How to write generic function with two inputs?
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I am a newbee in programming, and I run into an issue with R about generic function: how to write it when there are multiple inputs?
For an easy example, for dataset and function
z <- c(2,3,4,5,8)
calc.simp <- function(a,x){a*x+8}
# Test the function:
calc.simp(x=z,a=3)
[1] 14 17 20 23 32
Now I change the class of z:
class(z) <- 'simp'
How should I write the generic function 'calc' as there are two inputs?
My attempts and errors are below:
calc <- function(x) UseMethod('calc',x)
calc(x=z)
Error in calc.simp(x = z) : argument "a" is missing, with no default
And
calc <- function(x,y) UseMethod('calc',x,y)
Error in UseMethod("calc", x, y) : unused argument (y)
My confusion might be a fundamental one as I am just a beginner. Please help! Thank you very much!
r generic-programming
asked Apr 3 at 19:36
Branda NewbeeBranda Newbee
585
add a comment |
I am a newbee in programming, and I run into an issue with R about generic function: how to write it when there are multiple inputs?
For an easy example, for dataset and function
z <- c(2,3,4,5,8)
calc.simp <- function(a,x){a*x+8}
# Test the function:
calc.simp(x=z,a=3)
[1] 14 17 20 23 32
Now I change the class of z:
class(z) <- 'simp'
How should I write the generic function 'calc' as there are two inputs?
My attempts and errors are below:
calc <- function(x) UseMethod('calc',x)
calc(x=z)
Error in calc.simp(x = z) : argument "a" is missing, with no default
And
calc <- function(x,y) UseMethod('calc',x,y)
Error in UseMethod("calc", x, y) : unused argument (y)
My confusion might be a fundamental one as I am just a beginner. Please help! Thank you very much!
r generic-programming
asked Apr 3 at 19:36
Branda NewbeeBranda Newbee
585
1
What do you expect to be returned fromcalc(x=z)? You aren't giving your function a value foraand your function depends on it. Also you can let your generic function know there may be other argumets withcalc <- function(x, ...) UseMethod('calc',x)
– MrFlick
Apr 3 at 19:45
What do you want your function to do? Your first function (calc.simp) still works even after changing the class of z.
– Luis
Apr 3 at 19:49
@MrFlick I simply want to test whether my generic function can work! It helps me understand the dispatch mechanism better. The 'function(x,...)' works perfectly for my question. Thank you so much! :)
– Branda Newbee
Apr 3 at 19:58
question is about dispatching? didn't see this keyword anywhere on this page, hence adding it here.
– chinsoon12
Apr 4 at 0:24
add a comment |
I am a newbee in programming, and I run into an issue with R about generic function: how to write it when there are multiple inputs?
For an easy example, for dataset and function
z <- c(2,3,4,5,8)
calc.simp <- function(a,x){a*x+8}
# Test the function:
calc.simp(x=z,a=3)
[1] 14 17 20 23 32
Now I change the class of z:
class(z) <- 'simp'
How should I write the generic function 'calc' as there are two inputs?
My attempts and errors are below:
calc <- function(x) UseMethod('calc',x)
calc(x=z)
Error in calc.simp(x = z) : argument "a" is missing, with no default
And
calc <- function(x,y) UseMethod('calc',x,y)
Error in UseMethod("calc", x, y) : unused argument (y)
My confusion might be a fundamental one as I am just a beginner. Please help! Thank you very much!
r generic-programming
asked Apr 3 at 19:36
Branda NewbeeBranda Newbee
585
I am a newbee in programming, and I run into an issue with R about generic function: how to write it when there are multiple inputs?
For an easy example, for dataset and function
z <- c(2,3,4,5,8)
calc.simp <- function(a,x){a*x+8}
# Test the function:
calc.simp(x=z,a=3)
[1] 14 17 20 23 32
Now I change the class of z:
class(z) <- 'simp'
How should I write the generic function 'calc' as there are two inputs?
My attempts and errors are below:
calc <- function(x) UseMethod('calc',x)
calc(x=z)
Error in calc.simp(x = z) : argument "a" is missing, with no default
And
calc <- function(x,y) UseMethod('calc',x,y)
Error in UseMethod("calc", x, y) : unused argument (y)
My confusion might be a fundamental one as I am just a beginner. Please help! Thank you very much!
r generic-programming
r generic-programming
asked Apr 3 at 19:36
Branda NewbeeBranda Newbee
585
asked Apr 3 at 19:36
Branda NewbeeBranda Newbee
585
asked Apr 3 at 19:36
Branda NewbeeBranda Newbee
585
asked Apr 3 at 19:36
Branda NewbeeBranda Newbee
585
asked Apr 3 at 19:36
Branda NewbeeBranda Newbee
585
585
1
What do you expect to be returned fromcalc(x=z)? You aren't giving your function a value foraand your function depends on it. Also you can let your generic function know there may be other argumets withcalc <- function(x, ...) UseMethod('calc',x)
– MrFlick
Apr 3 at 19:45
What do you want your function to do? Your first function (calc.simp) still works even after changing the class of z.
– Luis
Apr 3 at 19:49
@MrFlick I simply want to test whether my generic function can work! It helps me understand the dispatch mechanism better. The 'function(x,...)' works perfectly for my question. Thank you so much! :)
– Branda Newbee
Apr 3 at 19:58
question is about dispatching? didn't see this keyword anywhere on this page, hence adding it here.
– chinsoon12
Apr 4 at 0:24
add a comment |
1
What do you expect to be returned fromcalc(x=z)? You aren't giving your function a value foraand your function depends on it. Also you can let your generic function know there may be other argumets withcalc <- function(x, ...) UseMethod('calc',x)
– MrFlick
Apr 3 at 19:45
What do you want your function to do? Your first function (calc.simp) still works even after changing the class of z.
– Luis
Apr 3 at 19:49
@MrFlick I simply want to test whether my generic function can work! It helps me understand the dispatch mechanism better. The 'function(x,...)' works perfectly for my question. Thank you so much! :)
– Branda Newbee
Apr 3 at 19:58
question is about dispatching? didn't see this keyword anywhere on this page, hence adding it here.
– chinsoon12
Apr 4 at 0:24
1
1
What do you expect to be returned from
calc(x=z)? You aren't giving your function a value for a and your function depends on it. Also you can let your generic function know there may be other argumets with calc <- function(x, ...) UseMethod('calc',x)– MrFlick
Apr 3 at 19:45
What do you expect to be returned from
calc(x=z)? You aren't giving your function a value for a and your function depends on it. Also you can let your generic function know there may be other argumets with calc <- function(x, ...) UseMethod('calc',x)– MrFlick
Apr 3 at 19:45
What do you want your function to do? Your first function (calc.simp) still works even after changing the class of z.
– Luis
Apr 3 at 19:49
What do you want your function to do? Your first function (calc.simp) still works even after changing the class of z.
– Luis
Apr 3 at 19:49
@MrFlick I simply want to test whether my generic function can work! It helps me understand the dispatch mechanism better. The 'function(x,...)' works perfectly for my question. Thank you so much! :)
– Branda Newbee
Apr 3 at 19:58
@MrFlick I simply want to test whether my generic function can work! It helps me understand the dispatch mechanism better. The 'function(x,...)' works perfectly for my question. Thank you so much! :)
– Branda Newbee
Apr 3 at 19:58
question is about dispatching? didn't see this keyword anywhere on this page, hence adding it here.
– chinsoon12
Apr 4 at 0:24
question is about dispatching? didn't see this keyword anywhere on this page, hence adding it here.
– chinsoon12
Apr 4 at 0:24
add a comment |
1 Answer
1
active
oldest
votes
I'd suggest you model your generic function off of the template used by innumerable base R functions as, e.g., mean:
> mean
function (x, ...)
UseMethod("mean")
In your case, that would translate to the following generic which (if I understand your question correctly) works just fine:
calc <- function(x, ...) UseMethod('calc')
calc.simp <- function(a, x) {
x <- unclass(x)
a * x + 8
}
## Try it out
z <- c(2,3,4,5,8)
class(z) <- "simp"
calc.simp(x = z, 10)
## [1] 28 38 48 58 88
calc(x = z, 10)
## [1] 28 38 48 58 88
answered Apr 3 at 19:59
Josh O'BrienJosh O'Brien
130k18283391
add a comment |
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1 Answer
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active
oldest
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oldest
votes
I'd suggest you model your generic function off of the template used by innumerable base R functions as, e.g., mean:
> mean
function (x, ...)
UseMethod("mean")
In your case, that would translate to the following generic which (if I understand your question correctly) works just fine:
calc <- function(x, ...) UseMethod('calc')
calc.simp <- function(a, x) {
x <- unclass(x)
a * x + 8
}
## Try it out
z <- c(2,3,4,5,8)
class(z) <- "simp"
calc.simp(x = z, 10)
## [1] 28 38 48 58 88
calc(x = z, 10)
## [1] 28 38 48 58 88
answered Apr 3 at 19:59
Josh O'BrienJosh O'Brien
130k18283391
add a comment |
I'd suggest you model your generic function off of the template used by innumerable base R functions as, e.g., mean:
> mean
function (x, ...)
UseMethod("mean")
In your case, that would translate to the following generic which (if I understand your question correctly) works just fine:
calc <- function(x, ...) UseMethod('calc')
calc.simp <- function(a, x) {
x <- unclass(x)
a * x + 8
}
## Try it out
z <- c(2,3,4,5,8)
class(z) <- "simp"
calc.simp(x = z, 10)
## [1] 28 38 48 58 88
calc(x = z, 10)
## [1] 28 38 48 58 88
answered Apr 3 at 19:59
Josh O'BrienJosh O'Brien
130k18283391
add a comment |
I'd suggest you model your generic function off of the template used by innumerable base R functions as, e.g., mean:
> mean
function (x, ...)
UseMethod("mean")
In your case, that would translate to the following generic which (if I understand your question correctly) works just fine:
calc <- function(x, ...) UseMethod('calc')
calc.simp <- function(a, x) {
x <- unclass(x)
a * x + 8
}
## Try it out
z <- c(2,3,4,5,8)
class(z) <- "simp"
calc.simp(x = z, 10)
## [1] 28 38 48 58 88
calc(x = z, 10)
## [1] 28 38 48 58 88
answered Apr 3 at 19:59
Josh O'BrienJosh O'Brien
130k18283391
I'd suggest you model your generic function off of the template used by innumerable base R functions as, e.g., mean:
> mean
function (x, ...)
UseMethod("mean")
In your case, that would translate to the following generic which (if I understand your question correctly) works just fine:
calc <- function(x, ...) UseMethod('calc')
calc.simp <- function(a, x) {
x <- unclass(x)
a * x + 8
}
## Try it out
z <- c(2,3,4,5,8)
class(z) <- "simp"
calc.simp(x = z, 10)
## [1] 28 38 48 58 88
calc(x = z, 10)
## [1] 28 38 48 58 88
answered Apr 3 at 19:59
Josh O'BrienJosh O'Brien
130k18283391
edited Apr 3 at 20:04
answered Apr 3 at 19:59
Josh O'BrienJosh O'Brien
130k18283391
answered Apr 3 at 19:59
Josh O'BrienJosh O'Brien
130k18283391
answered Apr 3 at 19:59
Josh O'BrienJosh O'Brien
130k18283391
130k18283391
add a comment |
add a comment |
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What do you expect to be returned from
calc(x=z)? You aren't giving your function a value foraand your function depends on it. Also you can let your generic function know there may be other argumets withcalc <- function(x, ...) UseMethod('calc',x)– MrFlick
Apr 3 at 19:45
What do you want your function to do? Your first function (calc.simp) still works even after changing the class of z.
– Luis
Apr 3 at 19:49
@MrFlick I simply want to test whether my generic function can work! It helps me understand the dispatch mechanism better. The 'function(x,...)' works perfectly for my question. Thank you so much! :)
– Branda Newbee
Apr 3 at 19:58
question is about dispatching? didn't see this keyword anywhere on this page, hence adding it here.
– chinsoon12
Apr 4 at 0:24