BMIQ: BMIQ

Description Usage Arguments Details Value Author(s)

View source: R/bmiq.R

Description

This function makes 3 indipendent attempts to fit a 3-state beta mixture model on the provided type I probes. An attempt is successful if at least 4 probes are assigned to each level. In case all attempts fail, the return value is NULL.

Usage

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BMIQ(
  beta.v,
  design.v,
  doH = TRUE,
  nfit = 50000,
  th1.v = c(0.2, 0.75),
  th2.v = NULL,
  niter = 5,
  tol = 0.001
)

Arguments

beta.v

double vector consisting of beta values. Missing values (NAs) cannot be handled, so these must be removed or imputed prior to running BMIQ. Before normalization, beta values that are exactly 0 and exactly 1 are replaced by the minimum positive and maximum value below 1, respectively.

design.v

integer vector of length length(beta.v), containing the values 1 and 2 only. These values specify probe design type.

doH

Flag indicating if normalization for hemimethylated type II probes is to be performed.

nfit

Number of probes of a given design to use for the fitting. Smaller values will make BMIQ faster at the expense of accuracy. Values between 10000 and 50000 seem to work well.

th1.v

Thresholds "type 1" to use for the initialization of the EM algorithm. These values should represent best guesses for calling type I probes hemi-methylated and methylated, and are refined in further steps by the algorithm.

th2.v

Thresholds "type 2" to used for the initialization of the EM algorithm. These values should represent best guesses for calling type II probes hemi-methylated and methylated, and are refined in further steps by the EM algorithm. If this is NULL (default), the thresholds are estimated based on th1.v and a modified PBC correction method.

niter

Maximum number of EM iterations to be performed.

tol

Tolerance threshold for EM algorithm.

Details

Performs Beta-mixture quantile normalization, adjusting for type II bias in Infinium 450K data.

Value

List with the following elements:

"all"

The normalised beta-profile for the sample.

"class1"

Methylation state assigned to the type I probes.

"class2"

Methylation state assigned to the type II probes.

"av1"

Mean beta values for the nL classes for type I probes.

"av2"

Mean beta values for the nL classes for type II probes.

"hf"

Hubble dilation factor.

"th1"

Estimated thresholds used for type I probes.

"th2"

Estimated thresholds used for type II probes.

Author(s)

Andrew Teschendorff and Steve Horvath; with minor modifications by Yassen Assenov


RnBeads documentation built on March 3, 2021, 2 a.m.