[R] fread transforms numbers

[Santosh]

Thanks so much for your suggestions! Will try them out!

Santosh

On Wed, Mar 22, 2017 at 12:17 PM, Matt Dowle <mattjdowle at gmail.com> wrote:

> Thanks Bill for cc.
>
> Santosh,
>
> I'm almost certain you don't have package bit64 installed.  When you do it
> works fine :
>
> > remove.packages("bit64")
> > data.table::fread("9876543210\n")
>               V1
> 1: 4.879661e-314
> > install.packages("bit64")
> > data.table::fread("9876543210\n")
>            V1
> 1: 9876543210
>
> News for data.table v1.10.2 on CRAN 31 Jan 2017 contained :
>
> * When fread() or print() see integer64 columns are present, bit64's
> namespace is now automatically loaded for convenience.
>
> However, when data.table loads the namespace there is a bug in this
> function :
>
> > data.table:::require_bit64
> function ()
> {
>     tt = try(requireNamespace("bit64", quietly = TRUE))
>     if (inherits(tt, "try-error"))
>         warning("Some columns are type 'integer64' but package bit64 is
> not installed. Those columns will print as strange looking floating point
> data. There is no need to reload the data. Simply install.packages('bit64')
> to obtain the integer64 print method and print the data again.")
> }
>
> The intent was to display that nice helpful message to you.   Due to this
> report, I can see now that I shouldn't have wrapped requireNamespace() with
> try() because  requireNamespace() returns TRUE or FALSE anyway. Even though
> requireNamespace() prints 'Failed with error' it doesn't actually throw an
> error.  I'll change data.table's function to the following :
>
> if (!requireNamespace("bit64", quietly = TRUE))
>     warning("Some columns ...")
>
> bit64 is correctly Suggests not Depends.   It's just unfortunate the
> intended message wasn't displayed.
>
> Santosh, in future please follow the data.table support guide here:
> https://github.com/Rdatatable/data.table/wiki/Support.  r-help is not
> supposed to be used for package support.  The main thing though is thanks
> for helping me find this bug.
>
> Thanks,
> Matt
>
>
> On Wed, Mar 22, 2017 at 10:22 AM, William Dunlap <wdunlap at tibco.com>
> wrote:
>
>> Here is a way to reproduce the problem:
>>   > data.table::fread("9876543210\n") # number bigger than 2^31-1
>>                 V1
>>   1: 4.879661e-314
>> and your work-around does fix things up
>>   > data.table::fread("9876543210\n", colClasses="numeric")
>>              V1
>>   1: 9876543210
>>
>> Bill Dunlap
>> TIBCO Software
>> wdunlap tibco.com
>>
>>
>> On Wed, Mar 22, 2017 at 9:58 AM, Jeff Newmiller
>> <jdnewmil at dcn.davis.ca.us> wrote:
>> > You failed to provide a reproducible example, and you posted HTML so
>> the quality of any answer will be limited by the quality of your question.
>> >
>> > My stab at your problem is that you should read ?fread, and in
>> particular should try using the colClasses argument.
>> > --
>> > Sent from my phone. Please excuse my brevity.
>> >
>> > On March 22, 2017 8:52:55 AM PDT, Santosh <santosh2005 at gmail.com>
>> wrote:
>> >>Hi
>> >>
>> >>I have been using "fread" utility of "data.table" packge .. on a
>> >>dataset of
>> >>about 20 million rows. It's a fantastic package to read datasets. Thank
>> >>you, Matt D.
>> >>
>> >>However, I am faced with a peculiar instance of  certain numbers in a
>> >>column being transformed.
>> >>
>> >>In the dataset, a column has values ranging from 1 to 9##########
>> >>(nchar(x)=11, e.g. 98765432109). After using "fread" to read the
>> >>dataset,
>> >>values in all the columns are displayed correctly upto the first 1000
>> >>rows.
>> >>If "fread" is applied for reading >1000 rows of  the total of 20Million
>> >>rows, the values in only this (column (having wide range of values) are
>> >>displayed as x.xxxxxxxe-3yy. (e.g. 3.5639877e-324)
>> >>
>> >>I tried reading all the columns as "character" and didn't help.
>> >>
>> >>Would highly appreciate your assistance!
>> >>
>> >>Thanks so much in advance.
>> >>
>> >>Best regards,
>> >>Santosh
>> >>
>> >>       [[alternative HTML version deleted]]
>> >>
>> >>______________________________________________
>> >>R-help at r-project.org mailing list -- To UNSUBSCRIBE and more, see
>> >>https://stat.ethz.ch/mailman/listinfo/r-help
>> >>PLEASE do read the posting guide
>> >>http://www.R-project.org/posting-guide.html
>> >>and provide commented, minimal, self-contained, reproducible code.
>> >
>> > ______________________________________________
>> > R-help at r-project.org mailing list -- To UNSUBSCRIBE and more, see
>> > https://stat.ethz.ch/mailman/listinfo/r-help
>> > PLEASE do read the posting guide http://www.R-project.org/posti
>> ng-guide.html
>> > and provide commented, minimal, self-contained, reproducible code.
>>
>
>

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