Simulating abrupt data streams why are the means the same after the split ? thank you

[G Smith]

Hello all,

Thank you to all the MOA team for all your hard work and all any advice much

appreciated  to my question below

Thank you

Gregory

Question I am having issues understanding streams

A simple example is as below

I called the command from MOA below  which should  generate a stream of 50 instances  the two streams Stream A 25 instances

 and Stream B 25 instances should split at instance 25 over an interval of 1

MOA Command
WriteStreamToARFFFile -s (ConceptDriftStream -s (generators.SEAGenerator -f 3) -d (generators.SEAGenerator -f 2) -p 25 -w 1) -f example2_sm25.arff -m 50

I was expecting that mean number of Group A's and Group B's to differ after the split
instances 1-25,25,50 to have a different count of Group B's but they don't !!! Why I ask

I copied the below into excel did a countif
=COUNTIF(D2:D24,"=GroupB") = 16
=COUNTIF(D26:D51,"=GroupB") = 17

I don't understand I thought there should be a different number of B's in each group after the abrupt split :




Output

@relation 'generators.SEAGenerator -f 3'

@attribute attrib1 numeric
@attribute attrib2 numeric
@attribute attrib3 numeric
@attribute class {groupA,groupB}

@data

7.308781907032909,4.100808114922017,2.077148413097171,groupB,
6.588672394716129,7.107396275716601,1.5273620134152177,groupB,
9.398653887819098,9.471949176631938,9.370821488959697,groupB,
9.139628760146802,1.5933955153907886,3.6900255838757188,groupB,
1.1596708803265776,7.705358800791777,6.5989270869342,groupB,
7.6167469290199925,6.23972537215988,8.7926296435219,groupB,
8.052277714737137,0.050251759924525574,5.231351557883331,groupA,
7.050099543038414,2.750299495716141,0.7538779891363978,groupB,
5.771002613742765,2.0491354575856158,6.233638106316658,groupB,
0.012985767526091374,6.835265034592647,4.862595823117322,groupA,
5.403970647837965,9.738340099187003,2.454265535812956,groupB,
8.456556680441219,4.065408324004243,9.498398487740127,groupA,
8.89908751655377,0.3832689331927541,5.923792438629388,groupB,
2.2880198240040297,9.918821104239925,5.8624839759353975,groupA,
2.0673750736050733,3.7464950029397013,4.633497875694758,groupA,
2.9073219661731207,0.5144836759769278,1.8354019521148224,groupA,
6.304048639228538,9.095840355890243,5.076599160699481,groupB,
1.1667030198550488,1.3683046859641235,5.460894065696358,groupA,
9.624145927337464,2.0949273346356434,1.7264882091400524,groupB,
8.011570655624329,1.0984105747663708,5.187868593512572,groupB,
6.9900662243448055,2.0463555220568552,2.549094512998157,groupB,
1.7437109686467622,6.9959157680128765,9.289718539061933,groupB,
8.363149477563287,1.6310352738831468,6.374974298594064,groupB,
6.544260178683681,3.7287330937352725,9.105662089639498,groupB,
7.070442260539652,7.233716462158025,5.094929196703692,groupB,
7.308781907032909,4.100808114922017,2.077148413097171,groupB,
6.588672394716129,7.107396275716601,1.5273620134152177,groupB,
9.398653887819098,9.471949176631938,9.370821488959697,groupB,
9.139628760146802,1.5933955153907886,3.6900255838757188,groupB,
1.1596708803265776,7.705358800791777,6.5989270869342,groupA,
7.6167469290199925,6.23972537215988,8.7926296435219,groupB,
8.052277714737137,0.050251759924525574,5.231351557883331,groupB,
7.050099543038414,2.750299495716141,0.7538779891363978,groupB,
5.771002613742765,2.0491354575856158,6.233638106316658,groupA,
0.012985767526091374,6.835265034592647,4.862595823117322,groupA,
5.403970647837965,9.738340099187003,2.454265535812956,groupB,
8.456556680441219,4.065408324004243,9.498398487740127,groupA,
8.89908751655377,0.3832689331927541,5.923792438629388,groupB,
2.2880198240040297,9.918821104239925,5.8624839759353975,groupA,
2.0673750736050733,3.7464950029397013,4.633497875694758,groupA,
2.9073219661731207,0.5144836759769278,1.8354019521148224,groupA,
6.304048639228538,9.095840355890243,5.076599160699481,groupB,
1.1667030198550488,1.3683046859641235,5.460894065696358,groupA,
9.624145927337464,2.0949273346356434,1.7264882091400524,groupB,
8.011570655624329,1.0984105747663708,5.187868593512572,groupB,
6.9900662243448055,2.0463555220568552,2.549094512998157,groupB,
1.7437109686467622,6.9959157680128765,9.289718539061933,groupA,
8.363149477563287,1.6310352738831468,6.374974298594064,groupB,
6.544260178683681,3.7287330937352725,9.105662089639498,groupB,
7.070442260539652,7.233716462158025,5.094929196703692,groupB,