vec2TLmom {lmomco} | R Documentation |
This function converts a vector of trimmed L-moments (TL-moments) to a TL-moment
object of this package. The object is an R list
. This function is intended
to facilitate the use of TL-moments that the user might have from other sources. The
first five TL-moments are supported (λ^{(t)}_1, λ^{(t)}_2, λ^{(t)}_3,
λ_4, λ^{(t)}_5, tau^{(t)}, tau^{(t)}_3, tau^{(t)}_4, and tau^{(t)}_5).
Because in typical practice, the k >= 3 order L-moments are dimensionless ratios
(tau^{(t)}_3, tau^{(t)}_4, and tau^{(t)}_5), this function computes λ^{(t)}_3,
λ^{(t)}_4, λ^{(t)}_5 from λ^{(t)}_2 and the ratios. However, typical
practice is not set on the use of λ^{(t)}_2 or tau^{(t)} as measure of dispersion.
Therefore, this function takes an lscale
optional logical
(TRUE|FALSE
) argument—if λ^{(t)}_2 is provided and lscale=TRUE
, then
tau is computed by the function and if tau is provided, then
λ^{(t)}_2 is computed by the function. The trim level of the TL-moment is required.
vec2TLmom(vec,trim,lscale)
vec |
A vector of L-moment values in λ^{(t)}_1, λ^{(t)}_2 or tau^{(t)}, tau^{(t)}_3, tau^{(t)}_4, and tau^{(t)}_5 order. |
trim |
The trimming level of the TL-moments (can be zero for the ordinary L-moments.) |
lscale |
A logical switch on the type of the second value of first argument.
L-scale (λ_2) or LCV (tau). Default is TRUE ,
the second value in the first argument is λ_2. |
An R list
is returned where t represents the trim
level.
lambdas |
Vector of the TL-moments. First element is λ^{(t)}_1, second element is λ^{(t)}_2, and so on. |
ratios |
Vector of the L-moment ratios. Second element is tau^{(t)}, third element is tau^{(t)}_3 and so on. |
trim |
Level of symmetrical trimming used in the computation. Default is 0—the usual L-moments are returned. |
source |
An attribute identifying the computational source of the L-moments: “TLmoms”. |
It is important to note that the “TL-moment object” returned by TLmoms
is different in structure to that returned by TLmoms
, and similar as the TL-moments should not be confused with the ordinary L-moments. Implementation in the package might change. At present asymmetrical TL-moment construction using this function is not available.s
W.H. Asquith
TL <- vec2TLmom(c(12,0.6,0.34,0.20,0.05),lscale=FALSE,trim=1)