flowunit: Set and retrieve unit of the discharge

In lfstat: Calculation of Low Flow Statistics for Daily Stream Flow Data

Set and retrieve unit of the discharge

Description

In order to compute deficit volumes time series of discharges (either of class 'lfobj' or 'xts') summary.deficit needs to be aware of the unit. Units are stored in the attributes of the time series. flowunit(x) retrieves the current unit from the attributes, flowunit(x) <- value sets a new one.

Usage

flowunit(x)
## S3 method for class 'xts'
flowunit(x)
## S3 method for class 'lfobj'
flowunit(x)

flowunit(x) <- value
## S3 replacement method for class 'xts'
flowunit(x) <- value
## S3 replacement method for class 'lfobj'
flowunit(x) <- value

Arguments

x	The time series, either of class 'lfobj' or 'xts'.
value	a valid character string of length one that can be interpreted as flow unit. See details.

Details

Currently, just a few functions like summary.deficit and lfstat:::plot.deficit_dygraph make use of the unit stored as an attribute.

Usually flow units are of dimension $L^3 T^-1$. Currently a length $l$ can be on of c("metre", "cm", "centimetre" "litre"), whereas time $T$ can be one in c("days", "hours", "mins", "secs"), possibly abbreviated. The numerator of the fraction (everything before the literal "/") is interpreted as the length (superscripts like "^3" are discarded), the denominator as time. E.g. valid units would be "cm^3/s", "m^3/day" or "litre/sec".

Value

A character vector of length one, containing the currently used discharge unit.

Examples

data(ray)
ray <- as.xts(ray)["1970::1970", ]

# currently discharges are in cubic metres per second
flowunit(ray)

# calculating deficit volumes, for fixed threshold 0.001 m^3/s
(s <- summary(find_droughts(ray, threshold = 0.001)))

# multiplying the discharge by 1000 converts is to litre per second
ray$discharge <- ray$discharge * 1000

# changing the unit accordingly, yields the same volumes
flowunit(ray) <- "l/s"
(ss <- summary(find_droughts(ray, threshold = 1)))

identical(s$volume, ss$volume)

lfstat documentation built on Nov. 10, 2022, 5:42 p.m.