Translates a data.frame, in a form usable by MLwiN for multiple membership models,
into a matrix. The data.frame needs to contain (a) columns with membership IDs
(e.g. first row of which might be 2, 3, 5, 6, 0, 0) and (b) columns containing weights
(e.g. first row of which might be 0.25, 0.25, 0.25, 0.25, 0, 0; in this example the first row of
resulting matrix would be 0, 1, 1, 0, 1, 1).
df2matrix(data, idcols, weightcols)An adjacency matrix as returned by sparseMatrix.
A data.frame object.
String vector of the identifier column names.
String vector of the weight column names.
Zhang, Z., Charlton, C.M.J., Parker, R.M.A., Leckie, G., and Browne, W.J. (2016) Centre for Multilevel Modelling, University of Bristol, U.K.
matrix2df