tapply bug? - levels of a factor in a data frame after tapply are intermixed
Think of the levels as a table you are going to index into. The factors that you see (2, 1, 3) are the indices into the levels so you get 9, 3, 15 as the result. What were you expecting? It is working as it is supposed to.
On Fri, Feb 13, 2009 at 12:09 PM, Dimitri Liakhovitski <ld7631 at gmail.com> wrote:
Hello! I have encountered a really weird problem. Maybe you've
encountered it before?
I have a large data frame "importances". It has one factor ($A) with 3
levels: 3, 9, and 15. $B is a regular numeric variable.
Below I am picking a really small sub-frame (just 3 rows) based on
"indices". "indices" were chosen so that all 3 levels of A are
present:
indices=c(14329,14209,14353)
test=data.frame(yy=importances[["B']][indices],xx=importances[["A"]][indices])
Here is what the new data frame "test" looks like:
yy xx
1 -0.009984006 9
2 -2.339904131 3
3 -0.008427385 15
Here is the structure of "test":
str(test)
'data.frame': 3 obs. of 2 variables: $ yy: num -0.00998 -2.3399 -0.00843 $ xx: Factor w/ 3 levels "3","9","15": 2 1 3 Notice - the order of factor levels for xx is not 1 2 3 as it should be but 2 1 3. How come? Or also look at this:
test$xx
[1] 9 3 15 Levels: 3 9 15 Same thing. Do you know what might be the reason? Thank you very much! -- Dimitri Liakhovitski MarketTools, Inc. Dimitri.Liakhovitski at markettools.com
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