I am dealing with data frames that have thousands of columns and hundreds of thousands of rows and only need a few specific columns from the data. The data take various formats, but normally are tab-delimited.
I have written the following which is working as expected. However, because I�m so new at using sqldf(), just looking for some verification from users that this is in fact efficient and correct in the R-ish sense of the word and generalizable to larger data sets. Harold tmp <- data.frame(replicate(50, rnorm(10))) names(tmp) <- paste('item', 1:50, sep='') write.table(tmp, 'tmp.txt') read.csv.sql("tmp.txt", sql = "select item1, item2, item50 from file", sep = ' ') [[alternative HTML version deleted]]
______________________________________________ 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.