Re: [R] how to make partial mean() of a matrix only when second value matching some logic

try tapply() if you want the values for all levels of x, or calculate your mean after a subset() Check the documentation on both of these. Mike On Wed, Dec 8, 2010 at 9:54 AM, madr wrote: > > for example I have matrix with two columns > > x,y > 1,0.56 > 2,9.55 > 2,7.56 > 5,2.55 > 5,0.56 > 3,0.

[R] how to make partial mean() of a matrix only when second value matching some logic

for example I have matrix with two columns x,y 1,0.56 2,9.55 2,7.56 5,2.55 5,0.56 3,0.55 2,0.56 2,1.56 so I need to take average from y values placed where x==2 -- View this message in context: http://r.789695.n4.nabble.com/how-to-make-partial-mean-of-a-matrix-only-when-second-value-matching-s