Data parsing

Routines for reading simple column data into LookupTable1D are available. This is typically used, e.g., when parsing transport coefficients or other types of data required by a computer simulation.

Tip

The DataParser C++ API is found at https://chombo-discharge.github.io/chombo-discharge/doxygen/html/namespaceDataParser.html.

Currently, three types of file reads are supported:

1. Read column data, where the user can specify the columns that are parsed into a lookup table.

   These files can be arranged in the form

   0.0 1.0
   1.0 2.0
   2.0 3.0
   

   It is also possible to restrict which rows are read, by specifying string identifiers on the line preceding the data and on the line immediately after the data.

   Important

   After parsing into a LookupTable1D, the user must regularize the table in order to use the interpolation functions. See Regularize table.

2. Read particle data, where the particle data is in a \((x,y,z,w)\) file format, where \(w\) is the particle weight.

   The function signatures for reading this type of data are:

   /**
    * @brief Simple file parser which will read particles (position/weight) from an ASCII file.
    * @details Particles should be arranged as rows, e.g. in the form
    * x   y   z   w
    * 0.0 0.0 0.0 1
    * @param[in] a_fileName    Input file name. Must be an ASCII file organized into rows and columns.
    * @param[in] a_xColumn     Column containing the x-coordinate
    * @param[in] a_yColumn     Column containing the y-coordinate
    * @param[in] a_zColumn     Column containing the z-coordinate
    * @param[in] a_wColumn     Column containing the particle weight
    * @param[in] a_ignoreChars Characters indicating comments in the file. Lines starting with these characters are
    * ignored.
    * @return Return value
    */
   ParticleSoA<NoPayload>
   readPointParticlesASCII(const std::string&       a_fileName,
                           const unsigned int       a_xColumn     = 0,
                           const unsigned int       a_yColumn     = 1,
                           const unsigned int       a_zColumn     = 2,
                           const unsigned int       a_wColumn     = 3,
                           const std::vector<char>& a_ignoreChars = {'#', '/'});
   

3. Read triangle mesh data from PLY or VTK files, returning a list of Triangle objects with per-vertex scalar metadata. The file type is inferred from the extension (.ply/.PLY or .vtk/.VTK). A named per-vertex scalar property (e.g., a PLY vertex property or VTK point-data scalar) is read as the vertex metadata; if the identifier is not found, a warning is issued and metadata defaults to zero. Non-triangular facets are skipped with a warning.

   The function signature is:

   /**
    * @brief Read a PLY or VTK triangle mesh file and return a list of Triangle objects.
    * @details Reads vertex positions and face connectivity from the file. If a_vertexDataIdentifier
    * matches a named per-vertex scalar property in the file (a PLY vertex property or a VTK
    * point-data scalar), that data is stored as the vertex metadata on each Triangle via
    * setVertexData(). If the identifier is not found, a warning is issued and all vertex data
    * values are set to zero.
    *
    * Non-triangular facets are skipped with a warning. The file type is inferred from the
    * extension (.ply / .PLY or .vtk / .VTK); any other extension results in a fatal error.
    *
    * @param[in] a_filename             Path to the input mesh file.
    * @param[in] a_vertexDataIdentifier Name of the per-vertex scalar property to read as
    *                                   Triangle vertex metadata.
    * @return Vector of fully initialised Triangle objects, sorted in file order.
    */
   std::vector<std::shared_ptr<Triangle>>
   readTriangles(const std::string& a_filename, const std::string& a_vertexDataIdentifier);
   

   Note

   Triangle objects are returned in file order. To perform efficient spatial queries (e.g., finding the closest triangle to a point), pass the result to a TriangleCollection.