如何根據條件做一個累計計數？

Question

我有這樣一個數據幀：

val1,val2 
    0, 0 
    0, 0 
    1, 1 
    1, 0 
    1, 1 

我想要做的每一次VAL1是做一個累積計數和val2不同意

val1,val2, cum_count 
    0, 0, 1 
    0, 0, 2 
    1, 1, 3 
    1, 0, 3 <--- the value here doesn't changes as val1 and val2 disagrees 
    1, 1, 4 

如何在r中做到這一點？

Answer 1

dd$cum_count <- with(dd, cumsum(val1==val2))