R AUC with ROCR from Biomod2

Question

I have to get AUC (area under the ROC curve) to evaluate my models. I am using the SRE model with Biomod2 package.

Biomod2 gives me AUC value through evaluate() function which is nice. Then I tried to check AUC with ROCR package, and I got a big problem : AUC values from evaluate() (Biomod2) and ROCR weren't the same. (For some other models not implemented on Biomod2, I have to use ROCR package so that's why I am anxious.)

Now I am trying to find the problem using a reproducible example (code from Biomod2 package), but I get an error.

First, the code from Biomod2 package (reproducible example):

     library(biomod2)
     library(ROCR)

     # species occurrences
     DataSpecies <- read.csv(system.file("external/species/mammals_table.csv",
                                package="biomod2"), row.names = 1)
     head(DataSpecies)

     # the name of studied species
     myRespName <- 'GuloGulo'

     # the presence/absences data for our species 
     myResp <- as.numeric(DataSpecies[,myRespName])

     # the XY coordinates of species data
     myRespXY <- DataSpecies[,c("X_WGS84","Y_WGS84")]


     # Environmental variables extracted from BIOCLIM (bio_3, bio_4,     bio_7, bio_11 & bio_12)
     myExpl = stack( system.file( "external/bioclim/current/bio3.grd", 
                         package="biomod2"),
            system.file( "external/bioclim/current/bio4.grd", 
                         package="biomod2"), 
            system.file( "external/bioclim/current/bio7.grd", 
                         package="biomod2"),  
            system.file( "external/bioclim/current/bio11.grd", 
                         package="biomod2"), 
            system.file( "external/bioclim/current/bio12.grd", 
                         package="biomod2"))

     # 1. Formatting Data
     myBiomodData <- BIOMOD_FormatingData(resp.var = myResp,
                                 expl.var = myExpl,
                                 resp.xy = myRespXY,
                                 resp.name = myRespName)

     # 2. Defining Models Options using default options.
     myBiomodOption <- BIOMOD_ModelingOptions()

     # 3. Doing Modelisation

     myBiomodModelOut <- BIOMOD_Modeling( myBiomodData, 
                                 models = c('SRE'), 
                                 models.options = myBiomodOption, 
                                 NbRunEval=1, 
                                 DataSplit=80, 
                                 Yweights=NULL, 
                                 VarImport=3, 
                                 models.eval.meth = c('TSS'),
                                 SaveObj = TRUE,
                                 rescal.all.models = FALSE,
                                 do.full.models = FALSE,
                                 modeling.id='test')

     # 4. Evaluate model over another dataset (here the full one)

     ## creation of suitable dataset
     data <- cbind(GuloGulo=get_formal_data(myBiomodModelOut,'resp.var'), 
                   get_formal_data(myBiomodModelOut,'expl.var'))

     ## evaluation
     evaluate(myBiomodModelOut, data=data, stat=c('ROC','TSS'))

Then, the part to get AUC from ROCR :

    # 4.1 Projection on current environemental conditions

    myBiomodProjection <- BIOMOD_Projection(modeling.output = myBiomodModelOut,
                                    new.env = myExpl,
                                    proj.name = 'current',
                                    selected.models = 'all',
                                    binary.meth = 'TSS',
                                    compress = FALSE,
                                    build.clamping.mask = FALSE)


    myBiomod_raster <- get_predictions(myBiomodProjection) #, as.data.frame=TRUE


    spp_occ <- myResp
    sauv_p <- as.vector(as.matrix(myBiomod_raster))

    ROC_curve <- data.frame(result=sauv_p, spp=spp_occ) #préparation
    ROC_curve <- prediction(ROC_curve$result, ROC_curve$spp) #run

    AUC <- performance( ROC_curve, "auc" )@y.values
    print(AUC[[1]])

The problem I have is I can't create a data.frame from myResp and myBiomod_raster, because length(myResp) = 2488 and length for myBiomod_raster is 5640.

The error is : Arguments imply differing number of rows

Do you know how I could do to have the same number of rows, using the datas from this Biomod2 package example?

Thanks a lot!