r - How to score an exam grade -

my df is:

--id   q1 q2 q3 q4 q5 q6 q7  1 112    b  c  d   d  c 2 222   e  b  c    d  c 3 342   d  c  c   d  c  d 4 454    b  d  e  c  b  5 554     c    d  d 6 136   b   d   e  d  

i have solution:

solution= c(0, a, b, c,a, d, d, a) 

i wanted know if there score function use see how many right answers got compared solution.

we can try rowsums after creating logical matrix

rowsums(df[-1] == solution[col(df[-1])]) #1 2 3 4 5 6  #4 4 3 3 4 3  

data

solution <-  c('a', 'b', 'c','a', 'd', 'd', 'a')