vector angle
Evan Zane Macosko wrote:
Hi everyone, I'm translating into R some programs I worked through in Matlab to calculate the angle between two vectors (very large--like 6200 rows in each vector). In Matlab, I used a series of nested for loops, because I was calculating the angles between many pairs of vectors. I know for loops are not desirable in R code, so I was wondering if anyone could recommend a faster way to complete this task. Also, I have NAs in my vectors--I've had trouble performing various operations on my vectors in R because of these NAs. Any advice on this would be greatly appreciated.
As far as I know, the use of apply (sapply and lapply) would make things run faster than 'for' loops. About the NAs, you may want to ignore the vectors which have a NA coordinate, or may be do something else... to have a foot in this, you may try the help for the functions 'is.na' and 'na.action'. I hope it helps, Laurent -- Laurent Gautier CBS, Building 208, DTU PhD. Student D-2800 Lyngby,Denmark tel: +45 45 25 24 85 http://www.cbs.dtu.dk/laurent -------------- next part -------------- An HTML attachment was scrubbed... URL: https://stat.ethz.ch/pipermail/r-help/attachments/20010717/a5a3487b/attachment.html