predByCV {BioMM} | R Documentation

## Cross validation prediction by supervised machine learning and feature selection

### Description

Prediction by supervised machine learning models using cross validation along with feature selection methods.

### Usage

    predByCV(data, repeats, nfolds, FSmethod, cutP, fdr,
      FScore = MulticoreParam(), classifier, predMode, paramlist,
      innerCore = MulticoreParam())

### Arguments

`data` | The input dataset. The first column is the label or the output. For binary classes, 0 and 1 are used to indicate the class member.
`repeats` | The number of repeats used for cross validation. Repeated cross validation is performed if N >=2.
`nfolds` | The number of folds is defined for cross validation.
`FSmethod` | Feature selection methods. Available options are c(NULL, 'positive', 'wilcox.test', 'cor.test', 'chisq.test', 'posWilcox', or 'top10pCor').
`cutP` | The cutoff used for p value thresholding. Commonly used cutoffs are c(0.5, 0.1, 0.05, 0.01, etc). The default is 0.05.
`fdr` | Multiple testing correction method. Available options are c(NULL, 'fdr', 'BH', 'holm', etc). See also `p.adjust`. The default is NULL.
`FScore` | The number of cores used for feature selection if parallel computing needed.
`classifier` | Machine learning classifiers.
`predMode` | The prediction mode. Available options are c('probability', 'classification', 'regression').
`paramlist` | A set of model parameters defined in an R list object.
`innerCore` | The number of cores used for computation.

### Value

The predicted cross validation output.

### Examples

    ## Load data
    methylfile <- system.file('extdata', 'methylData.rds', package='BioMM')
    methylData <- readRDS(methylfile)
    dataY <- methylData[,1]
    ## select a subset of genome-wide methylation data at random
    methylSub <- data.frame(label=dataY, methylData[,c(2:2001)])
    library(ranger)
    library(BiocParallel)
    param1 <- MulticoreParam(workers = 1)
    param2 <- MulticoreParam(workers = 20)
    predY <- predByCV(methylSub, repeats=1, nfolds=10,
                      FSmethod=NULL, cutP=0.1,
                      fdr=NULL, FScore=param1,
                      classifier='randForest',
                      predMode='classification',
                      paramlist=list(ntree=300, nthreads=1),
                      innerCore=param2)
    dataY <- methylData[,1]
    accuracy <- classifiACC(dataY=dataY, predY=predY)
    print(accuracy)

[Package BioMM version 1.4.0 Index]