type conversion from LogicalVector to NumericVector

[liyi-1989]

Can we do type conversion from True to 1, and False to 0? Met this problem when doing multiplication of a indicator function of a vector. Thanks!

[eddelbuettel]

Do you when like this:

R> library(Rcpp)
R> cppFunction('double mysum(LogicalVector x) { return(sum(x)); }')
R> mysum(c(rep(TRUE,3), rep(FALSE, 2), rep(TRUE, 3)))
[1] 6
R> 

Please use the rcpp-devel list for simple questions instead of this issue tracking system. Thanks.

There may always be type conversions 'missing' ie something the compiler does not get quite right by wrap() and as<>() can help you.

[liyi-1989]

Thanks! In your example, I want to do element-wise operation of that LogicalVector: like (True,False,True)*1.5=(1.5,0,1.5) which is a NumericalVector.

I actually want to calculate a simple box kernel of a NumericalVector x, which is (abs(x)<1) /2.0, but the LogicalVector cannot multiplied by a double, and thus cannot get a NumericalVector.

I will switch to the rcpp-devel list. Thanks you so much for your help!

[liyi-1989]

Thanks! It works when using wrap(), though a little bit indirect.
NumericVector r=wrap(abs(x)<=1); return r/2.0;

Thank you very much!

[eddelbuettel]

It's tricky as there are so many permutation of type and ops -- I guess you did find we do not have LogicalVector ops double. I have use (Rcpp)Armadillo for related things -- here you would have started without a boolean vector (but rather unsigned int) because Armadillo is more focused on all things numbers. But then it has the matching ops...

[eddelbuettel]

FYI here is one way of doing logical ops on Armadillo vectors. You may find more luck over there.

[liyi-1989]

Thanks @eddelbuettel for your help! I will check the post.