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I have a new device that takes measurements anywhere from every second, to every 15 minutes (depending on changes). The matrix has a date, time and Y column (Y is the measurement). For three days it is 25,000 rows. How do I average the measurements by every 30 minutes so my matrix is 48 rows per day? I have been working on this and cannot figure out a simple method. Any ideas? Thank you. ----- In

Hi, my friends. When a data file is large, loading the whole file into the memory all together is not feasible. A feasible way is to read one row, process it, store the result, and read the next row. In Fortran, by default, the 'read' command reads one line of a file, which is convenient, and when the same 'read' command is executed the next time, the next row of the same file

Dear Listers: I have a couple of data frames to report and each corresponds to different condtions, e.g. conditions=c(10, 15, 20, 25). In this examples, four data frames need to be exported in a "pretty" report. I knew Perl has some module for exporting data to Excel and after googling, I found R does not. So I am wondering if there is a package in R for generating good reports. I