[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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