[R] like apply(x,1,sum), but using multiplication?

Sundar Dorai-Raj sundar.dorai-raj at pdf.com
Mon May 7 20:33:42 CEST 2007

Jose Quesada said the following on 5/7/2007 11:25 AM:
> Hi,
> I need to multiply all columns in a matrix so something like  
> apply(x,2,sum), but using multiplication should do.
> I have tried apply(x,2,"*")
> I know this must be trivial, but I get:
> Error in FUN(newX[, i], ...) : invalid unary operator
> The help for apply states that unary operators must be quoted. I tried  
> single quotes too, with the same results.
> Thanks,
> -Jose

Try: apply(x,2,prod)



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