[R] How to calculate?

[Erik Iverson]

see ?tapply, for example:

tapply(df$x, df$z, mean)

Might also look at ?ave and ?aggregate depending on what form you want 
the result to have... or the "plyr" package on CRAN.  Lots of options!


stat4u wrote:
> hi,
> How can i calculate means with catergory of variable...
> 
> like
> 
> x   y    z
> 2   3    y
> 3   4    n
> 1   2    y
> 6   3    n
> 9   1    y
> 2   2    n
> 8   3    y
> 
> i want to get mean of x and y with respective to  its category(y,n)
> 
> thanks...
> regards,
> Muhammad Faisal