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
6
votes
1 answer
Dispatch a custom method on S3*data.frame
I would like to define my own behavior (method) for the multiplication of a
data.frame with an object of a new S3 class. But I can't figure out how to get
methods dispatch to find my method. Is there a way?
First, I define S3 objects 'a' (oldClass…
pangia
- 1,164
- 10
- 11
6
votes
4 answers
Modify S3 object without returning it?
I'm new to object-oriented programming in R and struggle with how to properly write a function that modifies an object.
This example works:
store1 <- list(
apples=3,
pears=4,
fruits=7
)
class(store1) <- "fruitstore"
print.fruitstore <-…
Chris
- 2,256
- 1
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- 41
5
votes
1 answer
How can I define an S3 method for an unevaluated assignment expression?
tl;dr: R CMD check complains when I implement a generic for the S3 class <-, because it thinks that the function is a replacement function with incorrect arguments.
I need to define a set of S3 generics to walk an AST of unevaluated R…
Konrad Rudolph
- 530,221
- 131
- 937
- 1,214
5
votes
2 answers
Unexpected log2 error when defining S3 "Math" group generics for a new class
I am trying to use S3 "Math" group generics for a custom class. However I am getting a strange result: log() works while log2 and log10 produces errors. Below is a minimal example:
# simple class with just the new name
lameclass <- function(x) {
…
Karolis Koncevičius
- 9,417
- 9
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- 89
5
votes
1 answer
What are these square brackets for S3 classes?
I obtained this from an open source repo on git. This shows the writing of generic and methods for S3 classes. But I do not understand the notations or conventions that the functions are being assigned to. The following are my questions:
The use…
Justin Thong
- 321
- 3
- 12
5
votes
2 answers
checking S3 generic/method consistency ... WARNING
I have already read following two discussion:
Roxygen2 - how to properly document S3 methods
S3 method consistency warning when building R package with Roxygen
And following two…
David Lee
- 129
- 1
- 9
5
votes
2 answers
How do you extend rbind for a data.frame subclass?
My question is how do you extend rbind() to work with a data.frame subclass? I cannot seem to properly extend rbind() to work with even a very simple subclass. The following example demonstrates the issue:
Subclass and method definition:
new_df2 <-…
r_alanb
- 873
- 8
- 21
5
votes
2 answers
is.object and the S3 class system
Using the class function allows us to determine the class of an object:
> x = 5
> class(x)
[1] "numeric"
I also understand that we can use the is.object command to determine if an object has a class. However some object types are implicit, that…
csgillespie
- 59,189
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5
votes
2 answers
S3 operator overloading for multiple classes
I defined two classes that can successfully add two of their own objects or a number and one of their own objects.
a <- structure(list(val = 1), class = 'customClass1')
b <- structure(list(val = 1), class = 'customClass2')
`+.customClass1` <-…
takje
- 2,630
- 28
- 47
4
votes
1 answer
How to override default S3 function in R?
I want to override the default predict.lm function due to a bug:
library(datasets)
# Just a regular linear regression
fit <- lm(mpg~disp+hp+wt+drat, data=mtcars)
termplot(fit, terms=2, se=T)
Gives this error:
Error in predict.lm(model, type =…
Max Gordon
- 5,367
- 2
- 44
- 70
4
votes
2 answers
How do I conditionally provide S3 methods for S3 generics from another package?
I'm making a package for data manipulation that uses some other libraries under the hood. Let's say that my data always has a class "custom" and that I have a function custom_select() to select some columns.
I would like my package to have few…
bretauv
- 7,756
- 2
- 20
- 57
4
votes
1 answer
How to make a generic R function inherit the class of its input?
Let the following code:
x <- 1:5
class(x) <- "bar"
foo <- function(x) {
UseMethod("foo")
}
foo.bar <- function(x) {
y <- max(x)
return(y)
}
I would like the output of foo(x) to have the same class as x (i.e., "bar"). The obvious way…
Waldir Leoncio
- 10,853
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4
votes
2 answers
How to override the implementation of a non-generic function in R
In R, I have an S3 class that emulates a 1D vector, and so I want to implement custom versions of mean, sum, max, etc. Let's say it looks like this:
my_class = function(){
structure(list(), class='my_class')
}
All the above methods work fine, if…
Migwell
- 18,631
- 21
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4
votes
1 answer
How to adjust j in `[.data.table` without breaking data.table's custom evaluation?
I'm trying to extend data.table to speed up/standardize analyses of complex survey designs. To do so, I'm trying to add a light layer on top of [.data.table where I intercept the call in j and in a few circumstances replace the operation (e.g. the…
dothatrumba
- 67
- 6
4
votes
2 answers
Importing a package's S3 methods without importing its functions
I have the following dependency chain in a package I'm developing:
My package uses a class (trajectory) defined in package A (simmer).
It also uses an S3 method for that class (plot.trajectory), which is defined in package B (simmer.plot).
I can…
Accidental Statistician
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