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Last edited by Timo Koch
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Custom input data

If you want to read custom user data, let's say to read a couple of check point for your time loop from file, here is some recipes of how to achieve that with simple helpers available in DuMux.

Read an array of numbers

If you have a simple text file containing a list of numbers

0.1
0.2
0.3
0.4

You can read these numbers into a std::vector<double> like this

#include <dumux/io/container.hh>

const auto numbers = Dumux::readFileToContainer<std::vector<double>>("numbers.txt");

The file extension is arbitrary. The container type std::vector<> needs to support begin(), end(), and push_back(). It has to have an alias value_type (the type of the element, here double) and this type needs to have an overloaded operator>> to be constructible from an input stream. With similar code you can also multi-column data like this


0.1 0.2 0.3
0.1 0.4 0.5

for example into a std::vector<Dune::FieldVector<float, 3>>

#include <dune/common/fvector.hh>
#include <dumux/io/container.hh>

const auto coords = Dumux::readFileToContainer<std::vector<Dune::FieldVector<double, 3>>>("coords.txt");

Read INI-style config data

You can read config data (key-value data) using the Dune::ParameterTreeParser. This is the same type of file we use for DuMux input files. Given a config file like this

[MyData]
InjectionRate = 0.1 0.2 0.3 0.4
BoundaryFlags = 3 4 5 6

[Problem]
EnableGravity = false

the data can be read into a Dune::ParameterTree like this

#include <dune/common/parametertreeparser.hh>

Dune::ParameterTree config;
Dune::ParameterTreeParser::readINITree("config.ini", config);

Again, the file extension is arbitrary. You can retrieve data by casting it into another type like this

const bool enableGravity = config.get<bool>("Problem.EnableGravity");
const auto boundaryFlags = config.get<std::vector<int>>("MyData.BoundaryFlags");

Read XML-formatted config data

XML (Extensible Markup Language) is a very flexible structured data format. You can read and write XML files using the TinyXML-2 library contained in DuMux. For example, given an XML file like this

<?xml version="1.0"?>
<!-- Simple custom data file -->
<InputData>
  <!-- Injection rates are in kg/s -->
  <InjectionRates>
  0.1 0.2 0.3 0.4
  </InjectionRates>

  <!-- BoundaryTypes: -1: no boundary, 0: Dirichlet, 1: Noflow, 2: Infiltration, 3: Outflow -->
  <BoundaryTypes>
  0 -1 -1 2
  </BoundaryTypes>
</InputData>

You can initialise the file reader like this

#include <dumux/io/xml/tinyxml2.h>

tinyxml2::XMLDocument xmlData;
const auto returnCode = xmlData.LoadFile("mydata.xml"); // extension arbitrary
if (returnCode != tinyxml2::XML_SUCCESS)
    DUNE_THROW(Dune::IOError, "Couldn't open XML file.");

and read fields like this

const tinyxml2::XMLElement* inputData = xmlData.FirstChildElement("InputData");
std::stringstream injectionData(inputData->FirstChildElement("InjectionRates")->GetText());
const auto injectionRates = readStreamToContainer<std::vector<double>>(injectionData);