[R] Subset a data frame with specific date

Tue Jan 14 08:47:23 CET 2020

Thank you Bert.
And yes another topic to study.

On Tue, Jan 14, 2020 at 4:10 PM Bert Gunter <bgunter.4567 using gmail.com> wrote:
>
> That's fine, but do note that the which() function is wholly unnecessary in your last line as R allows logical indexing. Perhaps another topic you need to study.
>
> -- Bert
>
>
>
> On Mon, Jan 13, 2020 at 10:56 PM ani jaya <gaaauul using gmail.com> wrote:
>>
>> Dear Jeff and Bert,
>>
>> Thank you very much for your correction and explanation.
>> And yes, I need to study about date format more.
>> Sorry for HTML mail, don't realize.
>>
>> I was able to subset the data that I want.
>>
>> mjo30<-read.table("rmm.txt", header=FALSE, skip=4234, nrows=10957)
>> mjo30$V8<-NULL
>> names(mjo30)<-c("year","month","day", "rmm1","rmm2","phase","amp")
>> mjo3<-as.Date(with(mjo30,paste(year,month, day, sep="-")),"%Y-%m-%d")
>> mjo<-mjo30[which(mjo3%in%date),]
>>
>> head(mjo)
>>      year month day      rmm1      rmm2 phase      amp
>> 115  1986     4  25 -0.319090 -0.363030     2 0.483332
>> 526  1987     6  10  1.662870  0.291632     5 1.688250
>> 977  1988     9   3 -0.604950 -0.299850     1 0.675181
>> 1374 1989    10   5  0.972298 -0.461030     4 1.076060
>> 1760 1990    10  26 -1.183110 -1.589810     2 1.981730
>> 1953 1991     5   7 -0.317180  0.953061     7 1.004450
>>
>>
>> Best,
>> Ani
>>
>>
>> On Tue, Jan 14, 2020 at 3:20 PM Jeff Newmiller <jdnewmil using dcn.davis.ca.us> wrote:
>> >
>> > The dput function is for re-creating an R object in another R workspace, so it uses fundamental base types to define objects. A Date is really the number of days since a specific date (typically 1970-01-01) that get converted to look like dates whenever you display or print them, so what you are seiing are those numbers. If we enter the R code returned by dput into our R session we will be able to see the dates.
>> >
>> > Your mjo30 table seems to call the day of the month the "date"... which is confusing. I would combine those three columns into one like
>> >
>> > mjo30$Dt <- as.Date( ISOdate( mjo30$year, mjo30$month, mjo30$date ) )
>> >
>> > You could then use indexing
>> >
>> > mjo30[ date[1] == mjo30$Dt, ]
>> >
>> > or
>> >
>> > mjo30[ mjo30$Dt %in% date, ]
>> >
>> > but the subset function would not work in this case because you have two different objects (a column in mjo30 and a vector in your global environment) both referred to as 'date'.
>> >
>> > On January 13, 2020 8:53:38 PM PST, ani jaya <gaaauul using gmail.com> wrote:
>> > >Good morning R-Help,
>> > >
>> > >I have a dataframe with 7 columns and 10000+ rows. I want to
>> > >subset/extract
>> > >those data frame with specific date (not in order). Here the head of my
>> > >data frame:
>> > >
>> > >head(mjo30)  year month date      rmm1     rmm2 phase     amp
>> > >1 1986     1    1 -0.326480 -1.55895     2 1.59277
>> > >2 1986     1    2 -0.417700 -1.82689     2 1.87403
>> > >3 1986     1    3  0.032915 -2.40150     3 2.40172
>> > >4 1986     1    4  0.492743 -2.49216     3 2.54041
>> > >5 1986     1    5  0.585106 -2.76866     3 2.82981
>> > >6 1986     1    6  0.665013 -3.13883     3 3.20851
>> > >
>> > >and here my specific date:
>> > >> date [1] "1986-04-25" "1987-06-10" "1988-09-03" "1989-10-05"
>> > >"1990-10-26" "1991-05-07" "1992-11-19" "1993-01-23" "1994-12-04"
>> > >[10] "1995-05-11" "1996-10-04" "1997-04-29" "1998-04-08" "1999-01-16"
>> > >"2000-08-01" "2001-10-02" "2002-05-08" "2003-04-01"
>> > >[19] "2004-05-07" "2005-09-02" "2006-12-30" "2007-09-03" "2008-10-24"
>> > >"2009-11-14" "2010-07-05" "2011-04-30" "2012-05-21"
>> > >[28] "2013-04-07" "2014-05-07" "2015-07-26"
>> > >
>> > >And also I was confused when I dput my date, it show like this:
>> > >> dput(date)structure(c(5958, 6369, 6820, 7217, 7603, 7796, 8358, 8423,
>> > >9103,
>> > >9261, 9773, 9980, 10324, 10607, 11170, 11597, 11815, 12143, 12545,
>> > >13028, 13512, 13759, 14176, 14562, 14795, 15094, 15481, 15802,
>> > >16197, 16642), class = "Date")
>> > >
>> > >what is that mean? I mean why it is not recall the dates but some
>> > >values (5958,6369,7217,..)?
>> > >
>> > >Any comment and recommendation is appreciate.  Thank you.
>> > >
>> > >Best,
>> > >
>> > >Ani
>> > >
>> > >       [[alternative HTML version deleted]]
>> > >
>> > >______________________________________________
>> > >R-help using 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.
>> >
>> > --
>> > Sent from my phone. Please excuse my brevity.
>>
>> ______________________________________________
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>> and provide commented, minimal, self-contained, reproducible code.