[R] Reading a csv file row by row
martin.becker at mx.uni-saarland.de
Fri Apr 6 11:23:39 CEST 2007
readLines (which is mentioned in the "See also" section of ?scan with
the hint "to read a file a line at a time") should work.
Yuchen Luo schrieb:
> 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 will be read.
> I tried to replicate such row-by-row reading in R.I use scan( ) to do so
> with the "skip= xxx " option. It takes only seconds when the number of the
> rows is within 1000. However, it takes hours to read 10000 rows. I think it
> is because every time R reads, it needs to start from the first row of the
> file and count xxx rows to find the row it needs to read. Therefore, it
> takes more time for R to locate the row it needs to read.
> Is there a solution to this problem?
> Your help will be highly appreciated!
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> and provide commented, minimal, self-contained, reproducible code.
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