[R] Data.Frame Multiplication

[Achim Zeileis]

Christian Schulz wrote:
> 
> Have got  any  R-proffessional  a starting point for me
> how i can write me a function which multiply every column with
> every other column in the data.frame - indenpendent from the dim's .

You could start from a function that multiplies a chosen column `col' of
a data.frame `df' with the following columns

  multiply <- function(df, col) df[,col] * df[,-(1:col), drop = FALSE]

and then apply that to your data.frame `mydata' like

  sapply(1:(ncol(mydata) - 1), function(x) multiply(mydata, x))

For the latter part, there might be a better way to do that depending on
how you want to format the output...
Z 

> Thanks in advance
> regards,Christian
> 
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