Reference documentation for deal.II version Git 3e8fd02 2017-09-22 11:37:14 +0200
Classes | Public Member Functions | Private Member Functions | Private Attributes | List of all members
MultipleParameterLoop Class Reference

#include <deal.II/base/parameter_handler.h>

Inheritance diagram for MultipleParameterLoop:


class  Entry
class  UserClass

Public Member Functions

 MultipleParameterLoop ()
virtual ~MultipleParameterLoop ()=default
virtual void parse_input (std::istream &input, const std::string &filename="input file", const std::string &last_line="") override
void loop (UserClass &uc)
std::size_t memory_consumption () const
- Public Member Functions inherited from ParameterHandler
 ParameterHandler ()
virtual ~ParameterHandler ()=default
virtual void parse_input (const std::string &filename, const std::string &last_line="")
virtual void parse_input_from_string (const char *s, const std::string &last_line="")
virtual void parse_input_from_xml (std::istream &input)
void clear ()
void declare_entry (const std::string &entry, const std::string &default_value, const Patterns::PatternBase &pattern=Patterns::Anything(), const std::string &documentation=std::string())
void add_action (const std::string &entry, const std::function< void(const std::string &value)> &action)
template<class ParameterType >
void add_parameter (const std::string &entry, ParameterType &parameter, const std::string &documentation=std::string(), const Patterns::PatternBase &pattern=*Patterns::Tools::Convert< ParameterType >::to_pattern())
void declare_alias (const std::string &existing_entry_name, const std::string &alias_name, const bool alias_is_deprecated=false)
void enter_subsection (const std::string &subsection)
void leave_subsection ()
std::string get (const std::string &entry_string) const
long int get_integer (const std::string &entry_string) const
double get_double (const std::string &entry_name) const
bool get_bool (const std::string &entry_name) const
void set (const std::string &entry_name, const std::string &new_value)
void set (const std::string &entry_name, const char *new_value)
void set (const std::string &entry_name, const long int &new_value)
void set (const std::string &entry_name, const double &new_value)
void set (const std::string &entry_name, const bool &new_value)
std::ostream & print_parameters (std::ostream &out, const OutputStyle style) const
void print_parameters_section (std::ostream &out, const OutputStyle style, const unsigned int indent_level, const bool include_top_level_elements=false) 1
void log_parameters (LogStream &out)
void log_parameters_section (LogStream &out)
std::size_t memory_consumption () const
template<class Archive >
void save (Archive &ar, const unsigned int version) const
template<class Archive >
void load (Archive &ar, const unsigned int version)
bool operator== (const ParameterHandler &prm2) const
- Public Member Functions inherited from Subscriptor
 Subscriptor ()
 Subscriptor (const Subscriptor &)
 Subscriptor (Subscriptor &&)
virtual ~Subscriptor ()
Subscriptoroperator= (const Subscriptor &)
Subscriptoroperator= (Subscriptor &&)
void subscribe (const char *identifier=nullptr) const
void unsubscribe (const char *identifier=nullptr) const
unsigned int n_subscriptions () const
void list_subscribers () const
template<class Archive >
void serialize (Archive &ar, const unsigned int version)

Private Member Functions

void init_branches ()
void init_branches_current_section ()
void fill_entry_values (const unsigned int run_no)

Private Attributes

std::vector< Entrymultiple_choices
unsigned int n_branches

Additional Inherited Members

- Public Types inherited from ParameterHandler
enum  OutputStyle {
  Text = 1, LaTeX = 2, Description = 3, XML = 4,
  JSON = 5, ShortText = 193
- Static Public Member Functions inherited from ParameterHandler
static::ExceptionBase & ExcEntryAlreadyExists (std::string arg1)
static::ExceptionBase & ExcValueDoesNotMatchPattern (std::string arg1, std::string arg2)
static::ExceptionBase & ExcAlreadyAtTopLevel ()
static::ExceptionBase & ExcEntryUndeclared (std::string arg1)
static::ExceptionBase & ExcUnbalancedSubsections (std::string arg1, std::string arg2)
static::ExceptionBase & ExcNoSubsection (int arg1, std::string arg2, std::string arg3)
static::ExceptionBase & ExcCannotParseLine (int arg1, std::string arg2, std::string arg3)
static::ExceptionBase & ExcInvalidEntryForPattern (int arg1, std::string arg2, std::string arg3, std::string arg4, std::string arg5)
static::ExceptionBase & ExcInvalidXMLParameterFile ()
static::ExceptionBase & ExcInvalidEntryForPatternXML (std::string arg1, std::string arg2, std::string arg3)
static::ExceptionBase & ExcCannotOpenIncludeStatementFile (int arg1, std::string arg2, std::string arg3)
- Static Public Member Functions inherited from Subscriptor
static::ExceptionBase & ExcInUse (int arg1, char *arg2, std::string &arg3)
static::ExceptionBase & ExcNoSubscriber (char *arg1, char *arg2)

Detailed Description

The class MultipleParameterLoop offers an easy possibility to test several parameter sets during one run of the program. For this it uses the ParameterHandler class to read in data in a standardized form, searches for variant entry values and performs a loop over all combinations of parameters.

Variant entry values are given like this:

*     set Time step size = { 0.1 | 0.2 | 0.3 }

The loop will then perform three runs of the program, one for each value of Time step size, while all other parameters are as specified or with their default value. If there are several variant entry values in the input, a loop is performed for each combination of variant values:

*     set Time step size = { 0.1 | 0.2 }
*     set Solver         = { CG  | GMRES }

will result in four runs of the programs, with time step 0.1 and 0.2 for each of the two solvers.

In addition to variant entries, this class also supports array entries that look like this:

*     set Output file = ofile.{{ 1 | 2 | 3 | 4 }}

This indicates that if there are variant entries producing a total of four different runs, then we will write their results to the files ofile.1, ofile.2, ofile.3 and ofile.4, respectively. Array entries do not generate multiple runs of the main loop themselves, but if there are variant entries, then in the nth run of the main loop, also the nth value of an array is returned.

Since the different variants are constructed in the order of declaration, not in the order in which the variant entries appear in the input file, it may be difficult to guess the mapping between the different variants and the appropriate entry in an array. You will have to check the order of declaration, or use only one variant entry.

It is guaranteed that only selections which match the regular expression (pattern) given upon declaration of an entry are given back to the program. If a variant value does not match the regular expression, the default value is stored and an error is issued. Before the first run of the loop, all possible values are checked for their conformance, so that the error is issued at the very beginning of the program.


The usage of this class is similar to the ParameterHandler class. First the entries and subsections have to be declared, then a loop is performed in which the different parameter sets are set, a new instance of a user class is created which is then called. Taking the classes of the example for the ParameterHandler class, the extended program would look like this:

class HelperClass : public MultipleParameterLoop::UserClass
HelperClass ();
virtual void create_new (const unsigned int run_no);
virtual void run (ParameterHandler &prm);
static void declare_parameters (ParameterHandler &prm);
std::shared_ptr<Problem> p;
HelperClass::HelperClass () : p(0) {}
void HelperClass::create_new (const unsigned int run_no)
p.reset(new Problem());
void HelperClass::declare_parameters (ParameterHandler &prm)
Problem::declare_parameters (prm);
void HelperClass::run (ParameterHandler &prm)
p->get_parameters (prm);
p->do_useful_work ();
int main ()
HelperClass h;
HelperClass::declare_parameters (prm);
prm.parse_input ("prmtest.prm");
prm.loop (h);
return 0;

As can be seen, first a new helper class has to be set up. This must contain a virtual constructor for a problem class. You can also derive your problem class from MultipleParameterLoop::UserClass and let create_new clear all member variables. If you have access to all inherited member variables in some way this is the recommended procedure. A third possibility is to use multiple inheritance and derive a helper class from both the MultipleParameterLoop::UserClass and the problem class. In any case, create_new has to provide a clean problem object which is the problem in the second and third possibility.

The derived class also has to provide for member functions which declare the entries and which run the program. Running the program includes getting the parameters out of the ParameterHandler object.

After defining an object of this helper class and an object of the MultipleParameterLoop class, the entries have to be declared in the same way as for the ParameterHandler class. Then the input has to be read. Finally the loop is called. This executes the following steps:

for (each combination)
UserObject.create_new (run_no);
// set parameters for this run (*this);

UserObject is the parameter to the loop function. create_new is given the number of the run (starting from one) to enable naming output files differently for each run.

Syntax for variant and array entry values

Variant values are specified like prefix{ v1 | v2 | v3 | ... }postfix. Whitespace to the right of the opening brace { is ignored as well as to the left of the closing brace } while whitespace on the respectively other side is not ignored. Whitespace around the mid symbols | is also ignored. The empty selection prefix{ v1 | }postfix is also allowed and produces the strings prefixv1postfix and prefixpostfix.

The syntax for array values is equal, apart from the double braces: prefix{{ v1 | v2 | v3 }}postfix.

Worked example

Given the above extensions to the example program for the ParameterHandler and the following input file

*     set Equation 1 = Poisson
*     set Equation 2 = Navier-Stokes
*     set Output file= results.{{ 1 | 2 | 3 | 4 | 5 | 6 }}
*     subsection Equation 1
*       set Matrix type = Sparse
*       subsection Linear solver
*         set Solver                       = CG
*         set Maximum number of iterations = { 10 | 20 | 30 }
*       end
*     end
*     subsection Equation 2
*       set Matrix type = Full
*       subsection Linear solver
*         set Solver                       = { BiCGStab | GMRES }
*         set Maximum number of iterations = 100
*       end
*     end

this is the output:

*     LinEq: Method=CG, MaxIterations=10
*     LinEq: Method=BiCGStab, MaxIterations=100
*     Problem: outfile=results.1
*              eq1=Poisson, eq2=Navier-Stokes
*              Matrix1=Sparse, Matrix2=Full
*     LinEq: Method=CG, MaxIterations=20
*     LinEq: Method=BiCGStab, MaxIterations=100
*     Problem: outfile=results.2
*              eq1=Poisson, eq2=Navier-Stokes
*              Matrix1=Sparse, Matrix2=Full
*     LinEq: Method=CG, MaxIterations=30
*     LinEq: Method=BiCGStab, MaxIterations=100
*     Problem: outfile=results.3
*              eq1=Poisson, eq2=Navier-Stokes
*              Matrix1=Sparse, Matrix2=Full
*     LinEq: Method=CG, MaxIterations=10
*     LinEq: Method=GMRES, MaxIterations=100
*     Problem: outfile=results.4
*              eq1=Poisson, eq2=Navier-Stokes
*              Matrix1=Sparse, Matrix2=Full
*     LinEq: Method=CG, MaxIterations=20
*     LinEq: Method=GMRES, MaxIterations=100
*     Problem: outfile=results.5
*              eq1=Poisson, eq2=Navier-Stokes
*              Matrix1=Sparse, Matrix2=Full
*     LinEq: Method=CG, MaxIterations=30
*     LinEq: Method=GMRES, MaxIterations=100
*     Problem: outfile=results.6
*              eq1=Poisson, eq2=Navier-Stokes
*              Matrix1=Sparse, Matrix2=Full

Since create_new gets the number of the run it would also be possible to output the number of the run.

Wolfgang Bangerth, October 1997, 2010

Definition at line 1754 of file parameter_handler.h.

Constructor & Destructor Documentation

MultipleParameterLoop::MultipleParameterLoop ( )


Definition at line 2109 of file

virtual MultipleParameterLoop::~MultipleParameterLoop ( )

Destructor. Declare this only to have a virtual destructor, which is safer as we have virtual functions. It actually does nothing spectacular.

Member Function Documentation

void MultipleParameterLoop::parse_input ( std::istream &  input,
const std::string &  filename = "input file",
const std::string &  last_line = "" 

Read input from a stream until the stream returns the eof condition or error. The second argument can be used to denote the name of the file (if that's what the input stream represents) we are reading from; this is only used when creating output for error messages.

If non-empty last_line is provided, the ParameterHandler object will stop parsing lines after encountering last_line . This is handy when adding extra data that shall be parsed manually.

This is the only overload of the three parse_input functions implemented by ParameterHandler overridden with new behavior by this class. This is because the other two parse_input functions just reformat their inputs and then call this version.

Reimplemented from ParameterHandler.

Definition at line 2117 of file

void MultipleParameterLoop::loop ( MultipleParameterLoop::UserClass uc)

run the central loop.

Definition at line 2132 of file

std::size_t MultipleParameterLoop::memory_consumption ( ) const

Determine an estimate for the memory consumption (in bytes) of this object.

Definition at line 2274 of file

void MultipleParameterLoop::init_branches ( )

Initialize the different branches, i.e. construct the combinations.

Definition at line 2145 of file

void MultipleParameterLoop::init_branches_current_section ( )

Traverse the section currently set by enter_subsection()/leave_subsection() and see which of the entries are variant or array entries. Then fill the multiple_choices variable using this information.

Definition at line 2184 of file

void MultipleParameterLoop::fill_entry_values ( const unsigned int  run_no)

Transfer the entry values for one run to the entry tree.

Definition at line 2224 of file

Member Data Documentation

std::vector<Entry> MultipleParameterLoop::multiple_choices

List of variant entry values.

Definition at line 1912 of file parameter_handler.h.

unsigned int MultipleParameterLoop::n_branches

Number of branches constructed from the different combinations of the variants. This obviously equals the number of runs to be performed.

Definition at line 1918 of file parameter_handler.h.

The documentation for this class was generated from the following files: