java - What's a quick hash, which will map UUIDs to the unit interval? -


i'm looking hash uuids unit interval, on hot path application.

this sounds should have been efficiently solved, searches haven't yet turned solution. know of (and have reference sample implementation) quick/efficient hash of uuids unit interval (obviously while preserving of random distribution possible).

this method keeps "uniqueness level" of uuid one-to-one bijection of each large number corresponding float number on interval between [1/maxuuid,1].

after removing hyphens, uuid string simple hex string. convert bigint , divide maximal possible uuid-number(128 bit ff...fff).

string hexuuid = uuidstr.replaceall('-',''); bigdecimal uuid = new bigdecimal(new biginteger(hexuuid , 16)); bigdecimal maximal = new bigdecimal(new biginteger("ffff...ff",16)); // compute once!! bigdecimal floatid = uuid.divide(maximal, mathcontext.decimal128);

probably, have play characters case (to lowercase before converting number), play big decimal divide parameters (scale, rounding mode) main idea presented in code above.


Comments

Post a Comment

Popular posts from this blog

javascript - Using jquery append to add option values into a select element not working -

i'm looking dynamically populate select element names of items stored array. for reason it's not working , i'm not sure why. html: <div class="col-md-4 col-md-offset-4"> <select class="select1"> </select> , <select class="select2"> </select> </div> note i'm using bootstrap layout. here's jquery i'm using try , populate ".select1" jquery: select: function() { $.each(state.greens, function(index, value) { $(".select1").append("<option value =' " + index + " '>" + state.greens[index].name + "</option>"); }); } note function 'select' stored within object called 'display'. state.greens name of array i'm trying access. so @ end of html page call display.select(); call function. no error messages showing in console. also, saw question: appending
Read more

Android soft keyboard reverts to default keyboard on orientation change -

i'm building android soft keyboard , can't seem fix bug - have arabic , qwerty keyboard , when rotate device on qwerty keyboard (or arabic shift), it's if program has "restarted" , becomes arabic keyboard without shift. the onsaveinstancestate(bundle savedinstancestate) not work because application not extend activity inputmethodservice . i put following in android manifest android:configchanges="keyboard|keyboardhidden|orientation" android:windowsoftinputmode="stateunchanged|adjustresize"> i tried using @override public void onconfigurationchanged(configuration newconfig) { super.onconfigurationchanged(newconfig); log.i(mydebug, "config changed " + currentkeyboard.equals(qwerty)); } however, currentkeyboard.equals(qwerty)) results false , made sure true before orientation change. any appreciated. i think applications fault. if application restarting on orientation change
Read more

jquery - javascript onscroll fade same class but with different div -

i new @ javascript , want learn new. there wrong code : why div fades @ same time. i want ask how fade different div s same class name.can me , explain me. thanks in advance. javascript: $(window).scroll(function(){ if ($( "div.fade" ).offset().top - $(window).scrolltop() <= 100){ $('.fade').addclass( "fade-in"); } else { $('.fade').removeclass("fade-in"); } }); here jsfiddle onscroll = function () { var scrolltop = $(this).scrolltop() ; $("div.fade").each(function(){ if(($(this).offset().top - scrolltop) <= 100){ $(this).toggleclass("fade-in"); } }) }
Read more