如何仅计算R中特定行的列值

Question

I have to count total_buy/total sell of only column "A to D"...... it should not contain column "E to H"

Answer 1

Try to avoid inserting of pictures and check the solution:

dummy<-data.frame(A=sample(c("buy","sell"),100,replace = T),
           B=sample(c("buy","sell"),100,replace = T),
           C=sample(c("buy","sell"),100,replace = T),
           D=sample(c("buy","sell"),100,replace = T),
           E=sample(c("buy","sell"),100,replace = T),
           G=sample(c("buy","sell"),100,replace = T))

head(dummy)

     A    B    C    D    E    G
1  buy  buy sell sell  buy  buy
2  buy  buy  buy  buy  buy  buy
3  buy sell  buy  buy sell  buy
4 sell  buy  buy sell  buy sell
5 sell sell sell sell sell sell
6 sell sell  buy sell sell sell

Now apply the function with sapply on selected columns from 1:4 ie, A to D

sapply(dummy[1:4], function(x) table((x)))

OUTPUT :

      A  B  C  D
buy  50 53 53 51
sell 50 47 47 49