[R] Accessing Data Frame
Benoit Galarneau
benoit@g@l@rne@u @ending from polymtl@c@
Thu Jan 3 15:50:22 CET 2019
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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