[R] Reading extremly large comma separated files?

S Ellison S.Ellison at LGCGroup.com
Wed Dec 19 12:45:19 CET 2012


> Are there any tricks or wise suggestions on how to import 
> huge comma separated files into R? We have used the ordinary 
> "read syntax" but it takes forever....

One potential time- and memory saver is to specify the class of each column using colClasses in read.table.

For a large data set (800 000 rows) on Windows I also found it quicker and more reliable to import the data into a MySQL database and then use ODBC  to read the data into R than to use read.table on the raw data - but that was in part because I hada bit of trouble with the file encoding and MySQL/ODBC sidestepped the issue. 

S Ellison 

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