Reposting in hope of a reply.
On Tue, Apr 24, 2012 at 1:12 AM, Shivam <shivamsi...@gmail.com> wrote:
> Thanks for the quick response. It works for an individual dataframe, but I
> have many dataframes. This is the code so far
>
> fnames = list.files(path = getwd())
> for (i in 1:length(fnames)){
> assign(paste("file",i,sep=""),read.csv.sql(fnames[i], sql = "select * from
> file where V3 == 'XXX' and V5=='YYY'",header = FALSE, sep= '|', eol = "\n"))
> }
>
> This generates dataframes named as as file1,file2,...,file250. Is there a
> way to do something like below within the same loop?
>
> file1$date = substr(fnames[1],1,8))
> file2$date = substr(fnames[2],1,8))
> .
> .
> file250$date = substr(fnames[250],1,8))
>
> assign(paste("file",i,sep="")$date doesnt work.
>
> Any help?
>
>
>
>
>
> On Tue, Apr 24, 2012 at 12:01 AM, MacQueen, Don <macque...@llnl.gov>wrote:
>
>> This little example might help.
>>
>> > foo <- data.frame(a=1:10, b=letters[1:0])
>> > foo
>> a b
>> 1 1 a
>> 2 2 a
>> 3 3 a
>> 4 4 a
>> 5 5 a
>> 6 6 a
>> 7 7 a
>> 8 8 a
>> 9 9 a
>> 10 10 a
>> > foo$date <- '20120423'
>> > foo
>> a b date
>> 1 1 a 20120423
>> 2 2 a 20120423
>> 3 3 a 20120423
>> 4 4 a 20120423
>> 5 5 a 20120423
>> 6 6 a 20120423
>> 7 7 a 20120423
>> 8 8 a 20120423
>> 9 9 a 20120423
>> 10 10 a 20120423
>>
>>
>> In other words, immediately after reading the data into a data frame, add
>> a date column as in the example. You'll have to extract the date from the
>> filename, of course.
>>
>> -Don
>>
>>
>> --
>> Don MacQueen
>>
>> Lawrence Livermore National Laboratory
>> 7000 East Ave., L-627
>> Livermore, CA 94550
>> 925-423-1062
>>
>>
>>
>>
>>
>> On 4/23/12 9:29 AM, "Shivam" <shivamsi...@gmail.com> wrote:
>>
>> >Hi,
>> >
>> >I am relatively new to R. Have scourged the help files and the www but
>> >havent been able to get a solution.
>> >
>> >I have around 250 csv files, one file for each date. They have columns of
>> >all types, numeric, string etc. The name of each file is the date in the
>> >form of 'yyyymmdd'. There is no column within the file which helps me
>> >identify the date on which the file was generated, only the filename has
>> >that info.
>> >
>> >I am selecting some data (using read.csv.sql) from each file and creating
>> >a
>> >dataset for each day. Ultimately I will combine all the datasets. I can
>> >accomplish the select and combine part, but after combining I wont have a
>> >record as to the date corresponding to the data.
>> >
>> >Hence I want to insert the filename as a column in the respective file to
>> >help me in identifying to what date each data row belongs to.
>> >
>> >Sorry for the long mail, but wanted to make myself clear. Any help would
>> >be
>> >greatly appreciated.
>> >
>> >Thanks in advance,
>> >Shivam
>> >
>> > [[alternative HTML version deleted]]
>> >
>> >______________________________________________
>> >R-help@r-project.org mailing list
>> >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.
>>
>>
>
>
> --
> *Victoria Concordia Crescit*
>
--
*Victoria Concordia Crescit*
[[alternative HTML version deleted]]
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