Re: [R] question about "mean"

2010-06-09 Thread Phil Spector
One possibility is aggregate(iris[,-5],list(iris[,5]),mean) Group.1 Sepal.Length Sepal.Width Petal.Length Petal.Width 1 setosa5.006 3.4281.462 0.246 2 versicolor5.936 2.7704.260 1.326 3 virginica6.588 2.9745

Re: [R] question about "mean"

2010-06-09 Thread Bill.Venables
: Re: [R] question about "mean" apply(iris[, -5], 2, tapply, iris$Species, mean) On Wed, Jun 9, 2010 at 3:43 PM, SH.Chou wrote: > Hi there: > I have a question about generating mean value of a data.frame. Take > iris data for example, if I have a data.frame looking

Re: [R] question about "mean"

2010-06-09 Thread Peter Langfelder
apply(iris[, -5], 2, tapply, iris$Species, mean) On Wed, Jun 9, 2010 at 3:43 PM, SH.Chou wrote: > Hi there: > I have a question about generating mean value of a data.frame. Take > iris data for example, if I have a data.frame looking like the following: > - >Sepal.Len

Re: [R] question about mean

2009-02-09 Thread Wacek Kusnierczyk
Rolf Turner wrote: > > On 9/02/2009, at 4:40 PM, bill.venab...@csiro.au wrote: > >> Store your 'matrix' as a data frame. > > Surely it's a data frame already, since ``school'' is character or > factor, > and ``value'' is (must be?) numeric. > > People have this unfortunate predilection

Re: [R] question about mean

2009-02-08 Thread Rolf Turner
On 9/02/2009, at 4:40 PM, bill.venab...@csiro.au wrote: Store your 'matrix' as a data frame. Surely it's a data frame already, since ``school'' is character or factor, and ``value'' is (must be?) numeric. People have this unfortunate predilection to refer to data frames a

Re: [R] question about mean

2009-02-08 Thread Bill.Venables
Store your 'matrix' as a data frame. Call it 'SchoolVals' say. Then SchoolMeans <- with(SchoolVals, tapply(value, school, mean)) should do it. If you have missing values you want to ignore: SchoolMeans <- with(SchoolVals, tapply(value, school, mean, na.rm = TRUE)) Bill Venables http://www