ENTROPIA #es.positivi #es.negativi Entropia ---------------------------------------------- 1 2 0.918296 1 3 0.811278 1 4 0.721928 1 5 0.650022 1 6 0.591673 1 7 0.543564 1 8 0.503258 1 9 0.468996 2 3 0.970951 2 4 0.918296 2 5 0.863121 2 6 0.811278 2 7 0.764204 2 8 0.721928 2 9 0.684038 3 4 0.985228 3 5 0.954434 3 6 0.918296 3 7 0.881291 3 8 0.845351 3 9 0.811278 4 5 0.991076 4 6 0.970951 4 7 0.945660 4 8 0.918296 4 9 0.890492 5 6 0.994030 5 7 0.979869 5 8 0.961237 5 9 0.940286 6 7 0.995727 6 8 0.985228 6 9 0.970951 7 8 0.996792 7 9 0.988699 8 9 0.997503 ---------------------------------------------- Ricordate che l'entropia e' una funzione simmetrica; ad esempio: l'entropia di 2 esempi positivi e 1 esempio negativo e' uguale all'entropia di 2 esempi negativi e 1 positivo. LOGARITMI BASE 2 (per calcolare SplitInformation) log2(1/2) = -1.000000 log2(1/3) = -1.584962 log2(1/4) = -2.000000 log2(1/5) = -2.321928 log2(1/6) = -2.584962 log2(1/7) = -2.807355 log2(1/8) = -3.000000 log2(1/9) = -3.169925 log2(1/10) = -3.321928 log2(1/11) = -3.459432 log2(2/3) = -0.584962 log2(2/5) = -1.321928 log2(2/7) = -1.807355 log2(2/9) = -2.169925 log2(2/11) = -2.459432 log2(3/4) = -0.415037 log2(3/5) = -0.736966 log2(3/7) = -1.222392 log2(3/8) = -1.415037 log2(3/10) = -1.736966 log2(3/11) = -1.874469 log2(4/5) = -0.321928 log2(4/7) = -0.807355 log2(4/9) = -1.169925 log2(4/11) = -1.459432 log2(5/6) = -0.263034 log2(5/7) = -0.485427 log2(5/8) = -0.678072 log2(5/9) = -0.847997 log2(5/11) = -1.137503 log2(6/7) = -0.222392 log2(6/11) = -0.874469 log2(7/8) = -0.192645 log2(7/9) = -0.362570 log2(7/10) = -0.514573 log2(7/11) = -0.652077 log2(8/9) = -0.169925 log2(8/11) = -0.459432 log2(9/10) = -0.152003 log2(9/11) = -0.289507 log2(10/11) = -0.137504