3 <title>The Settings Scheme</title>
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30 <h2>The Settings Scheme</h2>
32 The <code>Settings</code> class keeps track of all the flags, modes,
33 parameters and words used during the event generation. As such, it
34 serves all the <code>Pythia</code> program elements from one central
35 repository. Accessing it allows the user to modify the generator
39 Each <code>Pythia</code> object has a public member <code>settings</code>
40 of the <code>Settings</code> class. Therefore you access the
41 settings methods as <code>pythia.settings.command(argument)</code>,
42 assuming that <code>pythia</code> is an instance of the <code>Pythia</code>
43 class. Further, for the most frequent user tasks, <code>Pythia</code>
44 methods have been defined, so that <code>pythia.command(argument)</code>
45 would work, see further below.
48 The central section on this page is the Operation one. The preceding
49 concepts section is there mainly to introduce the basic structure and
50 the set of properties that can be accessed. The subsequent sections
51 provide a complete listing of the existing public methods, which most
52 users probably will have little interaction with.
56 We distinguish four kinds of user-modifiable variables, by the way
57 they have to be stored:
59 <li>Flags are on/off switches, and are stored as <code>bool</code>.</li>
60 <li>Modes corresponds to a finite enumeration of separate options,
61 and are stored as <code>int</code>.</li>
62 <li>Parameters take a continuum of values, and are stored as
63 <code>double</code>. The shorthand notation parm is used in the C++
64 code and XML tags, so that all four kinds are represented by
65 four-letter type names.</li>
66 <li>Words are simple character strings and are stored as
67 <code>string</code>. No blanks or double quotation marks (") may
68 appear inside a word, the former to simplify parsing of an input file
69 and the latter not to cause conflicts with XML attribute delimiters.
70 Currently the main application is to store file names.</li>
74 In general, each variable stored in <code>Settings</code> is associated
75 with four kinds of information:
77 <li>The variable name, of the form <code>class:name</code>
78 (or <code>file:name</code>, usually these agree), e.g.
79 <code>TimeShower:pTmin</code>. The class/file part usually identifies
80 the <code>.xml</code> file where the variable is defined, and the part of
81 the program where it is used, but such a connection cannot be strictly
82 upheld, since e.g. the same variable may be used in a few different
83 cases (even if most of them are not).</li>
84 <li>The default value, set in the original declaration, and intended
85 to represent a reasonable choice.</li>
86 <li>The current value, which differs from the default when the user so
88 <li>An allowed range of values, represented by meaningful
89 minimum and maximum values. This has no sense for a <code>flag</code>
90 or a <code>word</code> (and is not used there), is usually rather
91 well-defined for a <code>mode</code>, but less so for a <code>parm</code>.
92 Often the allowed range exaggerates the degree of our current knowledge,
93 so as not to restrict too much what the user can do. One may choose
94 not to set the lower or upper limit, in which case the range is
99 Technically, the <code>Settings</code> class is implemented with the
100 help of four separate maps, one for each kind of variable, with the
101 variable <code>name</code> used as key.
105 The normal flow of setting values is:
110 When a <code>Pythia</code> object <code>pythia </code>is created,
111 the member <code>pythia.settings</code> is asked to scan the files
112 listed in the <code>Index.xml</code> file in the <code>xmldoc</code>
116 In all of the files scanned, lines beginning with
117 <code><flag</code>, <code><mode</code>, <code><parm</code>
118 or <code><word</code> are identified, and the information on
119 such a line is used to define a new flag, mode, parameter or word.
120 To exemplify, consider a line
122 <parm name="TimeShower:pTmin" default="0.5" min="0.1" max="2.0">
124 which appears in the <code>TimeShower.xml</code> file, and there
125 defines a parameter <code>TimeShower:pTmin</code> with default value
126 0.5 GeV and allowed variation in the range 0.1 - 2.0 GeV. The min
127 and max values are optional.
128 <br/><b>Important:</b> the values in the <code>.xml</code> files should
129 not be changed, except by the PYTHIA authors. Any changes should be
130 done with the help of the methods described below.
134 Between the creation of the <code>Pythia</code> object and the
135 <code>init</code> call for it, you may use several alternative
136 methods to modify some of the default values. The same variable
137 can be changed several times. If so, it is the last read value
138 that counts. The two special
139 <code><?php $filepath = $_GET["filepath"];
140 echo "<a href='Tunes.php?filepath=".$filepath."' target='page'>";?>Tune:ee</a></code> and
141 <code><?php $filepath = $_GET["filepath"];
142 echo "<a href='Tunes.php?filepath=".$filepath."' target='page'>";?>Tune:pp</a></code>
143 modes are expanded to change several settings in one go, but these obey
144 the same ordering rules.
147 a) Inside your main program you can directly set values with
149 pythia.readString(string)
151 where both the variable name and the value are contained inside
152 the character string, separated by blanks and/or a =, e.g.
154 pythia.readString("TimeShower:pTmin = 1.0");
156 The match of the name to the database is case-insensitive. Names
157 that do not match an existing variable are ignored. A warning is
158 printed, however. Strings beginning with a non-alphanumeric character,
159 like # or !, are assumed to be comments and are not processed at all.
160 Values below the minimum or above the maximum are set at
161 the respective border. For <code>bool</code> values, the following
162 notation may be used interchangeably:
163 <code>true = on = yes = ok = 1</code>, while everything else gives
164 <code>false</code> (including but not limited to
165 <code>false</code>, <code>off</code>, <code>no</code> and 0).<br/>
168 b) The <code>Pythia</code> <code>readString(string)</code> method
169 actually does not do changes itself, but sends on the string either
170 to the <code>Settings</code> class or to <code>ParticleData</code>.
171 The former holds if the string begins with a letter, the latter
172 if it begins with a digit. If desired, it is possible to communicate
173 directly with the corresponding <code>Settings</code> method:
175 pythia.settings.readString("TimeShower:pTmin = 1.0");
177 In this case, changes intended for <code>ParticleData</code>
178 would not be understood.
181 c) Underlying the <code>settings.readString(string)</code> method are
182 the settings-type-sensitive commands in the <code>Settings</code>, that
183 are split by names containing <code>flag</code>, <code>mode</code>,
184 <code>parm</code> or <code>word</code>. Thus, the example now reads
186 pythia.settings.parm("TimeShower:pTmin", 1.0);
188 Such a form could be convenient e.g. if a parameter is calculated
189 at the beginning of the main program, and thus is available as a
190 variable rather than as a character string.
191 Note that Boolean values must here be given as <code>true</code> or
192 <code>false</code> i.e. there is less flexibility than with the
196 At the same level, there are several different methods available.
197 These are included in the full description below, but normally the user
198 should have no need for them.
201 d) A simpler and more useful way is to collect all your changes
202 in a separate file, with one line per change, e.g.
204 TimeShower:pTmin = 1.0
206 Each line is read in as a string and processed with the methods already
209 The file can be read by the
211 pythia.readFile(fileName);
213 method (or an <code>istream</code> instead of a <code>fileName</code>).
214 The file can freely mix commands to the <code>Settings</code> and
215 <code>ParticleData</code> classes, and so is preferable. Lines with
216 settings are handled by calls to the
217 <code>pythia.settings.readString(string)</code> method.
221 In the <code>pythia.init(...)</code> call, many of the various other program
222 elements are initialized, making use of the current values in the database.
223 Once initialized, the common <code>Settings</code> database is likely not
224 consulted again by these routines. It is therefore not productive to do
225 further changes in mid-run: at best nothing changes, at worst you may
226 set up inconsistencies.
229 A routine <code>reInit(fileName)</code> is provided, and can be used to
230 zero all the maps and reinitialize them from scratch. Such a call might be
231 useful if several subruns are to be made with widely different parameter
232 sets - normally the maps are only built from scratch once, namely when the
233 <code>Pythia()</code> object is created. A more economical alternative is
234 offered by <code>resetAll()</code>, however, which sets all variables back
235 to their default values.
239 You may at any time obtain a listing of all variables in the
242 pythia.settings.listAll();
244 The listing is strictly alphabetical, which at least means that names
245 from the same file are kept together, but otherwise may not be so
246 well-structured: important and unimportant ones will appear mixed.
247 A more relevant alternative is
249 pythia.settings.listChanged();
251 where you will only get those variables that differ from their
252 defaults. Or you can use
254 pythia.settings.list("string");
256 where only those variables with names that contain the string
257 (case-insensitive match) are listed. Thus, with a string
258 <code>shower</code>, the shower-related variables would be shown.
262 The above listings are in a tabular form that cannot be read
263 back in. Assuming you want to save all changed settings (maybe because
264 you read in changes from several files), you can do that by calling
266 pythia.settings.writeFile(fileName);
268 This file could then directly be read in by
269 <code>readFile(fileName)</code> in a subsequent (identical) run.
270 Some variants of this command are listed below.
276 The complete list of methods and arguments is as follows. Most of the
277 ones of interest to the user have already been mentioned above.
278 Others can be used, but the same functionality is better achieved
279 by higher-level routines. Some are part of the internal machinery,
280 and should not be touched by user.
283 Note that there is no <code>Settings::readFile(...)</code> method.
284 The intention is that you should use <code>Pythia::readFile(...)</code>.
285 It parses and decides which individual lines should be sent on to
286 <code>Settings::readString(...)</code>.
288 <a name="method1"></a>
289 <p/><strong>Settings::Settings() </strong> <br/>
290 the constructor, which takes no arguments. Internal.
293 <a name="method2"></a>
294 <p/><strong>bool Settings::initPtr(Info* infoPtrIn) </strong> <br/>
295 initialize pointer to error-message database. Internal.
298 <a name="method3"></a>
299 <p/><strong>bool Settings::init(string startFile = "../xmldoc/Index.xml", bool append = false, ostream& os = cout) </strong> <br/>
300 read in the settings database.
301 <br/><code>argument</code><strong> startFile </strong> (<code>default = <strong>"../xmldoc/Index.xml"</strong></code>) :
302 read in the settings from all the files listed in this file, and
303 assumed to be located in the same subdirectory.
305 <br/><code>argument</code><strong> append </strong> (<code>default = <strong>false</strong></code>) :
306 By default nothing is done if the method has already been called once.
307 If true the further settings read in are added to the current database.
309 <br/><code>argument</code><strong> os </strong> (<code>default = <strong>cout</strong></code>) :
310 stream for error printout.
312 <br/><b>Note:</b> The method returns false if it fails.
315 <a name="method4"></a>
316 <p/><strong>bool Settings::reInit(string startFile = "../xmldoc/Index.xml", ostream& os = cout) </strong> <br/>
317 overwrite the existing database.
318 <br/><code>argument</code><strong> startFile </strong> (<code>default = <strong>"../xmldoc/Index.xml"</strong></code>) :
319 read in the settings from all the files listed in this file, and
320 assumed to be located in the same subdirectory.
322 <br/><code>argument</code><strong> os </strong> (<code>default = <strong>cout</strong></code>) :
323 stream for error printout.
325 <br/><b>Note:</b> The method returns false if it fails.
328 <a name="method5"></a>
329 <p/><strong>bool Settings::readString(string line, bool warn = true, ostream& os = cout) </strong> <br/>
330 read in a string, and change the relevant quantity in the database.
331 It is normally used indirectly, via
332 <code>Pythia::readString(...)</code> and
333 <code>Pythia::readFile(...)</code>.
334 <br/><code>argument</code><strong> line </strong> :
335 the string to be interpreted as an instruction.
337 <br/><code>argument</code><strong> warn </strong> (<code>default = <strong>true</strong></code>) :
338 write a warning message or not whenever the instruction does not make
339 sense, e.g. if the variable does not exist in the databases.
341 <br/><code>argument</code><strong> os </strong> (<code>default = <strong>cout</strong></code>) :
342 stream for error printout.
344 <br/><b>Note:</b> the method returns false if it fails to
345 make sense out of the input string.
348 <a name="method6"></a>
349 <p/><strong>bool Settings::writeFile(string toFile, bool writeAll = false) </strong> <br/>
351 <strong>bool Settings::writeFile(ostream& os = cout, bool writeAll = false) </strong> <br/>
352 write current settings to a file or to an <code>ostream</code>.
353 <br/><code>argument</code><strong> toFile, os </strong> :
354 file or stream on which settings are written.
356 <br/><code>argument</code><strong> writeAll </strong> (<code>default = <strong>false</strong></code>) :
357 normally only settings that have been changed are written,
358 but if true then all settings are output.
360 <br/><b>Note:</b> the method returns false if it fails.
363 <a name="method7"></a>
364 <p/><strong>void Settings::listAll(ostream& os = cout) </strong> <br/>
366 <strong>void Settings::listChanged(ostream& os = cout) </strong> <br/>
368 <strong>void Settings::list(string match, ostream& os = cout) </strong> <br/>
369 list all or changed settings, or a group of them.
370 <br/><code>argument</code><strong> match </strong> :
371 list all those settings where the name contains
372 the <code>match</code> (sub)string (case-insensitive).
374 <br/><code>argument</code><strong> os </strong> (<code>default = <strong>cout</strong></code>) :
375 output stream for the listing.
379 <a name="method8"></a>
380 <p/><strong>void Settings::resetAll() </strong> <br/>
381 reset all current values to their defaults.
384 <a name="method9"></a>
385 <p/><strong>bool Settings::isFlag(string key) </strong> <br/>
387 <strong>bool Settings::isMode(string key) </strong> <br/>
389 <strong>bool Settings::isParm(string key) </strong> <br/>
391 <strong>bool Settings::isWord(string key) </strong> <br/>
392 return true if an entry of the given name and kind
396 <a name="method10"></a>
397 <p/><strong>void Settings::addFlag(string key, bool default) </strong> <br/>
399 <strong>void Settings::addMode(string key, int default, bool hasMin, bool hasMax, int min, int max) </strong> <br/>
401 <strong>void Settings::addParm(string key, double default, bool hasMin, bool hasMax, double min, double max) </strong> <br/>
403 <strong>void Settings::addWord(string key, string default) </strong> <br/>
404 add an entry of the respective kind to the database. The name and default
405 value always has to be supplied, for <code>Mode</code> and
406 <code>Word</code> additionally if lower and/or upper limits are to be
407 imposed and, if so, what those limit are.
410 <a name="method11"></a>
411 <p/><strong>bool Settings::flag(string key) </strong> <br/>
413 <strong>int Settings::mode(string key) </strong> <br/>
415 <strong>double Settings::parm(string key) </strong> <br/>
417 <strong>string Settings::word(string key) </strong> <br/>
418 return the current value of the respective setting. If the name
419 does not exist in the database, a value <code>false</code>,
420 <code>0</code>, <code>0.</code> and <code>" "</code>
421 is returned, respectively.
424 <a name="method12"></a>
425 <p/><strong>map<string, Flag> Settings::getFlagMap(string match) </strong> <br/>
427 <strong>map<string, Mode> Settings::getModeMap(string match) </strong> <br/>
429 <strong>map<string, Parm> Settings::getParmMap(string match) </strong> <br/>
431 <strong>map<string, Word> Settings::getWordMap(string match) </strong> <br/>
432 return a map of all settings of the respective type that contain the
433 string "match" in its name.
436 <a name="method13"></a>
437 <p/><strong>void Settings::flag(string key, bool now) </strong> <br/>
439 <strong>void Settings::mode(string key, int now) </strong> <br/>
441 <strong>void Settings::parm(string key, double now) </strong> <br/>
443 <strong>void Settings::word(string key, string now) </strong> <br/>
444 change the current value of the respective setting to the provided
445 new value. If lower or upper limits have been set, input values
446 outside the allowed range are reinterpreted as being a the nearest
450 <a name="method14"></a>
451 <p/><strong>void Settings::forceMode(string key, int now) </strong> <br/>
453 <strong>void Settings::forceParm(string key, double now) </strong> <br/>
454 as above, but do not check lower and upper limits, so that the current
455 value can be put outside the intended borders.
458 <a name="method15"></a>
459 <p/><strong>void Settings::resetFlag(string key) </strong> <br/>
461 <strong>void Settings::resetMode(string key) </strong> <br/>
463 <strong>void Settings::resetParm(string key) </strong> <br/>
465 <strong>void Settings::resetWord(string key) </strong> <br/>
466 reset the current value to the default one.
472 <!-- Copyright (C) 2010 Torbjorn Sjostrand -->