The message is really explicit.

You are trying to compare the equality of two factors with different level

sets. Such factors are not comparable (and this is discussed on ?factor).

You didn't give a reproducible example, and you have not told us what you

are trying to do, so all we can do is repeat R's report that what you

actually did is not sensible.

On Sat, 7 Jan 2006, Richard van Wingerden wrote:

> Hi,

>

> I have two data frames A en B.

> I want to filter B with values of A

>

> data_frame_b

> names <- colnames(data_frame_b[1:1, ])

>

> filtera <- data.frame(data_frame_a[1:1])

This is bit strange. data_frame_a[1:1] is data_frame_a[1] and is a

single-column data-frame. I think you might just as well use

filtera <- data_frame_a[[1]]

which is (probably) a factor. You then seem to want to extract values

equal to its first element, so maybe you actually wanted

columnX == as.character(data_frame_a[1,1]) ?

>

> print(nrow(filtera))

>

> if (nrow(filtera)>0){

>

> filtered_frame_b <- subset(data_frame_b, ColumnX == filtera[1, 1], names)

> }

> The results are:

>

> [1] 124

> Error in Ops.factor(ColumnX, filtera[1, 1]) :

> level sets of factors are different

>

>

> What is wrong??

>

> Richard

--

Brian D. Ripley,

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Professor of Applied Statistics,

http://www.stats.ox.ac.uk/~ripley/University of Oxford, Tel: +44 1865 272861 (self)

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