm.max=0,
           start="00:00:00", start.fmt= "%H:%M:%S", tz, ...)
# S3 method for zoo
subdaily2weekly(x, FUN, na.rm=TRUE, na.rm.max=0,
           start="00:00:00", start.fmt= "%H:%M:%S", tz, ...)
# S3 method for data.frame
subdaily2weekly(x, FUN, na.rm=TRUE, na.rm.max=0,
           start="00:00:00", start.fmt= "%H:%M:%S", tz,
           dates=1, date.fmt = "%Y-%m-%d %H:%M:%S",  
           out.fmt="zoo", verbose=TRUE, ...)
# S3 method for matrix
subdaily2weekly(x, FUN, na.rm=TRUE, na.rm.max=0,
           start="00:00:00", start.fmt= "%H:%M:%S", tz,
           dates=1, date.fmt = "%Y-%m-%d %H:%M:%S",  
           out.fmt="zoo", verbose=TRUE, ...)

Value

a zoo object with weekly time frequency

Arguments

x

zoo, data.frame or matrix object, with (sub)daily time series.
Measurements at several gauging stations can be stored in a data.frame or matrix object, and in that case, each column of x represents the time series measured in each gauging station, and the column names of x have to correspond to the ID of each station (starting by a letter).

FUN

Function that have to be applied for transforming from daily to weekly time step (e.g., for precipitation FUN=sum and for temperature and streamflow ts FUN=mean).

FUN MUST accept the na.rm argument, because na.rm is passed to FUN.

na.rm

Logical. Should missing values be removed?
-) TRUE : the weekly values are computed only for weeks with a percentage of missing values less than na.rm.max
-) FALSE: if there is AT LEAST one NA within a month, the corresponing weekly values in the output object will be NA.

na.rm.max

Numeric in [0, 1]. It is used to define the maximum percentage of missing values allowed in each month to keep the weekly aggregated value in the output object of this function. In other words, if the percentage of missing values in a given month is larger or equal than na.rm.max the corresponding weekly value will be NA.

start

character, indicating the starting time used for aggregating sub-daily time series into daily ones. It MUST be provided in the format specified by start.fmt.
This value is used to define the time when a new day begins (e.g., for some rain gauge stations).
-) All the values of x with a time attribute before start are considered as belonging to the day before the one indicated in the time attribute of those values.
-) All the values of x with a time attribute equal to start are considered to be equal to "00:00:00" in the output zoo object.
-) All the values of x with a time attribute after start are considered as belonging to the same day as the one indicated in the time attribute of those values.

It is useful when the daily values start at a time different from "00:00:00". Use with caution. See examples.

start.fmt

character indicating the format in which the time is provided in start, By default date.fmt=%H:%M:%S. See format in as.POSIXct.

tz

character, with the specification of the time zone used in both x and start. 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 to force using the local time zone or any other time zone instead of UTC as time zone.

dates

numeric, factor or Date object indicating how to obtain the dates for each gauging station
If dates is a number (default), it indicates the index of the column in x that stores the dates
If dates is a factor, it is converted into Date class, using the date format specified by date.fmt
If dates is already of Date class, the code verifies that the number of days on it be equal to the number of elements in x

date.fmt

character indicating the format in which the DateTime objects are stored in dates, e.g. %Y-%m-%d %H:%M:%S. See format in as.POSIXct.
ONLY required when class(dates)=="factor" or class(dates)=="numeric".

out.fmt

OPTIONAL. Only used when x is a matrix or data.frame object /cr character, for selecting if the result will be a matrix/data.frame or a zoo object. Valid values are: numeric, zoo.

verbose

logical; if TRUE, progress messages are printed

...

arguments additional to na.rm passed to FUN.

Author

Mauricio Zambrano-Bigiarini, mzb.devel@gmail

Examples

Run this code

######################
## Ex1: Computation of WEEKLY values from HOURLY ts, removing any missing value in 'x'

## Loading the HOURLY streamflows for the station Karamea at Gorge
data(KarameaAtGorgeQts)
x <- KarameaAtGorgeQts

# Sub-daily to weekly ts
subdaily2weekly(x, FUN=mean, na.rm=TRUE)

if (FALSE) {
######################
## Ex2: Computation of WEEKLY values from HOURLY ts, only when the percentage of NAs in 
#       each week is lower than a user-defined percentage (10

## Loading the HOURLY streamflows for the station Karamea at Gorge
data(KarameaAtGorgeQts)
x <- KarameaAtGorgeQts

# Subsetting 'x' to its first three weeks 
# (Monday 2nd December 1985 - Sunday 29th uanuary 20th 1980)
x <- window(x, end="1985-12-31 23:59:00")

## Transforming into NA the 10
set.seed(10) # for reproducible results
n           <- length(x)
n.nas       <- round(0.1*n, 0)
na.index    <- sample(1:n, n.nas)
x[na.index] <- NA

## Daily to Weekly, only for weeks with less than 10
( w2 <- subdaily2weekly(x, FUN=sum, na.rm=TRUE, na.rm.max=0.1) )

# Verifying that the second and third month of 'x' had 10
cmv(x, tscale="weekly")

######################
## Ex3: Computation of WEEKLY values from HOURLY ts, removing any missing value in 'x'
#       Loading the HOURLY streamflows for the station Karamea at Gorge
data(KarameaAtGorgeQts)
x <- KarameaAtGorgeQts

# Sub-daily to weekly ts
subdaily2weekly(x, FUN=mean, na.rm=TRUE)
}