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 = '
')
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