sitequant {lmomRFA}

Quantiles and quantile functions for individual sites in a region

Description

Quantiles and quantile functions for individual sites in a region. sitequant computes quantiles directly; siteqfunc returns a function that will compute quantiles.

Usage

sitequant(f, rfd, sitenames, index, drop = TRUE)

siteqfunc(rfd, sitenames, index)

Arguments

f

Vector of probabilities.

rfd

Object of class rfd, containing the specification of a regional frequency distribution.

sitenames

Vector of site names.

index

Values of the site-specific scale factor (“index flood”) for the sites.

drop

Logical: if TRUE and there is only one site, or one probability value, the value returned from sitequant will be a vector rather than a matrix.

Details

If index and sitenames are both present, they must have the same length, and will be taken to refer to sites whose names are the elements of sitename and whose index-flood values are the elements of index.

If index is present and sitenames is missing, quantiles are computed for sites whose index-flood values are the elements of index; if index has names, these names will be used as the site names.

If sitenames is present and index is missing, then quantiles will be computed for a subset of the sites in the region specified by rfd. sitenames will be used to select sites from the vector rfd$index, either by position or by name.

If sitenames and index are both missing, then quantiles will be computed for all of the sites in the region specified by rfd.

Value

For sitequant, a matrix whose rows contain quantiles for a single site, for the probabilities specified in f. If drop is TRUE and the matrix has only one row or column, it will be returned as a vector.

For siteqfunc, a function or a list of functions that each compute quantiles for one site. Each function takes a single argument, a vector of probabilities, and returns a vector of quantiles.

Author(s)

J. R. M. Hosking [e-mail]

Examples

rfit <- regfit(Cascades, "gno")   # Fit regional distribution

## Quantiles for:
# - sites in the Cascades data set, indexed by number
sitequant(c(0.9, 0.99, 0.999), rfit, sitenames=1:3)

# - sites in the Cascades data set, indexed by name
sitequant(c(0.9, 0.99, 0.999), rfit,
  sitenames=c("350304", "351433", "351862"))

# - other sites, with specified index floods
sitequant(c(0.9, 0.99, 0.999), rfit, index=c(80, 100))

# - other sites, with specified index floods and names
sitequant(c(0.9, 0.99, 0.999), rfit, index=c(80, 100),
  sitenames=c("Site 80", "Site 100"))

# - a single site, with drop=FALSE: result is a matrix
sitequant(c(0.9, 0.99, 0.999), rfit, sitenames=10, drop=FALSE)

# - a single site, with drop=TRUE (the default): result is a vector
sitequant(c(0.9, 0.99, 0.999), rfit, sitenames=10)

# Quantile function for site 10
qfunc10 <- siteqfunc(rfit, site=10)

# Compute quantiles via the quantile function
qfunc10(c(0.9, 0.99, 0.999))

# Plot the quantile function
evplot(qfunc=qfunc10)