scaleData {msImpute} | R Documentation

## Standardize a matrix to have optionally row means zero and variances one, and/or column means zero and variances one.

### Description

Standardize a matrix to have optionally row means zero and variances one, and/or column means zero and variances one.

### Usage

    scaleData(
      object,
      maxit = 20,
      thresh = 1e-09,
      row.center = TRUE,
      row.scale = TRUE,
      col.center = TRUE,
      col.scale = TRUE,
      trace = FALSE
    )

### Arguments

`object` | numeric matrix giving log-intensity where missing values are denoted by NA. Rows are peptides, columns are samples.
`maxit` | numeric. maximum iteration for the algorithm to converge (default to 20). When both row and column centering/scaling is requested, iteration may be necessary.
`thresh` | numeric. Convergence threshold (default to 1e-09).
`row.center` | logical. if row.center==TRUE (the default), row centering will be performed resulting in a matrix with row means zero. If row.center is a vector, it will be used to center the rows. If row.center=FALSE nothing is done.
`row.scale` | if row.scale==TRUE, the rows are scaled (after possibly centering, to have variance one. Alternatively, if a positive vector is supplied, it is used for row centering.
`col.center` | Similar to row.center
`col.scale` | Similar to row.scale
`trace` | logical. With trace=TRUE, convergence progress is reported, when iteration is needed.

### Details

Standardizes rows and/or columns of a matrix with missing values, according to the `biScale` algorithm in Hastie et al. 2015. Data is assumed to be normalised and log-transformed. Please note that data scaling might not be appropriate for MS1 data. A good strategy is to compare mean-variance plot (`plotCV2`) before and after imputation. If the plots look differently, you may need to skip data scaling. The MS1 data are more variable (tend to have higher CV^2), and may contain outliers which will skew the scaling.

### Value

A list of two components: E and E.scaled. E contains the input matrix, E.scaled contains the scaled data

### References

Hastie, T., Mazumder, R., Lee, J. D., & Zadeh, R. (2015). Matrix completion and low-rank SVD via fast alternating least squares. The Journal of Machine Learning Research, 16(1), 3367-3402.

Hediyeh-zadeh, S., Webb, A. I., & Davis, M. J. (2020). MSImpute: Imputation of label-free mass spectrometry peptides by low-rank approximation. bioRxiv.

### See Also

selectFeatures, msImpute

### Examples

    data(pxd010943)
    y <- pxd010943
    y <- log2(y)
    keep <- (rowSums(!is.na(y)) >= 4)
    y <- as.matrix.data.frame(y[keep,])
    y <- scaleData(y, maxit=30)

[Package msImpute version 1.4.0 Index]