CODEWITHSUNDEEP
r
dgg32
dgg32

Reputation: 1457

Does R have 'dict' as in python or 'map' as in c++ do?

I am new to R programming. After checking some tutorial I picked up most things I needed, but one thing is still missing: the data structure map.

Does everybody know if R has dict? In which I can store (key, value) pairs?

Thanks!!

Upvotes: 10

Views: 3430

Answers (5)

ctbrown
ctbrown

Reputation: 2361

The hash package as aforementioned does add a little overhead but does provide a flexible, intuitive methods for accessing the map/hash/dictionary. It should be very easy for users from another language to grok it.

A list is the best solution if the list has a small number of elements. (<200 or so).

An environment is best to use if you absolutely cannot tolerate a little overhead AND you do not want the flexible, intuitive methods.

The hash package is the best in most situations.

C-

Upvotes: 0

Richie Cotton
Richie Cotton

Reputation: 121127

Since array/vector elements can be named, you get some of the properties of a map/dictionary builtin.

x <- c(apple = 1, banana = 99, "oranges and lemons" = 33)
x["apple"]
x[c("bananas", "oranges and lemons")]
x[x == 99]

(If your values are of different types, then you need to use a list instead of a vector.)

Upvotes: 3

Andrew Redd
Andrew Redd

Reputation: 4692

Environments are also a candidate, and in many cases the best option.

e<-new.env(hash=T)
e$a<-1
e$b<-2

R> e$a
[1] 1

The disadvantage of a list is that it is a linear search.

Upvotes: 5

David Heffernan
David Heffernan

Reputation: 613382

Yes it does and it is called list.

> x <- list(a=1, b="foo", c=c(1,1,2,3,5))
> x
$a
[1] 1

$b
[1] "foo"

$c
[1] 1 1 2 3 5

In Python it is called dict, for what it's worth.

Upvotes: 9

Karsten W.
Karsten W.

Reputation: 18500

There is the hash package..

Upvotes: 3

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