Vector class about datastructures HOT 5 OPEN

for []. you may overload the [.classname operator in R.

> x <- structure("test", class="testclass")
> "[.testclass" <- function(x, i)
+ stringi::stri_sub(x, i, length=1)
> x[1]
[1] "t"
> x[2]
[1] "e"

replacement version:

> "[<-.testclass" <- function(x, i, value) {
+ stringi::stri_sub(x, i, length=1) <- value
+ x
+ }
> x[1] <- ":P"
> x
[1] ":Pest"

vector of any R objects == list (in Rcpp, this will be std::vector<RObject>.

from datastructures.

Why do we use SEXP in stack and queue? Maybe we can also use RObject in stack and queue? Is it any difference?

from datastructures.

On 20.03.2015 09:38, Maciej Bartoszuk wrote:

Why do we use SEXP in stack and queue? Maybe we can also use RObject in
stack and queue? Is it any difference?

RObject is a thin wrapper around an underlying SEXP. When storing data
is concerned only , SEXP is better (more lightweight)

from datastructures.

Ok, I committed vector class in 1196208 .

Unfortunately, there are some issues in getting/setting one element, like at() or operator[].

Firstly, I tried as you said

"[.Vector" <- function(vec, i)
 {
    vector_at(vec,i) 
 }

 "[.Vector" <- function(vec, i, value)
 {
    vector_at(vec,i) = value #it's not working alone either, because R do not know about C++ references
 }

Unfortunately, R is detecting that it is an external pointer and forbid subsetting:

mv = vector_create(4)
mv[1]=5
mv[1]

Error in mv[1] = 5 : object of type 'externalptr' is not subsettable
Error in mv[1] : object of type 'externalptr' is not subsettable

After that I tried to make something like that:

"vector_at<-" <- function(vec, i, value) {
    print(vec)
    print(i)
    print(value)
    vector_set_at(vec,i,value)
    print(vec)
    print(i)
    print(value)
 }

What is interesting, in this function everything is working fine, but... after function ends and returning to main code, which called "vector_at<-"... vector changes to random number, like NULL or 5.

Do you have any ideas?

For now, one can use vector_set_at(vec,i,value) and vector_at(vec,i) for setting and getting item at index i.

from datastructures.

Try setting  the class attribute by callling the class() function

Marek Gagolewski, PhD

Sent from Type Mail

On Mar 20, 2015, 11:30, at 11:30, Maciej Bartoszuk [email protected] wrote:

Ok, I committed vector class in
1196208 .

Unfortunately, there are some issues in getting/setting one element,
like at() or operator[].

Firstly, I tried as you said

"[.Vector" <- function(vec, i)
{
   vector_at(vec,i) 
}

"[.Vector" <- function(vec, i, value)
{
vector_at(vec,i) = value #it's not working alone either, because R do
not know about C++ references
}

Unfortunately, R is detecting that it is an external pointer and forbid
subsetting:

mv = vector_create(4)
mv[1]=5
mv[1]

Error in mv[1] = 5 : object of type 'externalptr' is not subsettable
Error in mv[1] : object of type 'externalptr' is not subsettable

After that I tried to make something like that:

"vector_at<-" <- function(vec, i, value) {
   print(vec)
   print(i)
   print(value)
   vector_set_at(vec,i,value)
   print(vec)
   print(i)
   print(value)
}

What is interesting, in this function everything is working fine,
but... after function end and returning to main code, which called
"vector_at<-"... vector changes to random number, like NULL or 5.

Do you have any ideas?

For now, one can use vector_set_at(vec,i,value) and vector_at(vec,i)
for setting and getting item at index i.

---

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