simulateGenotypeMatrix {GWASTools} | R Documentation

## Simulate Genotype or Intensity Matrix & Load into GDS/NetCDF File

### Description

These functions create a simulated genotype or intensity file for test and examples.

### Usage

    simulateGenotypeMatrix(n.snps=10, n.chromosomes=10,
                           n.samples=1000, filename,
                           file.type=c("gds", "ncdf"), silent=TRUE)

### Arguments

`n.snps` | An integer corresponding to the number of SNPs per chromosome, the default value is 10. For this function, the number of SNPs is assumed to be the same for every chromosome.
`n.chromosomes` | An integer value describing the total number of chromosomes with default value 10.
`n.samples` | An integer representing the number of samples for our data. The default value is 1000 samples.
`filename` | A string that will be used as the name of the file. This is to be used later when opening and retrieving data generated from this function.
`file.type` | The type of file to create ("gds" or "ncdf")
`silent` | Logical value. If `FALSE`, the function returns a table of genotype counts generated. The default is `TRUE`; no data will be returned in this case.

### Details

The resulting netCDF file will have the following characteristics:

Dimensions:

'snp': n.snps*n.chromosomes length

'sample': n.samples length

Variables:

'sampleID': sample dimension, values 1-n.samples

'position': snp dimension, values [1,2,...,n.chromosomes] n.snps times

'chromosome': snp dimension, values [1,1,...]n.snps times, [2,2,...]n.snps times, ..., [n.chromosomes,n.chromosomes,...]n.snps times

'genotype': 2-dimensional snp x sample, values 0, 1, 2 chosen from allele frequencies that were generated from a uniform distribution on (0,1). The missing rate is 0.05 (constant across all SNPs) and is denoted by -1.

OR

'quality': 2-dimensional snp x sample, values between 0 and 1 chosen randomly from a uniform distribution. There is one quality value per snp, so this value is constant across all samples.

'X': 2-dimensional snp x sample, value of X intensity taken from a normal distribution. The mean of the distribution for each SNP is based upon the sample genotype. Mean is 0,2 if sample is homozygous, 1 if heterozygous.

'Y': 2-dimensional snp x sample, value of Y intensity also chosen from a normal distribution, where the mean is chosen according to the mean of X so that sum of means = 2.

### Value

`simulateGenotypeMatrix` returns a table of genotype calls if the silent variable is set to `FALSE`, where 2 indicates an AA genotype, 1 is AB, 0 is BB and -1 corresponds to a missing genotype call.

`simulateIntensityMatrix` returns a list if the silent variable is set to FALSE, which includes:

`het` | Heterozygosity table
`nmiss` | Number of missing values

A file is created and written to disk.

### Author(s)

Caitlin McHugh

### See Also

`GdsGenotypeReader`, `GdsIntensityReader`, `NcdfGenotypeReader`, `NcdfIntensityReader`

### Examples

    filenm <- tempfile()

    simulateGenotypeMatrix(filename=filenm )

    file <- GdsGenotypeReader(filenm)
    file #notice the dimensions and variables listed

    genot <- getGenotype(file)
    table(genot) #can see the number of missing calls

    chrom <- getChromosome(file)
    unique(chrom) #there are indeed 10 chromosomes, as specified in the function call

    close(file)

    simulateIntensityMatrix(filename=filenm, silent=FALSE )

    file <- GdsIntensityReader(filenm)
    file #notice the dimensions and variables listed

    xint <- getX(file)
    yint <- getY(file)
    print("Number missing is: "); sum(is.na(xint))

    chrom <- getChromosome(file)
    unique(chrom) #there are indeed 10 chromosomes, as specified in the function call

    close(file)

    unlink(filenm)

[Package GWASTools version 1.33.3 Index]