Hoping for a little insight into how to make sure I have R running as efficiently as possible.
Suppose I have a data frame, A, with n rows and m columns, where col1 is a date time stamp. Also suppose that when this data is imported (from a csv or SQL), that the data is already sorted such that the time stamp in col1 is in ascending (or descending) order. If I then wanted to select only the rows of A where col1 <= a certain time, I am wondering if R has to read through the entirety of col1 to select those rows (all n of them). Is it possible for R to recognize (or somehow be told) that these rows are already in order, thus allowing the computation could be completed in ~log(n) row reads instead? Thanks! ______________________________________________ R-help@r-project.org mailing list https://stat.ethz.ch/mailman/listinfo/r-help PLEASE do read the posting guide http://www.R-project.org/posting-guide.html and provide commented, minimal, self-contained, reproducible code.
