sorry also error in the URL should be…. >> http://www.truefx.com/dev/data/2013/MAY-2013/AUDUSD-2013-05.zip On 5 Jul 2013, at 15:24, Hideyoshi Maeda <[email protected]> wrote:
> One other thought I had was perhaps it might be better to just preallocate > column names if need be and then read in? > > > On 5 Jul 2013, at 14:55, Hideyoshi Maeda <[email protected]> wrote: > >> Hi, >> >> I would like to be able to skip a column that is read into R via fread. But >> the csv I am reading in, has no column headers…which appears to be a problem >> for fread…is there a way to just specify that I don't want specific columns? >> >> To give an example… >> >> I downloaded the data from the following URL >> >> http://www.truefx.com/dev/data/2013/JUNE-2013/AUDUSD-2013-05.zip >> >> unzipped it… >> >> and read the csv into R using fread and it has pretty much the same file >> name just with the csv extension. >> >>> system.time(pp <- fread("AUDUSD-2013-05.csv",sep=",")) >> user system elapsed >> 16.427 0.257 16.682 >>> head(pp) >> V1 V2 V3 V4 >> 1: AUD/USD 20130501 00:00:04.728 1.03693 1.03721 >> 2: AUD/USD 20130501 00:00:21.540 1.03695 1.03721 >> 3: AUD/USD 20130501 00:00:33.789 1.03694 1.03721 >> 4: AUD/USD 20130501 00:00:37.499 1.03692 1.03724 >> 5: AUD/USD 20130501 00:00:37.524 1.03697 1.03719 >> 6: AUD/USD 20130501 00:00:39.789 1.03697 1.03717 >>> str(pp) >> Classes ‘data.table’ and 'data.frame': 4060762 obs. of 4 variables: >> $ V1: chr "AUD/USD" "AUD/USD" "AUD/USD" "AUD/USD" ... >> $ V2: chr "20130501 00:00:04.728" "20130501 00:00:21.540" "20130501 >> 00:00:33.789" "20130501 00:00:37.499" ... >> $ V3: num 1.04 1.04 1.04 1.04 1.04 ... >> $ V4: num 1.04 1.04 1.04 1.04 1.04 ... >> - attr(*, ".internal.selfref")=<externalptr> >> >> I tried using the new(ish) colClasses or skip arguments to ignore the fact >> that the first column is all the same…and is unnecessary. >> >> but doing: >> >> pp1 <- fread("AUDUSD-2013-05.csv",sep=",",skip=1) >> >> doesn't omit the reading in of the first column >> >> and using colClasses leads to the following error >> >> pp1 <- >> fread("AUDUSD-2013-05.csv",sep=",",colClasses=list(NULL,"character","numeric","numeric")) >> >> Error in fread("AUDUSD-2013-05.csv", sep = ",", colClasses = list(NULL, : >> colClasses is type list but has no names >> >> Are there any suggestions to be able to speed up the reading in of data by >> omitting the first column? >> >> Also perhaps a bit much to ask, but is it possible to directly read a zip >> file rather than unzipping it first and then reading in the csv? >> >> Oh and if it wasn't clear I'm using v1.8.9 >> >> As always, thanks for all of your help, effort and advice in advance. >> >> HLM > _______________________________________________ datatable-help mailing list [email protected] https://lists.r-forge.r-project.org/cgi-bin/mailman/listinfo/datatable-help
