Is there a dictionary functionality in R

Question

Is there a way to create a \"dictionary\" in R, such that it has pairs? Something to the effect of:

x=dictionary(c(\"Hi\",\"Why\",\"water\") , c(1,5,4))
x[\         


        

Answer 1

In that vectors, matrices, lists, etc. behave as "dictionaries" in R, you can do something like the following:

> (x <- structure(c(5,2),names=c("a","b"))) ## "dictionary"
a b 
5 2 
> (result <- outer(x,x,function(x1,x2) x1^2+x2))
   a  b
a 30 27
b  9  6
> result["b","a"]
[1] 9

If you wanted a table as you've shown in your example, just reshape your array...

> library(reshape)
> (dfr <- melt(result,varnames=c("x1","x2")))
  x1 x2 value
1  a  a    30
2  b  a     9
3  a  b    27
4  b  b     6
> transform(dfr,val1=x[x1],val2=x[x2])
  x1 x2 value val1 val2
1  a  a    30    5    5
2  b  a     9    2    5
3  a  b    27    5    2
4  b  b     6    2    2