imageData (version 0.1-62)

intervalWUI: Calculates water use indices (WUI) over a specified time interval to a data.frame

Description

Calculates the Water Use Index (WUI) between two time points for a set of responses.

Usage

intervalWUI(responses, water.use = "Water.Use", 
            individuals = "Snapshot.ID.Tag", times.factor = "Days", 
            start.times, end.times, suffix.interval = NULL, 
            data, include.total.water = FALSE, na.rm = FALSE)

Value

A data.frame containing the WUIs, the name of each column being the concatenation of one of responses,

WUI and, if not NULL, suffix.interval, the three components being separated by a full stop. If the total water is to be included, the name of the column will be the concatenation of

water.use, Total and the suffix, each separated by a full stop(`.').

Arguments

responses

A character giving the names of the columns in data from which the growth rates are to be calculated.

water.use

A character giving the names of the column in data which contains the water use values.

individuals

A character giving the name(s) of the factor(s) that define the subsets of the data for which each subset corresponds to the responses for an individual.

times.factor

A character giving the name of the column in data containing the factor for times at which the data was collected. Its levels will be used in identifying the intervals and should be numeric values stored as characters.

start.times

A numeric giving the times, in terms of levels of times.factor, that will give a single value for each Snapshot.ID.Tag and that will be taken as the observation at the start of the interval for which the growth rate is to be calculated.

end.times

A numeric giving the times, in terms of levels of times.factor, that will give a single value for each Snapshot.ID.Tag and that will be taken as the observation at the end of the interval for which the growth rate is to be calculated.

suffix.interval

A character giving the suffix to be appended to response to form the names of the columns containing the calculated the growth rates.

data

A data.frame containing the column from which the growth rates are to be calculated.

include.total.water

A logical indicating whether or not to include a column in the results for the total of water.use for the interval for each individual.

na.rm

A logical indicating whether NA values should be stripped before the calculation proceeds.

Author

Chris Brien

Details

The WUI is calculated as the difference between the values of a response at the end.times and start.times divided by the sum of the water use after start.times until end.times. Thus, the water use up to start.times is not included.

See Also

intervalGRaverage, intervalGRdiff, splitValueCalculate, getDates, GrowthRates

Examples

data(exampleData)
Area.smooth.WUI <- intervalWUI("Area", water.use = "Water.Loss", 
                               start.times = 31, end.times = 35, 
                               suffix = "31to35", 
                               data = longi.dat, include.total.water = TRUE)