R: Read an affine matrix from a file

readAffine {RNiftyReg} | R Documentation

## Read an affine matrix from a file

### Description

This function is used to read a 4x4 numeric matrix representing an affine transformation from a file. It is a wrapper around `read.table` which additionally ensures that required attributes are set. The type of the matrix must be specified, as there are differing conventions across software packages.

### Usage

    readAffine(fileName, source = NULL, target = NULL, type = NULL)

### Arguments

`fileName` | A string giving the file name to read the affine matrix from.
`source` | The source image for the transformation. If `NULL`, the file will be searched for a comment specifying the path to a NIfTI file.
`target` | The target image for the transformation. If `NULL`, the file will be searched for a comment specifying the path to a NIfTI file.
`type` | The type of the affine matrix, which describes what convention is it is stored with. Currently valid values are `"niftyreg"` and `"fsl"` (for FSL FLIRT). If `NULL`, the function will look in the file for a comment specifying the type.

### Value

An matrix with class `"affine"`, converted to the NiftyReg convention and with `source` and `target` attributes set appropriately.

### Author(s)

Jon Clayden <code@clayden.org>

### See Also

`read.table`, `writeAffine`

### Examples

    print(readAffine(system.file("extdata","affine.txt",package="RNiftyReg")))

[Package RNiftyReg version 2.6.5 Index]