BEI_Weights {CSTools} | R Documentation |

## Computing the weights for SFSs using the Best Index PDFs.

### Description

This function implements the computation to obtain the normalized weights for each member of each Seasonal Forecast Systems (SFS) or dataset using the Probability Density Functions (PDFs) indicated by the parameter 'pdf_weight' (for instance the Best Index estimation obtained using the 'PDFBest' function). The weight of each member is proportional to the probability of its index calculated with the PDF "pdf_weight".

### Usage

```
BEI_Weights(index_weight, pdf_weight, time_dim_name = "time")
```

### Arguments

`index_weight` |
Index (e.g. NAO index) array, from a dataset of SFSs for a period of years, with at least dimensions 'member'. Additional dimensions, for instance, a temporal dimension as 'time', must have the same lenght in both parameters, 'index_weight' and 'pdf_weight'. |

`pdf_weight` |
Statistics array to define a Gaussian PDF with at least dimensions 'statistic'. The firt statistic is the parameter 'mean' of the PDF and the second statistic is the parameter 'standard deviation' of the PDF. |

`time_dim_name` |
A character string indicating the name of the temporal dimension, by default 'time'. |

### Value

BEI_Weights() returns a normalized weights array with the same dimensions that index_weight.

### Author(s)

Eroteida Sanchez-Garcia - AEMET, esanchezg@aemet.es

### References

Regionally improved seasonal forecast of precipitation through Best estimation of winter NAO, Sanchez-Garcia, E. et al., Adv. Sci. Res., 16, 165174, 2019, doi: 10.5194/asr-16-165-2019

### Examples

```
# Example for the BEI_Weights function
index_weight <- 1 : (10 * 3 * 5 * 1)
dim(index_weight) <- c(sdate = 10, dataset = 3, member = 5, season = 1)
pdf_weight <- 1 : (10 * 3 * 2 * 1)
dim(pdf_weight) <- c(sdate = 10, dataset = 3, statistic = 2, season = 1)
res <- BEI_Weights(index_weight, pdf_weight)
dim(res)
# sdate dataset member season
# 10 3 5 1
```

*CSTools*version 5.2.0 Index]