search for: boshao

...f this column are redundant. Or sometimes, to have a look at the rows that the elements of this column are redundant is also important. I guess it boils down to throw out the index of the redundant elements.   With millions of rows, how can I efficiently perform the task?   Thank you in advance.   Boshao [[alternative HTML version deleted]]

...to fit a Weibull model using R, you are my savior for my project. The hazard ramda is specified as t^alpha * (1+a*dose*exp(-b*dose)). Or, can we modify the Cox model to capture the proportional part above? Here t is the survial time, dose is a subject received in a exposed group. Thank you a lot. Boshao ____________________________________________________________________________________ Looking for last minute shopping deals?

...ues of grid point. It works well. Also, you can get the correct answer of log(1e-12). My questions are: What is the precision of a variable in R? How to specify the constraint interval of parameters in nlm? I tried lower, upper, it doesn't work. any advice on MLE is appreciated. Thank you. Boshao

Dear Helpers:   I spend more than half a day to solve this problem in R:   Let x be a vector of a string of 0s and 1s, such as x<-c(0,0,1,1,0,0,0,0,1,1,0,0,0,0). It can be a very long vector. How to sub vectors of 0s? In the above example, I would like get the vectors (0,0), (0,0,0,0), (0,0,0,0). I can use which(x==0) to get the index of the 0 elements, but I don't know how to get the

...va(lm.D9 <- lm(weight ~ group)) lm.D90 <- lm(weight ~ group - 1) # omitting intercept What I am doing is let the variable name "group" stored in a vector, say, g <- "group". The question is how to strip the quotation marks when we call lm( ) through g? Thank you all. Boshao ____________________________________________________________________________________ Never miss a thing. Make Yahoo your home page.