sd() on greta_array does not return a greta_array

[hrlai]

Hi there, with the code below, applying sd() on a greta_array does not return the same class. Just wondering if it's intentional?

library(greta)
x <- normal(0, 1, dim = 10)
sd(x)   # class numeric
mean(x)  # class greta_array

I'm want to generate some calculated quantities by scaling using sd(x) so it'd be nice if it returns a greta_array. I could use var(x) or scale(x) (both return greta_array) but they are clunky in their own ways...

This was using greta_0.4.1.9000 on R version 4.1.3 (2022-03-10)

[njtierney]

Thanks for posting, @hrlai !

Confirming that I get the same result as you:

library(greta)
#> 
#> Attaching package: 'greta'
#> The following objects are masked from 'package:stats':
#> 
#>     binomial, cov2cor, poisson
#> The following objects are masked from 'package:base':
#> 
#>     %*%, apply, backsolve, beta, chol2inv, colMeans, colSums, diag,
#>     eigen, forwardsolve, gamma, identity, rowMeans, rowSums, sweep,
#>     tapply
greta_sitrep()
#> ℹ checking if python available
#> ✓ python (version 3.7) available
#> 
#> ℹ checking if TensorFlow available
#> ✓ TensorFlow (version 1.14.0) available
#> 
#> ℹ checking if TensorFlow Probability available
#> ✓ TensorFlow Probability (version 0.7.0) available
#> 
#> ℹ checking if greta conda environment available
#> ✓ greta conda environment available
#> 
#> ℹ Initialising python and checking dependencies, this may take a moment.
#> ✓ Initialising python and checking dependencies ... done!
#> 
#> ℹ greta is ready to use!
x <- normal(0, 1, dim = 10)
sd(x)
#> [1] NA
mean(x)
#> greta array (operation)
#> 
#>      [,1]
#> [1,]  ?
var(x)
#>      [,1]
#> [1,]   NA
scale(x)
#>       [,1]
#>  [1,]  ?  
#>  [2,]  ?  
#>  [3,]  ?  
#>  [4,]  ?  
#>  [5,]  ?  
#>  [6,]  ?  
#>  [7,]  ?  
#>  [8,]  ?  
#>  [9,]  ?  
#> [10,]  ?  
#> attr(,"scaled:center")
#> [1] NaN
#> attr(,"scaled:scale")
#> [1] 0

^{Created on 2022-03-18 by the reprex package (v2.0.1)}

Session info

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I think sd should be included, I'm not sure why it wasn't, I'll just need to check a few things first with Nick Golding, but I'll add this to the next milestone in the meantime.

Cheers!

Nick

[njtierney]

Intriguingly, there is no defined method for sd and var because sd and var are not generic methods in R

(learnt from: https://stackoverflow.com/questions/4728342/using-sd-as-a-generic-function-in-r)

I have started implementing this in #506