This package provides functions to simplify application of forecast verification metrics to large datasets of ensemble forecasts. The design goals of `easyVerification`

are:

**Flexibility:**a variety of data structures are supported**Ease of use:**Absolute forecasts and observations are converted to category and probability forecasts based on the threshold or probability (e.g. terciles) provided, ouputs are reformatted to fit the input**Convenience and flexibility over speed:**R's built-in vectorisation is used where possible but more importantly, new metrics should be easy to implement

The forecast metrics are imported from the `SpecsVerification`

package. Additional verification metrics not available through `SpecsVerification`

are implemented directly. At the time of publication, the package offers functionality to compute the following deterministic and probabilitistic scores and skill scores:

- Mean error (
`EnsMe`

), mean absolute error(`EnsMae`

), mean squared error (`EnsMse`

), and root mean squared error (`EnsRmse`

) of the ensemble mean and their skill scores (e.g.`EnsRmsess`

) - Correlation with the ensemble mean (
`EnsCorr`

) - Spread to error ratio (
`EnsSprErr`

and`FairSprErr`

) - Area under the ROC curve (
`EnsRoca`

) and its skill score (`EnsRocss`

) - Fair (
`FairRps`

) and standard (`EnsRps`

) rank probability scores and skill scores (e.g.`FairRpss`

) - Fair (
`FairCrps`

) and standard (`EnsCrps`

) continuous ranked probability scores and skill scores (e.g.`FairCrpss`

) - Dressed scores (
`DressIgn`

,`DressCrps`

) and their skill scores (`DressIgnSs`

,`DressCrpss`

) with default ensemble dressing method ("silverman") - The generalized discrimination score for ensembles (
`Ens2AFC`

)

Additional forecast verification metrics can be added by the user following the examples above.

You can get the latest version from CRAN

```
install.packages("easyVerification")
```

You can get the latest development version using

```
devtools::install_github("MeteoSwiss/easyVerification")
```

You can find out more about the package and its functionality in the vignette.

```
vignette('easyVerification')
```

The following example illustrates how to compute the continous ranked probability skill score of an ensemble forecast:

```
suppressPackageStartupMessages(library(easyVerification))
## check out what is included in easyVerification
ls(pos="package:easyVerification")
#> [1] "convert2prob" "count2prob" "Ens2AFC" "EnsCorr"
#> [5] "EnsError" "EnsErrorss" "EnsMae" "EnsMaess"
#> [9] "EnsMe" "EnsMess" "EnsMse" "EnsMsess"
#> [13] "EnsRmse" "EnsRmsess" "EnsRoca" "EnsRocss"
#> [17] "EnsSprErr" "FairSprErr" "toyarray" "toymodel"
#> [21] "veriApply"
## set up the forecast and observation data structures
## assumption: we have 13 x 5 spatial instances, 15 forecast
## times and 51 ensemble members
tm <- toyarray(c(13,5), N=15, nens=51)
fo.crpss <- veriApply("EnsCrpss", fcst=tm$fcst, obs=tm$obs)
## if the data are organized differently such that forecast
## instance and ensemble members are NOT the last two array
## dimensions, this has to be indicated
## alternative setup:
## forecast instance, ensemble members, all forecast locations
## collated in one dimension
fcst2 <- array(aperm(tm$fcst, c(3,4,1,2)), c(15, 51, 13*5))
obs2 <- array(aperm(tm$obs, c(3,1,2)), c(15, 13*5))
fo2.crpss <- veriApply("EnsCrpss", fcst=fcst2, obs=obs2,
ensdim=2, tdim=1)
## The forecast evaluation metrics are the same, but the
## data structure is different in the two cases
dim(fo.crpss$crpss)
#> [1] 13 5
dim(fo2.crpss$crpss)
#> [1] 65
range(fo.crpss$crpss - c(fo2.crpss$crpss))
#> [1] 0 0
```

As of `easyVerification 0.1.7.0`

, parallel processing is supported under *NIX systems. The following minimal example illustrates how to use the parallel processing capabilities of `easyVerification`

.

```
## generate a toy-model forecast observation set of
## 10 x 10 forecast locations (e.g. lon x lat)
tm <- toyarray(c(10,10))
## run and time the ROC skill score for tercile forecasts without parallelization
system.time({
tm.rocss <- veriApply("EnsRocss", tm$fcst, tm$obs, prob=1:2/3)
})
#> user system elapsed
#> 1.984 0.008 2.000
## run the ROC skill score with parallelization
system.time({
tm.rocss.par <- veriApply("EnsRocss", tm$fcst, tm$obs, prob=1:2/3, parallel=TRUE)
})
#> Loading required namespace: parallel
#> [1] "Number of CPUs 3"
#> user system elapsed
#> 0.088 0.040 0.824
```

To get additional help and examples please see the vignette `vignette('easyVerification')`

or the help pages of the functions in `easyVerification`

(e.g. `help(veriApply)`

).

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