Here is another approach that uses only the default packages: > onecar <- mtcars[10,] > w <- which(duplicated(rbind(mtcars,onecar), fromLast = TRUE)) > w [1] 10 > mtcars.subset <- mtcars[-w,] > > > threecars <- mtcars[c(1,10,15),] > w <- which(duplicated(rbind(mtcars,threecars), fromLast=TRUE)) > w [1] 1 10 15 > mtcars.subset <- mtcars[-w, ]
This works with a subset of 1, or more than 1, but could cause problems if you have duplicate rows in your original data frame. If you are willing to use a non-default package then there are many possibilities. The anti_join function from the dplyr package has already been mentioned, but the setdiff function from dplyr would also work here and would be a little simpler for your example: > library(dplyr) > mtcars.subset2 <- setdiff(mtcars,threecars) > identical(as.list(mtcars.subset), as.list(mtcars.subset2)) [1] TRUE The as.list function above was to remove some attributes that were different between the outputs. On Thu, Jan 3, 2019 at 10:59 AM Benoit Galarneau <benoit.galarn...@polymtl.ca> wrote: > > Thanks for the feedback. > Point taken about the data.table package, I will take a look for sure. > As I am new to the R programming, I'm exploring with the default > libraries as a start. > > I have various options that works like this one: > > topCard <- deck[1,] > #Remove card from deck using row name > deck <- deck[!rownames(deck) %in% row.names(topCard),] > > Is it recommended/safe/good practice to work on items using the item names? > > Benoit > > Jeff Newmiller <jdnew...@dcn.davis.ca.us> a écrit : > > >> In my programmer's head, something similar to this should "work": ... > >> deck[aCard] > > > > There are some people who agree with you... see the data.table > > package, which can be made to behave like this. > > > > Keep in mind that the aCard data frame in general may have a > > different set of column names or more than one row. (I would be > > concerned that the logic of your application was inefficiently > > designed if `deck` actually has the same columns as `aCard` as in > > your example.) Others have pointed out that data frames are > > typically combined using the merge function, which allows matching > > columns to be specified very flexibly. > > > > > > On January 3, 2019 6:50:22 AM PST, Benoit Galarneau > > <benoit.galarn...@polymtl.ca> wrote: > >> Hi everyone, > >> I'm new to the R world. > >> Probably a newbie question but I am stuck with some concept with data > >> frame. > >> I am following some examples in the "Hands-On Programming with R". > >> > >> In short, how can I access/filter items in a data frame using a > >> variable. > >> > >> One example consists of manipulating elements from a deck of card: > >> > >>> deck > >> face suit value > >> 1 king spades 13 > >> 2 queen spades 12 > >> 3 jack spades 11 > >> 4 ten spades 10 > >> etc. > >> > >> Let's say I want to remove or filter out the first card. I know I > >> could do deck[-1]. > >> > >> But let's say I have: topCard <- deck[1,] > >> > >> topCard is then a list of 3 elements > >>> topCard > >> face suit value > >> 1 king spades 13 > >> > >> My question is the following, how can I remove or filter out the deck > >> using the topCard variable. > >> > >> In my programmer's head, something similar to this should "work": > >>> deck[10,] > >> face suit value > >> 10 four spades 4 > >>> aCard <- deck[10,] > >>> aCard > >> face suit value > >> 10 four spades 4 > >>> deck[aCard] > >> Error in `[.default`(deck, aCard) : invalid subscript type 'list' > >> > >> Wihout having to specify all elements in the logical tests. > >> > >> deck[deck$face == aCard$face & deck$suit == aCard$suit & deck$value == > >> > >> aCard$value,] > >> face suit value > >> 10 four spades 4 > >> > >> ______________________________________________ > >> R-help@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. > > ______________________________________________ > R-help@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. -- Gregory (Greg) L. Snow Ph.D. 538...@gmail.com ______________________________________________ R-help@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.
