[R] Count unchanged class attribute

[Soe Xiyan]

Maybe someone can help me.
Suppose I have data-set like this:

  Netto   Bruto  class
1 10      1000    yes
2 100     20      yes


  Netto   Bruto  class
1 101     1000    yes
2 100     210     no


  Netto   Bruto  class
1 10      10      yes
2 12      28      yes
3 100     20      yes

  Netto   Bruto  class
1 120     200     no
2 400     20      yes


  Netto   Bruto  class
1 110     12000   yes
2 1100    120     yes
3 120     100     yes
4 1140    125     yes

How to calculate the number of classes has changed.
The expected result is
- class changed    2
- class unchanged  3


Thank you so much.
Soe Xiyan

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