titanic surviving test

Question

i have a problem my output is logical(0)
this is my code
but i still dont what is the problem

x <- x[x$age >= 18, ]

res<-by(x$Pclass, x$Survived, mean)
print(res)

Answer 1

Use tapply instead of by, and don't assign to res and don't use print, and also remember to read the csv file and assign it to x.

Answer 2

It is Age with capital A. And, as already mentioned, try tapply()

Answer 3

Lisa Yes, that's rigth with capital A.