QDM: QDM (Quantile delta mapping method)

In SBCK: Statistical Bias Correction Kit

QDM (Quantile delta mapping method)

Description

Perform a bias correction.

Details

Mix of delta and quantile method

Methods

Public methods

• QDM$new()

• QDM$fit()

• QDM$predict()

• QDM$clone()

---

Method new()

Create a new QDM object.

Usage

QDM$new(delta = "additive", ...)

Arguments

delta

[character or list] If character : "additive" or "multiplicative". If a list is given, delta[[1]] is the delta transform operator, and delta[[2]] its inverse.

...

[] Named arguments passed to quantile mapping

Returns

A new 'QDM' object.

---

Method fit()

Fit the bias correction method

Usage

QDM$fit(Y0, X0, X1)

Arguments

Y0

[matrix: n_samples * n_features] Observations in calibration

X0

[matrix: n_samples * n_features] Model in calibration

X1

[matrix: n_samples * n_features] Model in projection

Returns

NULL

---

Method predict()

Predict the correction

Usage

QDM$predict(X1, X0 = NULL)

Arguments

X1

[matrix: n_samples * n_features] Model in projection

X0

[matrix: n_samples * n_features or NULL] Model in calibration

Returns

[matrix or list] Return the matrix of correction of X1 if X0 is NULL, else return a list containing Z1 and Z0, the corrections of X1 and X0

---

Method clone()

The objects of this class are cloneable with this method.

Usage

QDM$clone(deep = FALSE)

Arguments

deep

Whether to make a deep clone.

References

Cannon, A. J., Sobie, S. R., and Murdock, T. Q.: Bias correction of simulated precipitation by quantile mapping: how well do methods preserve relative changes in quantiles and extremes?, J. Climate, 28, 6938–6959, https://doi.org/10.1175/JCLI-D-14- 00754.1, 2015.

Examples

## Three bivariate random variables (rnorm and rexp are inverted between ref
## and bias)
XY = SBCK::dataset_gaussian_exp_2d(2000)
X0 = XY$X0 ## Biased in calibration period
Y0 = XY$Y0 ## Reference in calibration period
X1 = XY$X1 ## Biased in projection period

## Bias correction
## Step 1 : construction of the class QDM
qdm = SBCK::QDM$new() 
## Step 2 : Fit the bias correction model
qdm$fit( Y0 , X0 , X1 )
## Step 3 : perform the bias correction, Z is a list containing
## corrections
Z = qdm$predict(X1,X0) 
Z$Z0 ## Correction in calibration period
Z$Z1 ## Correction in projection period

SBCK documentation built on Sept. 11, 2023, 5:10 p.m.