The matio-library aims to facilitate the reading and writing of matrix files in transport models, in a way that allows to easily switch between matrix formats. The abstract base classes TMatrixReader/TMatrixWriter are the ancestor classes for the format specific readers/writers. They are intended to read/write matrix files that may contain multiple matrices. The TMatrixReader.Read/TMatrixWriter.Write methods read/write a single row of each matrix in the matrix file. This allows to apply a transport model zone by zone for the successive model zones, without having to store the complete matrices in memory.
Matrices are identified either by label, or by their index in the matrix file. Depending on the file format, label-based access (e.g. text format without header), or index-based access (e.g. the omx-format) may not be supported.
To read a selection of matrices, specified by their label, a list of labels for the matrices to be read must be supplied. Matrices can then be accessed by their list index.
The MatrixReader and MatrixWriter-objects can be instantiated by providing a key-value string specifying the desired format and other (format specific) properties, for example:
var Reader := MatrixFormats.CreateReader('file=matrix.dat; format=txt; delim=comma');
will create a MatrixReader-object that reads matrices from a comma-separated text file named 'matrix.dat'.
var Reader := MatrixFormats.CreateReader('file=los.omx; format=omx',['IVT','WaitTime']);
will create a MatrixReader-object that reads the matrices with labels IVT and WaitTime from an open matrix file named 'los.omx'.
The following formats are supported by the matio-library:
- Text format (various encodings and separators)
- The binary Minutp-format that can be used within Citilab's CUBE
- The binary PTV Visum format
- Open Matrix Format (omx)
- The binary 4G-format that is being used within the national transport models of Flanders and the Netherlands.
Support for other formats can be added by registering the format at the global MatrixFormats-object.
Before you can compile this library, you will need to clone the https://github.com/transportmodelling/Utils repository, and then add it to your Delphi Library path.