Hi,
Ah yes, haven't hooked up the sep override yet, apologies, will fix.
Maybe setting autostart to the row number of the header row (probably
1)
might work.
Thanks,
Matthew
On 24.12.2012 11:08, Hideyoshi Maeda wrote:
oups…forgot to add the output from the verbose part…here it is...
Detected eol as \r\n (CRLF) in that order, the Windows standard.
Starting format detection on line 30 (the last non blank line in the
first 30)
Detected sep as '/' and 3 columns
Type codes: 003
Found first row with 3 fields occuring on line 1 (either column names
or first row of data)
The first data row has some non character fields. Treating as a data
row and using default column names.
Count of eol after pos: 1143699
Subtracted 1 for last eol and any trailing empty lines, leaving
1143698 data rows
0.153s ( 21%) Memory map (quicker if you rerun)
0.000s ( 0%) Format detection
0.095s ( 13%) Count rows (wc -l)
0.001s ( 0%) Allocation of 1143698x3 result (xMB) in RAM
0.480s ( 66%) Reading data
0.000s ( 0%) Bumping column type midread and coercing data
already read
0.002s ( 0%) Changing na.strings to NA
0.731s Total
On 24 Dec 2012, at 11:04, Hideyoshi Maeda <[email protected]>
wrote:
Hi Matthew,
I am using the new `data.table` `fread()` function to read my csv
files, which has the format as follows when using the read.csv
function
Date.and.Time Open High Low Close Volume
1 2007/01/01 22:51:00 5683 5683 5673 5673 64
2 2007/01/01 22:52:00 5675 5676 5674 5674 17
3 2007/01/01 22:53:00 5674 5674 5673 5674 42
The value of the first column is all of: `2007/01/01 22:53:00`, the
next 5 columns are separated with commas.
but when reading the same file using fread i get the following
output
V1 V2 V3
1 2007 1 01 22:51:00,5683.00,5683.00,5673.00,5673.00,64
2 2007 1 01 22:52:00,5675.00,5676.00,5674.00,5674.00,17
3 2007 1 01 22:53:00,5674.00,5674.00,5673.00,5674.00,42
This is because the autodetect is using the "/" as a separator...
I tried overriding this using the `sep=","` argument but this does
not seem to be used in the function anywhere.
Furthremore when using verbose I get the following output, which
suggests that I was right in thinking that "/" is used as a separator
rather than ",".
Is there any way to fix this, so that it correctly reads all 6
columns separately?
Thanks
HLM
On 21 Dec 2012, at 18:28, Matthew Dowle <[email protected]>
wrote:
Hi datatablers,
Feedback and bug reports much appreciated :
=====
New function fread(), a fast and friendly file reader.
* header, skip, nrows, sep and colClasses are all auto detected.
* integers>2^31 are detected and read natively as bit64::integer64.
* accepts filenames, URLs and "A,B\n1,2\n3,4" directly
* new implementation entirely in C
* with a 50MB .csv, 1 million rows x 6 columns :
read.csv("test.csv") # 30-60
sec
read.table("test.csv",<all known tricks, known nrows>) # 10
sec
fread("test.csv") # 3
sec
* airline data: 658MB csv (7 million rows x 29 columns)
read.table("2008.csv",<all known tricks, known nrows>) # 360
sec
fread("2008.csv") # 50
sec
See ?fread. Many thanks to Chris Neff and Garrett See for ideas,
discussions and beta testing.
=====
1.8.7 is passing checks on Unix and Windows (but not Mac yet) :
install.packages("data.table",
repos="http://R-Forge.R-project.org";)
require(data.table)
?fread
fread("your biggest baddest file")
Oddly, R-Forge appears to be compiling Win64 with -O2 optimization
rather
than -O3 (but -O3 on Win32 ok), so speedups might not be as great
on Win64
until that can be resolved on R-Forge, unless you compile yourself.
-O3
has some optimizations that fread may benefit from. But interested
to hear.
Seasons greatings!
Matthew
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