R help - Oct 2018 - "logical indexing, " [was] match() question or needle haystack problem for a data.frame

I suggest you spend a bit of time with an R tutorial or two and, in
particular learn about "logical indexing," as this basic R construct
seems
to be mysterious to you.

Cheers,
Bert




On Mon, Oct 22, 2018 at 8:22 AM Knut Krueger <rhelp at krueger-family.de>
wrote:
> Am 22.10.18 um 17:01 schrieb Eric Berger:
> > v <- match(Mydata$DATA1, needles, nomatch=NA)
> >  > found <- Mydata[ !is.na <http://is.na>(v), ]
> >  > missing <- Mdata[ is.na <http://is.na>(v), ]
>
> Thank you it is working, additionally as Bert suggested, it seems that
>
> Mydata[Mydata$DATA1 %in% needles,]
>
> is doing the same.
>
> Kind Regards Knut
>
> ______________________________________________
> 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.
>
	[[alternative HTML version deleted]]

Am 22.10.18 um 18:02 schrieb Bert Gunter:
> I suggest you spend a bit of time with an R tutorial or two and, in 
> particular learn about "logical indexing," as this basic R
construct
> seems to be mysterious to you.
Hi Bert,

especially the "match" help area is a little bit confusing.

And additional using a couple of programming languages with different 
logical operators and different syntax is misleading me sometimes to the 
wrong direction...

So the logic operations itself are not mysterious ;-)  but the 
translation to R.
And thank's a lot to give me the keyword to find for what I am was 
looking for: logical indexing.

I can not count the sites where I was looking to solve my problem .. 
with the wrong keywords ... :-)

Kind Regards Knut

Hi Bert,
another question for indexing
1. is there a good manual  for indexing

2.  is it possible to get !%in%
f.e
x
=data.frame("A"=c(1:5),"C"=c("A","B","C","D","E"))
y =data.frame("B"=c(1,3,5))
test = x[x$A %in% y$B,]
test = x[x$A %in% y$B,]

test
A C
1 1 A
3 3 C
5 5 E


means: the result where I am looking for is:
test
A C
2 2 B
4 4 D

no problem with a loop but in a short way I do not find a solution

Kind Regards Knut

> On 25 Oct 2018, at 16:06 , Knut Krueger <rhelp at krueger-family.de>
wrote:
> 
> Hi Bert,
> another question for indexing
> 1. is there a good manual  for indexing
?Extract is at least authoritative....
> 
> 2.  is it possible to get !%in%
> f.e

Yes: x[!(x$A %in% y$B),]

-pd
> x
=data.frame("A"=c(1:5),"C"=c("A","B","C","D","E"))
> y =data.frame("B"=c(1,3,5))
> test = x[x$A %in% y$B,]
> test = x[x$A %in% y$B,]
> 
> test
> A C
> 1 1 A
> 3 3 C
> 5 5 E
> 
> 
> means: the result where I am looking for is:
> test
> A C
> 2 2 B
> 4 4 D
> 
> no problem with a loop but in a short way I do not find a solution
> 
> Kind Regards Knut
> 
> ______________________________________________
> 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.
-- 
Peter Dalgaard, Professor,
Center for Statistics, Copenhagen Business School
Solbjerg Plads 3, 2000 Frederiksberg, Denmark
Phone: (+45)38153501
Office: A 4.23
Email: pd.mes at cbs.dk  Priv: PDalgd at gmail.com

Hello,

2. x[!x$A %in% y$B, ]

1.
An Introduction to R, file R-into.pdf in your docs folder.
http://www.cookbook-r.com/Basics/Indexing_into_a_data_structure/


Hope this helps,

Rui Barradas

?s 15:06 de 25/10/2018, Knut Krueger escreveu:
> Hi Bert,
> another question for indexing
> 1. is there a good manual? for indexing
> 
> 2.? is it possible to get !%in%
> f.e
> x
=data.frame("A"=c(1:5),"C"=c("A","B","C","D","E"))
> y =data.frame("B"=c(1,3,5))
> test = x[x$A %in% y$B,]
> test = x[x$A %in% y$B,]
> 
> test
> A C
> 1 1 A
> 3 3 C
> 5 5 E
> 
> 
> means: the result where I am looking for is:
> test
> A C
> 2 2 B
> 4 4 D
> 
> no problem with a loop but in a short way I do not find a solution
> 
> Kind Regards Knut
> 
> ______________________________________________
> 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.

Dear Knut,
> -----Original Message-----
> From: R-help [mailto:r-help-bounces at r-project.org] On Behalf Of Knut
> Krueger
> Sent: Friday, October 26, 2018 2:29 AM
> To: r-help mailing list <r-help at r-project.org>
> Subject: Re: [R] "logical indexing, " [was] match() question or
needle haystack
> problem for a data.frame
> 
> Am 25.10.18 um 16:13 schrieb peter dalgaard:
> >
> >
> > Yes: x[!(x$A %in% y$B),]
> 
> Ok thats in my opinion a little workaround
Not a work-around but a solution. That is, one can't expect to find an
existing function for every problem.
> why?:
> 
> There is an
> = and !
Actually == and !
> < and >
> 
> 
> means the opposite is available between terms.
> 
> why is there f.e no %!in%, %notin%  or !%in%
> 
> This would be more intuitive.
If you feel strongly about this, it's not hard to supply it:
> `%!in%` <- function(x, y) !(x %in% y)
> (1:4) %in% (2*1:4)
[1] FALSE  TRUE FALSE  TRUE
> (1:4) %!in% (2*1:4)
[1]  TRUE FALSE  TRUE FALSE

Best,
 John

-----------------------------------------------------------------
John Fox
Professor Emeritus
McMaster University
Hamilton, Ontario, Canada
Web: https://socialsciences.mcmaster.ca/jfox/

> 
> Kind regards Knut
> 
> ______________________________________________
> 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.