python - Inverting permutations witn sympy -

-

what function in sympy.combinatorics.permutations can return inverse permutation of given permutation? searches in google don't give results. can write function, if such has been implemented in sympy, unnecessary.

thanks help!

you're looking ~:

in [5]: print permutation.__invert__.__doc__         return inverse of permutation.         permutation multiplied inverse identity permutation.         examples         ========         >>> sympy.combinatorics.permutations import permutation         >>> p = permutation([[2,0], [3,1]])         >>> ~p         permutation([2, 3, 0, 1])         >>> _ == p**-1         true         >>> p*~p == ~p*p == permutation([0, 1, 2, 3])         true  in [6]: ~permutation(1, 2, 0) out[6]: permutation(0, 2, 1)

** -1 works. online documentation literally never explains this, can see how didn't find it. ~ mentioned in explanations of commutator , mul_inv methods.


Comments

Post a Comment

Popular posts from this blog

ios - Memory not freeing up after popping viewcontroller using ARC -

-
hi project arc based, using uinavigationcontroller make transition between viewcontroller. using profiler analyse happening behind scene memory. noticed when push viewcontroller allocate memory components , when pop not freeing allocated memory. since using arc unable implement dealloc or release component. have analysed in detail , there no memory leak in project. i not using strong property push viewcontroller. here how pushing viewcontroller. viewcontroller *obj = [[viewcontroller alloc] init]; [self.navigationcontroller pushviewcontroller:obj animated:no]; any clue whats going on? should free memory have consumed. please advise your description indicates have retain cycle, leads objects not being deallocated. typical source of retain cycles properties assigned loading nib files (usually declared iboutlet ). two strategies break them , release objects: declare property weak : @property (nonatomic, weak) iboutlet uilabel *statuslabel; set property nil in...
Read more

mouseevent - Catch mouse event on tree widget item in QTreeWidget -

-
in tree widget have following signal connected: connect(mtreewidget, signal(itemclicked(qtreewidgetitem*, int)), slot(onitemclicked(qtreewidgetitem*, int))); where onitemclicked() slot following: void widgetbox::onitemclicked(qtreewidgetitem *item, int ) { int index = getpageindex(item); setcurrentindex(index); } int widgetbox::getpageindex(qtreewidgetitem *item) { if (!item) return -1; qtreewidgetitem *parent = item->parent(); if(parent) // parent top level item { return mtreewidget->indexoftoplevelitem(parent); } else // current item top level { return item->treewidget()->indexoftoplevelitem(item); } } void widgetbox::setcurrentindex(int index) { if (index != currentindex() && checkindex(index)) { mtreewidget->setcurrentitem(mtreewidget->toplevelitem(index)); emit currentindexchanged(index); } } however can't catch itemclicked() signal , onitemclicked() never executed because...
Read more

Java JSoup error fetching URL -

-
i'm creating application enable me fetch values specific website console. value <span> element , i'm using jsoup . my challenge has error: error fetching url here java code: public class testsl { public static void main(string[] args) throws ioexception { document doc = jsoup.connect("https://stackoverflow.com/questions/11970938/java-html-parser-to-extract-specific-data").get(); elements spans = doc.select("span[class=hidden-text]"); (element span: spans) { system.out.println(span.text()); } } } and here error on console: exception in thread "main" org.jsoup.httpstatusexception: http error fetching url. status=403, url= java html parser extract specific data? @ org.jsoup.helper.httpconnection$response.execute(httpconnection.java:590) @ org.jsoup.helper.httpconnection$response.execute(httpconnection.java:540) @ org.jsoup.helper.httpconnection.execute...
Read more