Re: [R] Reading big files in chunks-ff package

2012-04-07 Thread Mav
Dear Jan,
Thank you for your answers. They are very useful. I will try the LaF
package.
Cheers,

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Re: [R] Reading big files in chunks-ff package

2012-03-25 Thread Mav
Thank you Jan

My problem is the following:
For instance, I have 2 files with different number of rows (15 million and 8
million of rows each).
I would like to read the first one in chunks of 5 million each. However
between the first and second chunk, I would like to analyze those first 5
million of rows, write the analysis in a new csv and then proceed to read
and analyze the second chunk and so on until the third chunk. With the
second file, I would like to do the same...read the first chunk, analyze it
and continue to read the second and analyze it.

Basically my problem is that I manage to read the filesbut with so many
rows...I cannot do any analyses (even filtering the rows) because of the RAM
restrictions.

Sorry if is still not clear.

Thank you

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[R] Reading big files in chunks-ff package

2012-03-24 Thread Mav
Hello!
A question about reading large CSV files

I need to analyse several files with  sizes larger than 3 GB. Those files
have more than 10million rows (and up to 25 million) and 9 columns. Since I
don´t have a large RAM memory,  I think that the ff package can really help
me. I am trying to use read.csv.ffdf but I have some questions:

How can I read the files in several chunks…with an automatic way of
calculating the number of rows to include in each chunk? (my problem is that
the files have different number of rows)

For instance…. I have used
read.csv.ffdf(NULL, “file.csv”, sep=|, dec=.,header = T,row.names =
NULL,colClasses = c(rep(integer, 3), rep(integer, 10), rep(integer,
6)))
 But with this way I am reading the whole fileI would prefer to read it
in chunksbut I don´t know  how to read it in chunks

I have read the ff documentation but I am not good with R!
 
Thanks in advance!

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