readMat {R.matlab} | R Documentation |
Reads a MAT file structure from an input stream, either until End of File
is detected or until maxLength
bytes has been read.
Using maxLength
it is possible to read MAT file structure over
socket connections and other non-terminating input streams. In such cases
the maxLength
has to be communicated before sending the actual
MAT file structure.
Both the MAT version 4 and MAT version 5 file formats are supported. The implementation is based on [1].
From Matlab v7, compressed MAT version 5 files are used
by default [3]. These are not supported.
Use save -V6
in Matlab to write a MAT file compatible with
Matlab v6, that is, to write a non-compressed MAT version 5 file.
## Default S3 method: readMat(con, maxLength=NULL, fixNames=TRUE, verbose=FALSE, ...)
con |
Binary connection to which the MAT file structure should be
written to. A string is interpreted as filename, which then will be
opened (and closed afterwards). |
maxLength |
The maximum number of bytes to be read from the input
stream, which should be equal to the length of the MAT file structure.
If NULL , data will be read until End Of File has been reached. |
fixNames |
If TRUE , names of Matlab variables and fields are
renamed such that they are valid variables names in R. |
verbose |
If TRUE , debug information is written to standard output,
otherwise not. |
... |
Not used. |
For the MAT v5 format, cell structures are read into
R as a list
structure.
Sparse matrices are converted into plain matrices, which means that some matrices will be too large to be allocated.
Returns a named list
structure containing all variables in the
MAT file structure.
Henrik Bengtsson, Mathematical Statistics, Lund University. The internal MAT v4 reader was written by Andy Jacobson at Program in Atmospheric and Oceanic Sciences, Princeton University.
[1] The MathWorks Inc., Matlab - MAT-File Format, version 5, June 1999.
[2] The MathWorks Inc., Matlab - Application Program Interface Guide, version 5, 1998.
[3] The MathWorks Inc., Matlab - MAT-File Format, version 7, October 2004, http://www.mathworks.com/access/helpdesk/help/pdf_doc/matlab/matfile_format.pdf
writeMat
().
path <- system.file("misc", package="R.matlab") for (version in 4:5) { cat("Loading all MAT v", version, " example files in ", path, "...\n", sep="") pattern <- sprintf("-v%d.mat$", version) filenames <- list.files(pattern=pattern, path=path, full.names=TRUE) for (filename in filenames) { cat("Reading MAT file: ", basename(filename), "\n", sep="") mat <- readMat(filename) if (interactive()) { cat("Press ENTER to view data:") readline() } print(mat) } } # Verify that sparse matrices are read the same way in MAT v4 and MAT v5 mat4 <- readMat(file.path(path, "SparseMatrix3-v4.mat")) mat5 <- readMat(file.path(path, "SparseMatrix3-v5.mat")) diff <- sum(abs(mat4$sparseM - mat5$sparseM)) if (diff > .Machine$double.eps) stop("Failed to read identical MAT v4 and MAT v5 sparse matrices.") # Assert that signed and unsigned integer sare read correctly bs <- readMat(file.path(path, "unsignedByte.mat")) if (!identical(as.vector(bs$A), as.double(126:255))) stop("Error reading unsigned bytes saved by Matlab.") is <- readMat(file.path(path, "unsignedInt.mat")) if (!identical(as.vector(is$B), as.double(127:256))) stop("Error reading unsigned ints saved by Matlab.")