One of the object oriented systems in the R language.
S3 is the main object oriented system in R.
Read more about it here
Base R uses S3.
The other two common object oriented systems are S4 and R5.
Questions tagged [r-s3]
149 questions
137
votes
6 answers
What does "S3 methods" mean in R?
Since I am fairly new to R, I do not know what the S3 methods and objects are. I found that there are S3 and S4 object systems, and some recommend to use S3 over S4 if possible (See Google's R Style Guide at…
jiggysoo
- 1,498
- 2
- 10
- 9
36
votes
1 answer
S3 method consistency warning when building R package with Roxygen
I have created a roxygen file for a function that uses S3 an class. I roxygenize and then build and check and get a warning:
* checking S3 generic/method consistency ... WARNING
common:
function(word.list, ...)
common.list:
function(word.list,…
Tyler Rinker
- 108,132
- 65
- 322
- 519
34
votes
1 answer
Safely creating S3 Generics in R
Henrik Bengtsson has provided the internet with a nice way of creating S3 generics in R without having to bother whether they were already created before... in 2002.
What his function setGenericsS3 does, is basically:
check whether the name is…
Joris Meys
- 106,551
- 31
- 221
- 263
19
votes
1 answer
Defining custom print methods for arrays and atomic vectors
I would like to define a different print method for arrays, but I’m afraid I’m not understanding something about S3 dispach. My custom print method is called if I call print(x) explicitly, but is not called if I just type x at the console. However,…
t-kalinowski
- 1,420
- 11
- 21
18
votes
1 answer
Proper way to implement S3 dispatch on R6 classes
I have an R6 class and I want to add an S3 method for it. The documentation I found mentioned briefly that in order to use S3 dispatch on R6 you must have class = TRUE, but I couldn't find an example of how it should be done.
I did see empirically…
DeanAttali
- 25,268
- 10
- 92
- 118
15
votes
1 answer
How to use S3 methods from another package which uses export rather than S3method in its namespace without using Depends or library()
I'm working on an R package at present and trying to follow the best practice guidelines provided by Hadley Wickham at http://r-pkgs.had.co.nz. As part of this, I'm aiming to have all of the package dependencies within the Imports section of the…
Nick Kennedy
- 12,510
- 2
- 30
- 52
13
votes
2 answers
Getting the object name for S3 print method failing
Define an object of S3 class "bar" and a print method:
foo=list(1)
class(foo) <- c("bar")
print.bar <- function(x,...){
cat("print.bar says this was ",deparse(substitute(x)),"\n")
}
Now print(foo) does this:
> print(foo)
print.bar says this was …
Spacedman
- 92,590
- 12
- 140
- 224
12
votes
1 answer
Extending dplyr and use of internal functions
I'm working on a fork of the RSQLServer package and am trying to implement joins. With the current version of the package, joins for any DBI-connected database are implemented using sql_join.DBIConnection. However, that implementation doesn't work…
Nick Kennedy
- 12,510
- 2
- 30
- 52
11
votes
1 answer
Defining a new class of functions in R
So I'm changing the class of some functions that I'm building in R in order to add a description attribute and because I want to use S3 generics to handle everything for me. Basically, I have a structure like
foo <- function(x) x + 1
addFunction <-…
AHP
- 147
- 8
10
votes
1 answer
How can I write a `%*%` method for a base matrix S3 subclass?
I'd like to write a %*% method for a base matrix subclass. My subclass is an S3 class and the documentation of help("%*%") says that %*% is a S4 generic and that S4 methods need to be written for a function of two arguments named x and y. I've…
Trevor
- 434
- 4
- 8
10
votes
1 answer
What are S1 and S2 classes?
In R there are S3, S4 and with R 2.12, reference classes (unofficially called S5 classes).
Is there such a thing as a S1 (or S2) class? If so, what are they? If not, why start with S3?
csgillespie
- 59,189
- 14
- 150
- 185
10
votes
1 answer
S3 method help (roxygen2)
I am trying to use a S3 method in a package and thought I understood how to set it up after asking a question here: S3 method consistency warning when building R package with Roxygen
But now I get results I don't expect. If I run the code below…
Tyler Rinker
- 108,132
- 65
- 322
- 519
10
votes
1 answer
override S3 methods in base R
I am attempting to over-ride the print.anova() function from the R stats package within a local package that I use when teaching. Basically, I want to remove the printing of the heading and add a "total" row without creating a new function (e.g.,…
D Ogle
- 407
- 2
- 13
9
votes
1 answer
Why doesn't class(data.frame(...)) show list inheritance?
It's often said that data.frame inherits from list, which makes sense given many common paradigms for accessing data.frame columns ($, sapply, etc.).
Yet "list" is not among the items returned in the class list of a data.frame object:
dat <-…
Ari B. Friedman
- 71,271
- 35
- 175
- 235
8
votes
2 answers
What's the preferred means for defining an S3 method in an R package without introducing a dependency?
I have an R package (not currently on CRAN) which defines a couple of S3 methods of generic functions from other packages (specifically knitr::knit_print and huxtable::as_huxtable). However, they're not a key part of my package, so I'd prefer not to…
Nick Kennedy
- 12,510
- 2
- 30
- 52