Hi Benoit,
You can select rows from deck matched in aCard using
merge(deck, aCard)
Selecting rows that don't match is bit more difficult. You could do
something like
isin <- apply(mapply(function(x, y) x %in% y, deck, topCard),
1,
all)
deck[!isin, ]
perhaps.
Alternatively, you can use anti_join from the dplyr package:
library(dplyr)
anti_join(deck, topCard)
Best,
Ista
On Thu, Jan 3, 2019 at 10:38 AM 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
>
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