queryGeNetClassifier {geNetClassifier} | R Documentation

## Queries the classifier trained with geNetClassifier.

### Description

Queries the classifier trained by geNetClassifier in order to find out the class of new samples.

### Usage

    queryGeNetClassifier(classifier, eset, minProbAssignCoeff = 1,
        minDiffAssignCoeff = 0.8, verbose = TRUE)

### Arguments

`classifier` | Classifier returned by geNetClassifier. (@classifier)
`eset` | ExpressionSet or Matrix. Gene expression matrix of the new samples.
`minProbAssignCoeff` | Numeric. Coefficient to modify the minimum probability requird to assign a sample to a class. Reduce to improve call rate. Increase to reduce error. 0: Removes this restriction. The sample will always be assigned to the class with the highest probability. between 0 and 1: Reduces the required probability to assign a sample to a class. >1: Increases the required probability. Warning: if `minProbCoef` is equal to `2*number of classes`, all the samples will be left as 'NotAssigned'.
`minDiffAssignCoeff` | Numeric. Coefficient to modify the required difference between the two most likelly classes. Reduce to improve call rate. Increase to reduce error. 0: Removes this restriction. The probability of the second most-likely class will not be taken into account. between 1 and 1: Reduces the required difference to assign the sample. >1: Increases the required difference. Warning: if `minDiffAssignCoeff` is equal to the number of classes, all the samples will be left as 'NotAssigned'.
`verbose` | Logical. If TRUE, messages indicating the execution progress will be printed on screen.

### Details

By default, in order to assign a sample two contitions must be met:

- if `minProbAssignCoeff = 1`The probability of belonging to the class should be at least double of the random probability.

- if `minDiffAssignCoeff = 0.8`The difference of probabilities between the most likely class and the second most likely class should be more than 80 This means, that in a 4-class classifier, in order to assing a sample, the highest probabiity should be at least 0.5 (2x0.25), and the next most-likely-class should have a probability at least 0.2 (80 If these conditions are not met, the sample will be left as `notAssigned`.
  Modify the arguments values in order to modify these assignment conditions. Setting `minProbAssignCoeff = 0` and `minDiffAssignCoeff = 0` all samples will be assigned to the most likely class without any further restrictions.

### Value

List:

- call Command used to execute the function.

- classes Classes to wich each of the samples were asigned to.

- probabilities Probabilities to the 2 classes each sample is most likelly to belong to.

### Author(s)

Bioinformatics and Functional Genomics Group. Centro de Investigacion del Cancer (CIC-IBMCC, USAL-CSIC). Salamanca. Spain

### See Also

Main package function and classifier training: `geNetClassifier`
Query summary: `querySummary`
External validation stats: `externalValidation.stats` and `externalValidation.probMatrix`

### Examples

    ##########################
    ## Classifier training
    ##########################

    # Load an expressionSet:
    library(leukemiasEset)
    data(leukemiasEset)

    # Select the train samples:
    # There should be the same number of samples from each class.
    trainSamples<- c(1:10, 13:22, 25:34, 37:46, 49:58)
    # summary(leukemiasEset$LeukemiaType[trainSamples])

    # Train a classifier or load a trained one:
    # leukemiasClassifier <- geNetClassifier(leukemiasEset[,trainSamples],
    #    sampleLabels="LeukemiaType", plotsName="leukemiasClassifier")
    data(leukemiasClassifier) # Sample trained classifier

    ##########################
    ## Classifier Query
    ##########################
    # Select the samples to query the classifier
    #   - Real use: samples whose class we want to known
    querySamples <- "GSM330154.CEL"
    #   - External validation: samples not used for training
    querySamples <- c(1:60)[-trainSamples]

    #### Make a query to the classifier ("ask" about what class the new samples are):
    queryResult <- queryGeNetClassifier(leukemiasClassifier, leukemiasEset[,querySamples])

    # See the class it assigned to each sample:
    queryResult$class[1:5]
    # Or the samples which it wasn't sure about:
    t(queryResult$probabilities[,queryResult$class=="NotAssigned"])

    # Obtain an overview of the results
    querySummary(queryResult)

    #### Optional: Modify assignment conditions
    # (minDiffCoef=0, minProbCoef=0: All samples will be assigned to the most likely class)
    queryResult_AssignAll <- queryGeNetClassifier(leukemiasClassifier,
        leukemiasEset[,querySamples], minDiffAssignCoeff=0, minProbAssignCoeff=0)
    # No samples are left as "NotAssigned":
    queryResult$probabilities[,queryResult_AssignAll$class=="NotAssigned"]

    #### External validation:
    # Confusion matrix:
    confMatrix <- table(leukemiasEset[,querySamples]$LeukemiaType,
        queryResult_AssignAll$class)
    # New accuracy, call rate, sensitivity and specificity:
    externalValidation.stats(confMatrix)
    # Probability matrix for the assigned samples
    externalValidation.probMatrix(queryResult, leukemiasEset[,querySamples]$LeukemiaType)

[Package geNetClassifier version 1.27.9 Index]