On 8/7/2008 7:01 AM, glaporta wrote:
Hi folk,
I tried this and it works just perfectly
tapply(iris[,1],iris[5],mean)
but, how to obtain a single table from multiple variables?
In tapply x is an atomic object so this code doesn't work
tapply(iris[,1:4],iris[5],mean)
Thanx and great summer holidays
Gianandrea
Here is one way:
> apply(iris[,1:4], 2, function(x){tapply(x, list(iris[,5]), mean)})
Sepal.Length Sepal.Width Petal.Length Petal.Width
setosa 5.006 3.428 1.462 0.246
versicolor 5.936 2.770 4.260 1.326
virginica 6.588 2.974 5.552 2.026
Here is another:
> library(reshape)
> iris.melt <- melt(iris, measure.var=names(iris)[1:4])
> cast(iris.melt, variable + Species ~ ., mean)
variable Species (all)
1 Sepal.Length setosa 5.006
2 Sepal.Length versicolor 5.936
3 Sepal.Length virginica 6.588
4 Sepal.Width setosa 3.428
5 Sepal.Width versicolor 2.770
6 Sepal.Width virginica 2.974
7 Petal.Length setosa 1.462
8 Petal.Length versicolor 4.260
9 Petal.Length virginica 5.552
10 Petal.Width setosa 0.246
11 Petal.Width versicolor 1.326
12 Petal.Width virginica 2.026
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