RcppCNPy-package: File access to data files written by (or for) NumPy (Numeric Python) modules

Description

This package provides access to the cnpy library by Carl Rogers which provides read and write facilities for files created with (or for) the NumPy extension for Python.

Support is provided to reading and writing of either vectors or matrices of numeric or integer types.

Files with gzip compression can be transparently read and written as well.

Usage

npyLoad(filename, type="numeric", dotranspose=TRUE)
  npySave(filename, object, mode="w")
  npyHasIntegerSupport()

Arguments

filename

string with (path and) filename for a npy object file. If the string ends with .gz, compressed files can be read or written.

type

string with type 'numeric' (default) or 'integer'.

object

an R object, currently limited to a vector or matrix of either integer or numeric type

dotranspose

a boolean variable indicating whether a two-dimensional object should be transposed after reading, default is yes

mode

a one-character string indicating whether files are appended to ("a") or written ("w", the default). In case of writing gzip-ed file, this option is not supported as such files can only be (over-)written, and bot appended.

Details

The package uses Rcpp modules to provide R bindings npyLoad() and npySave() which wrap the npy_load() and npy_save() functions. Currently, only one- and two-dimensional vectors and matrices are suppported; higher-dimensional arrays could be added.

Integer support requires access to the long long type which is available if the package is built using the C++11 standard; this is the default since release 0.2.3 which came out after R 3.1.0 permitted used of C++11 in CRAN packages.

References

Rcpp, in particular the Rcpp modules documentation.

The cnpy repository: https://github.com/rogersce/cnpy

Examples

Run this code

# NOT RUN {
    library(RcppCNPy)

    ## load NumPy file with floating-point data
    fmat <- npyLoad("fmat.npy")
    
    ## load NumPy file with integer data
    imat <- npyLoad("imat.npy", "integer")

    ## save floating-point data: matrix and vector
    M <- matrix(0:11, 3, 4, byrow=TRUE) * 1.1
    v <- v <- 0:4 * 1.1
    npySave("fmat.npy", M)
    npySave("fvec.npy", v)

    ## save integer data: matrix and vector
    M <- matrix(0:11, 3, 4, byrow=TRUE)
    v <- v <- 0:4 
    npySave("imat.npy", M)
    npySave("ivec.npy", v)
    
    
# }