Hi Marion,
as stated in the help file ?apply coerces a data.frame object into an
array. Since an array has only one type of data, this coercion turns all
your variables into strings (because this data type can hold all
information given without loss).
If it happens that your data.frame consists only of numeric variables,
then this type suffices for the array as well, and things like sum or
mean can be applied row/columnwise.
btw:
apply(mydataframe,2,function(x)sum(x))
doesn't work either (for the same reason).
Cheers
Am 19.07.2012 11:48, schrieb Marion Wenty:
> Dear people,
>
> I am including an example of a dataframe:
>
> mydataframe<-data.frame(X=c(1:4),total_bill=c(16.99,10.34,21.01,23.68),tip=c(1.01,1.66,3.50,3.31),sex=c("Male","Male","Male","Female"))
>
> When I use the sapply function getting the information about the factors
> works:
>
> sapply(mydataframe,function(x)is.factor(x))
>
> X total_bill tip sex
> FALSE FALSE FALSE TRUE
>
>
> But if I use the apply function it doesn't work:
>
> apply(mydataframe,2,function(x)is.factor(x))
>
> X total_bill tip sex
> FALSE FALSE FALSE FALSE
>
>
> I don't understand why, because I have used the apply function for
> dataframes before e.g. using sum(x) instead of is.factor(x) and it did work.
>
> Could anyone help me with this?
>
> Thank you very much for your help in advance!
>
> Marion
>
> [[alternative HTML version deleted]]
>
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