Function capability for splot tool

[acampove]

Hi,

Thanks for your work writting the tool that calculates the sweights. However I think the user might not need the weights in an array but as a function. At the end the sWeights are just a 1D function of the mass. So what I think should happen is more like:

d_wgt = compute_sweights(model, data)

arr_wgt = d_wgt['nsig']

fun = Function(x=arr_mass, y=arr_wgt)
fun.save('swt_v1.json')

that way, if you need those weights you do:

fun = Function.load('swt_v1.json')
#For one mass value
wgt=fun(5202)
# or if you need the whole array
arr_wgt = fun([2464, 4564, 4945])

that way you would be able to keep around in disk many versions of the sweights (from different fitting models, for instance) and load them whenever you need them. I implemented a Function class in:

https://github.com/acampove/dmu/blob/main/src/dmu/stats/function.py
https://github.com/acampove/dmu/blob/main/tests/stats/test_function.py

feel free to pick up what you need from the code.