3 <title>The Settings Scheme</title>
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9 <h2>The Settings Scheme</h2>
11 The <code>Settings</code> class keeps track of all the flags, modes,
12 parameters and words used during the event generation. As such, it
13 serves all the <code>Pythia</code> program elements from one central
14 repository. Accessing it allows the user to modify the generator
18 Each <code>Pythia</code> object has a public member <code>settings</code>
19 of the <code>Settings</code> class. Therefore you access the
20 settings methods as <code>pythia.settings.command(argument)</code>,
21 assuming that <code>pythia</code> is an instance of the <code>Pythia</code>
22 class. Further, for the most frequent user tasks, <code>Pythia</code>
23 methods have been defined, so that <code>pythia.command(argument)</code>
24 would work, see further below.
27 The central section on this page is the Operation one. The preceding
28 concepts section is there mainly to introduce the basic structure and
29 the set of properties that can be accessed. The subsequent sections
30 provide a complete listing of the existing public methods, which most
31 users probably will have little interaction with.
35 We distinguish four kinds of user-modifiable variables, by the way
36 they have to be stored:
38 <li>Flags are on/off switches, and are stored as <code>bool</code>.</li>
39 <li>Modes corresponds to a finite enumeration of separate options,
40 and are stored as <code>int</code>.</li>
41 <li>Parameters take a continuum of values, and are stored as
42 <code>double</code>. The shorthand notation parm is used in the C++
43 code and XML tags, so that all four kinds are represented by
44 four-letter type names.</li>
45 <li>Words are simple character strings and are stored as
46 <code>string</code>. No blanks or double quotation marks (") may
47 appear inside a word, the former to simplify parsing of an input file
48 and the latter not to cause conflicts with XML attribute delimiters.
49 Currently the main application is to store file names.</li>
53 In general, each variable stored in <code>Settings</code> is associated
54 with four kinds of information:
56 <li>The variable name, of the form <code>class:name</code>
57 (or <code>file:name</code>, usually these agree), e.g.
58 <code>TimeShower:pTmin</code>. The class/file part usually identifies
59 the <code>.xml</code> file where the variable is defined, and the part of
60 the program where it is used, but such a connection cannot be strictly
61 upheld, since e.g. the same variable may be used in a few different
62 cases (even if most of them are not).</li>
63 <li>The default value, set in the original declaration, and intended
64 to represent a reasonable choice.</li>
65 <li>The current value, which differs from the default when the user so
67 <li>An allowed range of values, represented by meaningful
68 minimum and maximum values. This has no sense for a <code>flag</code>
69 or a <code>word</code> (and is not used there), is usually rather
70 well-defined for a <code>mode</code>, but less so for a <code>parm</code>.
71 Often the allowed range exaggerates the degree of our current knowledge,
72 so as not to restrict too much what the user can do. One may choose
73 not to set the lower or upper limit, in which case the range is
78 Technically, the <code>Settings</code> class is implemented with the
79 help of four separate maps, one for each kind of variable, with the
80 variable <code>name</code> used as key.
84 The normal flow of setting values is:
89 When a <code>Pythia</code> object <code>pythia </code>is created,
90 the member <code>pythia.settings</code> is asked to scan the files
91 listed in the <code>Index.xml</code> file in the <code>xmldoc</code>
95 In all of the files scanned, lines beginning with
96 <code><flag</code>, <code><mode</code>, <code><parm</code>
97 or <code><word</code> are identified, and the information on
98 such a line is used to define a new flag, mode, parameter or word.
99 To exemplify, consider a line
101 <parm name="TimeShower:pTmin" default="0.5" min="0.1" max="2.0">
103 which appears in the <code>TimeShower.xml</code> file, and there
104 defines a parameter <code>TimeShower:pTmin</code> with default value
105 0.5 GeV and allowed variation in the range 0.1 - 2.0 GeV. The min
106 and max values are optional.
107 <br/><b>Important:</b> the values in the <code>.xml</code> files should
108 not be changed, except by the PYTHIA authors. Any changes should be
109 done with the help of the methods described below.
113 Between the creation of the <code>Pythia</code> object and the
114 <code>init</code> call for it, you may use several alternative
115 methods to modify some of the default values. The same variable
116 can be changed several times. If so, it is the last read value
117 that counts. The two special
118 <code><a href="Tunes.html" target="page">Tune:ee</a></code> and
119 <code><a href="Tunes.html" target="page">Tune:pp</a></code>
120 modes are expanded to change several settings in one go, but these obey
121 the same ordering rules.
124 a) Inside your main program you can directly set values with
126 pythia.readString(string)
128 where both the variable name and the value are contained inside
129 the character string, separated by blanks and/or a =, e.g.
131 pythia.readString("TimeShower:pTmin = 1.0");
133 The match of the name to the database is case-insensitive. Names
134 that do not match an existing variable are ignored. A warning is
135 printed, however. Strings beginning with a non-alphanumeric character,
136 like # or !, are assumed to be comments and are not processed at all.
137 Values below the minimum or above the maximum are set at
138 the respective border. For <code>bool</code> values, the following
139 notation may be used interchangeably:
140 <code>true = on = yes = ok = 1</code>, while everything else gives
141 <code>false</code> (including but not limited to
142 <code>false</code>, <code>off</code>, <code>no</code> and 0).<br/>
145 b) The <code>Pythia</code> <code>readString(string)</code> method
146 actually does not do changes itself, but sends on the string either
147 to the <code>Settings</code> class or to <code>ParticleData</code>.
148 The former holds if the string begins with a letter, the latter
149 if it begins with a digit. If desired, it is possible to communicate
150 directly with the corresponding <code>Settings</code> method:
152 pythia.settings.readString("TimeShower:pTmin = 1.0");
154 In this case, changes intended for <code>ParticleData</code>
155 would not be understood.
158 c) Underlying the <code>settings.readString(string)</code> method are
159 the settings-type-sensitive commands in the <code>Settings</code>, that
160 are split by names containing <code>flag</code>, <code>mode</code>,
161 <code>parm</code> or <code>word</code>. Thus, the example now reads
163 pythia.settings.parm("TimeShower:pTmin", 1.0);
165 Such a form could be convenient e.g. if a parameter is calculated
166 at the beginning of the main program, and thus is available as a
167 variable rather than as a character string.
168 Note that Boolean values must here be given as <code>true</code> or
169 <code>false</code> i.e. there is less flexibility than with the
173 At the same level, there are several different methods available.
174 These are included in the full description below, but normally the user
175 should have no need for them.
178 d) A simpler and more useful way is to collect all your changes
179 in a separate file, with one line per change, e.g.
181 TimeShower:pTmin = 1.0
183 Each line is read in as a string and processed with the methods already
186 The file can be read by the
188 pythia.readFile(fileName);
190 method (or an <code>istream</code> instead of a <code>fileName</code>).
191 The file can freely mix commands to the <code>Settings</code> and
192 <code>ParticleData</code> classes, and so is preferable. Lines with
193 settings are handled by calls to the
194 <code>pythia.settings.readString(string)</code> method.
198 In the <code>pythia.init(...)</code> call, many of the various other program
199 elements are initialized, making use of the current values in the database.
200 Once initialized, the common <code>Settings</code> database is likely not
201 consulted again by these routines. It is therefore not productive to do
202 further changes in mid-run: at best nothing changes, at worst you may
203 set up inconsistencies.
206 A routine <code>reInit(fileName)</code> is provided, and can be used to
207 zero all the maps and reinitialize them from scratch. Such a call might be
208 useful if several subruns are to be made with widely different parameter
209 sets - normally the maps are only built from scratch once, namely when the
210 <code>Pythia()</code> object is created. A more economical alternative is
211 offered by <code>resetAll()</code>, however, which sets all variables back
212 to their default values.
216 You may at any time obtain a listing of all variables in the
219 pythia.settings.listAll();
221 The listing is strictly alphabetical, which at least means that names
222 from the same file are kept together, but otherwise may not be so
223 well-structured: important and unimportant ones will appear mixed.
224 A more relevant alternative is
226 pythia.settings.listChanged();
228 where you will only get those variables that differ from their
229 defaults. Or you can use
231 pythia.settings.list("string");
233 where only those variables with names that contain the string
234 (case-insensitive match) are listed. Thus, with a string
235 <code>shower</code>, the shower-related variables would be shown.
239 The above listings are in a tabular form that cannot be read
240 back in. Assuming you want to save all changed settings (maybe because
241 you read in changes from several files), you can do that by calling
243 pythia.settings.writeFile(fileName);
245 This file could then directly be read in by
246 <code>readFile(fileName)</code> in a subsequent (identical) run.
247 Some variants of this command are listed below.
253 The complete list of methods and arguments is as follows. Most of the
254 ones of interest to the user have already been mentioned above.
255 Others can be used, but the same functionality is better achieved
256 by higher-level routines. Some are part of the internal machinery,
257 and should not be touched by user.
260 Note that there is no <code>Settings::readFile(...)</code> method.
261 The intention is that you should use <code>Pythia::readFile(...)</code>.
262 It parses and decides which individual lines should be sent on to
263 <code>Settings::readString(...)</code>.
265 <a name="method1"></a>
266 <p/><strong>Settings::Settings() </strong> <br/>
267 the constructor, which takes no arguments. Internal.
270 <a name="method2"></a>
271 <p/><strong>bool Settings::initPtr(Info* infoPtrIn) </strong> <br/>
272 initialize pointer to error-message database. Internal.
275 <a name="method3"></a>
276 <p/><strong>bool Settings::init(string startFile = "../xmldoc/Index.xml", bool append = false, ostream& os = cout) </strong> <br/>
277 read in the settings database.
278 <br/><code>argument</code><strong> startFile </strong> (<code>default = <strong>"../xmldoc/Index.xml"</strong></code>) :
279 read in the settings from all the files listed in this file, and
280 assumed to be located in the same subdirectory.
282 <br/><code>argument</code><strong> append </strong> (<code>default = <strong>false</strong></code>) :
283 By default nothing is done if the method has already been called once.
284 If true the further settings read in are added to the current database.
286 <br/><code>argument</code><strong> os </strong> (<code>default = <strong>cout</strong></code>) :
287 stream for error printout.
289 <br/><b>Note:</b> The method returns false if it fails.
292 <a name="method4"></a>
293 <p/><strong>bool Settings::reInit(string startFile = "../xmldoc/Index.xml", ostream& os = cout) </strong> <br/>
294 overwrite the existing database.
295 <br/><code>argument</code><strong> startFile </strong> (<code>default = <strong>"../xmldoc/Index.xml"</strong></code>) :
296 read in the settings from all the files listed in this file, and
297 assumed to be located in the same subdirectory.
299 <br/><code>argument</code><strong> os </strong> (<code>default = <strong>cout</strong></code>) :
300 stream for error printout.
302 <br/><b>Note:</b> The method returns false if it fails.
305 <a name="method5"></a>
306 <p/><strong>bool Settings::readString(string line, bool warn = true, ostream& os = cout) </strong> <br/>
307 read in a string, and change the relevant quantity in the database.
308 It is normally used indirectly, via
309 <code>Pythia::readString(...)</code> and
310 <code>Pythia::readFile(...)</code>.
311 <br/><code>argument</code><strong> line </strong> :
312 the string to be interpreted as an instruction.
314 <br/><code>argument</code><strong> warn </strong> (<code>default = <strong>true</strong></code>) :
315 write a warning message or not whenever the instruction does not make
316 sense, e.g. if the variable does not exist in the databases.
318 <br/><code>argument</code><strong> os </strong> (<code>default = <strong>cout</strong></code>) :
319 stream for error printout.
321 <br/><b>Note:</b> the method returns false if it fails to
322 make sense out of the input string.
325 <a name="method6"></a>
326 <p/><strong>bool Settings::writeFile(string toFile, bool writeAll = false) </strong> <br/>
328 <strong>bool Settings::writeFile(ostream& os = cout, bool writeAll = false) </strong> <br/>
329 write current settings to a file or to an <code>ostream</code>.
330 <br/><code>argument</code><strong> toFile, os </strong> :
331 file or stream on which settings are written.
333 <br/><code>argument</code><strong> writeAll </strong> (<code>default = <strong>false</strong></code>) :
334 normally only settings that have been changed are written,
335 but if true then all settings are output.
337 <br/><b>Note:</b> the method returns false if it fails.
340 <a name="method7"></a>
341 <p/><strong>void Settings::listAll(ostream& os = cout) </strong> <br/>
343 <strong>void Settings::listChanged(ostream& os = cout) </strong> <br/>
345 <strong>void Settings::list(string match, ostream& os = cout) </strong> <br/>
346 list all or changed settings, or a group of them.
347 <br/><code>argument</code><strong> match </strong> :
348 list all those settings where the name contains
349 the <code>match</code> (sub)string (case-insensitive).
351 <br/><code>argument</code><strong> os </strong> (<code>default = <strong>cout</strong></code>) :
352 output stream for the listing.
356 <a name="method8"></a>
357 <p/><strong>void Settings::resetAll() </strong> <br/>
358 reset all current values to their defaults.
361 <a name="method9"></a>
362 <p/><strong>bool Settings::isFlag(string key) </strong> <br/>
364 <strong>bool Settings::isMode(string key) </strong> <br/>
366 <strong>bool Settings::isParm(string key) </strong> <br/>
368 <strong>bool Settings::isWord(string key) </strong> <br/>
369 return true if an entry of the given name and kind
373 <a name="method10"></a>
374 <p/><strong>void Settings::addFlag(string key, bool default) </strong> <br/>
376 <strong>void Settings::addMode(string key, int default, bool hasMin, bool hasMax, int min, int max) </strong> <br/>
378 <strong>void Settings::addParm(string key, double default, bool hasMin, bool hasMax, double min, double max) </strong> <br/>
380 <strong>void Settings::addWord(string key, string default) </strong> <br/>
381 add an entry of the respective kind to the database. The name and default
382 value always has to be supplied, for <code>Mode</code> and
383 <code>Word</code> additionally if lower and/or upper limits are to be
384 imposed and, if so, what those limit are.
387 <a name="method11"></a>
388 <p/><strong>bool Settings::flag(string key) </strong> <br/>
390 <strong>int Settings::mode(string key) </strong> <br/>
392 <strong>double Settings::parm(string key) </strong> <br/>
394 <strong>string Settings::word(string key) </strong> <br/>
395 return the current value of the respective setting. If the name
396 does not exist in the database, a value <code>false</code>,
397 <code>0</code>, <code>0.</code> and <code>" "</code>
398 is returned, respectively.
401 <a name="method12"></a>
402 <p/><strong>map<string, Flag> Settings::getFlagMap(string match) </strong> <br/>
404 <strong>map<string, Mode> Settings::getModeMap(string match) </strong> <br/>
406 <strong>map<string, Parm> Settings::getParmMap(string match) </strong> <br/>
408 <strong>map<string, Word> Settings::getWordMap(string match) </strong> <br/>
409 return a map of all settings of the respective type that contain the
410 string "match" in its name.
413 <a name="method13"></a>
414 <p/><strong>void Settings::flag(string key, bool now) </strong> <br/>
416 <strong>void Settings::mode(string key, int now) </strong> <br/>
418 <strong>void Settings::parm(string key, double now) </strong> <br/>
420 <strong>void Settings::word(string key, string now) </strong> <br/>
421 change the current value of the respective setting to the provided
422 new value. If lower or upper limits have been set, input values
423 outside the allowed range are reinterpreted as being a the nearest
427 <a name="method14"></a>
428 <p/><strong>void Settings::forceMode(string key, int now) </strong> <br/>
430 <strong>void Settings::forceParm(string key, double now) </strong> <br/>
431 as above, but do not check lower and upper limits, so that the current
432 value can be put outside the intended borders.
435 <a name="method15"></a>
436 <p/><strong>void Settings::resetFlag(string key) </strong> <br/>
438 <strong>void Settings::resetMode(string key) </strong> <br/>
440 <strong>void Settings::resetParm(string key) </strong> <br/>
442 <strong>void Settings::resetWord(string key) </strong> <br/>
443 reset the current value to the default one.
449 <!-- Copyright (C) 2010 Torbjorn Sjostrand -->