Orbits/Code/NeuralNetworkSpecifications.py

import torch
from torch.autograd.functional import jacobian
import itertools
import math
import abc

    
class EstimandInterface():
    """
    This defines a clean interface for working with the estimand (i.e. thing we are trying to estimate).
    In general, we are trying to estimate the choice variables and the partial derivatives of the value functions.
    This 

    This class wraps output for the neural network (or other estimand), allowing me to 
        - easily substitute various types of launch functions by having a common interface
            - this eases testing
        - check dimensionality etc without dealing with randomness
            - again, easing testing
        - reason more cleanly about the component pieces
            - easing programming
        - provide a clean interface to find constellation level launch decisions etc.

    It takes inputs of two general categories:
        - the choice function results
        - the partial derivatives of the value function
    """
    def __init__(self, partials, choices, deorbits=None):
        self.partials = partials
        self.choices = choices
        
    @property
    def number_constellations(self):
        pass #fix this
        return self.choices.shape[-1]
    @property
    def number_states(self):
        pass #fix this
        return self.partials.shape[-1] #This depends on the debris trackers technically.

    def choice_single(self, constellation):
        #returns the launch decision for the constellation of interest
        
        filter_tensor = torch.zeros(self.number_constellations)
        filter_tensor[constellation] = 1.0
        
        return self.choices @ filter_tensor
    
    def choice_vector(self, constellation):
        #returns the launch decision for the constellation of interest as a vector
        
        filter_tensor = torch.zeros(self.number_constellations)
        filter_tensor[constellation] = 1.0
        
        return self.choices * filter_tensor
    
    def partial_vector(self, constellation):
        #returns the partials of the value function corresponding to the constellation of interest
        
        filter_tensor = torch.zeros(self.number_states)
        filter_tensor[constellation] = 1.0
        
        return self.partials @ filter_tensor
    
    def partial_matrix(self, constellation):
        #returns the partials of the value function corresponding to 
        #the constellation of interest as a matrix
        
        filter_tensor = torch.zeros(self.number_states)
        filter_tensor[constellation] = 1.0
        
        return self.partials * filter_tensor
    
    def __str__(self):
        #just a human readable descriptor
        return "Launch Decisions and Partial Derivativs of value function with\n\tlaunches\n\t\t {}\n\tPartials\n\t\t{}".format(self.choices,self.partials)


class ChoiceFunction(torch.nn.Module):
    """
    This is used to estimate the launch function
    """
    def __init__(self
                 ,batch_size
                 ,number_states
                 ,number_choices
                 ,number_constellations
                 ,layer_size=12
                ):
        super().__init__()
        
        #preprocess
        self.preprocess = torch.nn.Linear(in_features=number_states, out_features=layer_size)
        
        #upsample
        self.upsample = lambda x: torch.nn.Upsample(scale_factor=number_constellations)(x).view(batch_size
                                                                                            ,number_constellations
                                                                                            ,layer_size)
        
        self.relu = torch.nn.ReLU() #used for coersion to the state space we care about.
        
       
        #sequential steps
        self.sequential = torch.nn.Sequential(
            torch.nn.Linear(in_features=layer_size, out_features=layer_size)
            #who knows if a convolution might help here.
            ,torch.nn.Linear(in_features=layer_size, out_features=layer_size)
            ,torch.nn.Linear(in_features=layer_size, out_features=layer_size)
        )

        #reduce the feature axis to match expected results
        self.feature_reduction = torch.nn.Linear(in_features=layer_size, out_features=number_choices)

        
    def forward(self, input_values):
        
        intermediate_values = self.relu(input_values) #states should be positive anyway.
        
        intermediate_values = self.preprocess(intermediate_values)
        intermediate_values = self.upsample(intermediate_values)
        intermediate_values = self.sequential(intermediate_values)
        intermediate_values = self.feature_reduction(intermediate_values)
        
        intermediate_values = self.relu(intermediate_values) #launches are always positive, this may need removed for other types of choices.
        
        return intermediate_values

class PartialDerivativesOfValueEstimand(torch.nn.Module):
    """
    This is used to estimate the partial derivatives of the value functions
    """
    def __init__(self
                 ,batch_size
                 ,number_constellations
                 ,number_states
                 ,layer_size=12):
        super().__init__()
        self.batch_size = batch_size #used for upscaling
        self.number_constellations = number_constellations
        self.number_states = number_states
        self.layer_size = layer_size
        
        
        #preprocess (single linear layer in case there is anything that needs to happen to all states)
        self.preprocess = torch.nn.Sequential(
            torch.nn.ReLU() #cleanup as states must be positive
            ,torch.nn.Linear(in_features = self.number_states, out_features=self.number_states)
        )
        
        #upsample to get the basic dimensionality correct. From (batch,State) to (batch, constellation, state). Includes a reshape
        self.upsample = lambda x: torch.nn.Upsample(scale_factor=self.number_constellations)(x).view(self.batch_size
                                                                                            ,self.number_constellations
                                                                                            ,self.number_states)
        
        #sequential steps
        self.sequential = torch.nn.Sequential(
            torch.nn.Linear(in_features=number_states, out_features=layer_size)
            #who knows if a convolution or other layer type might help here.
            ,torch.nn.Linear(in_features=layer_size, out_features=layer_size)
            ,torch.nn.Linear(in_features=layer_size, out_features=layer_size)
        )

        #reduce the feature axis to match expected results
        self.feature_reduction = torch.nn.Linear(in_features=layer_size, out_features=number_states)
        
    def forward(self, states):
        #Note that the input values are just going to be the state variables
        #TODO:check that input values match the prepared dimension?
        
        #preprocess
        intermediate = self.preprocess(states)
        
        #upscale the input values
        intermediate = self.upsample(intermediate)
        
        #intermediate processing
        intermediate = self.sequential(intermediate)
        
        #reduce feature axis to match the expected number of partials
        intermediate = self.feature_reduction(intermediate)
        
        
        return intermediate
    

class EstimandNN(torch.nn.Module):
    """
    This neural network takes the current states as input values and returns both
    the partial derivatives of the value function and the launch function.
    """
    def __init__(self
                 ,batch_size
                 ,number_states
                 ,number_choices
                 ,number_constellations
                 ,layer_size=12
                ):
        super().__init__()
        

        self.partials_estimator = PartialDerivativesOfValueEstimand(batch_size, number_constellations, number_states, layer_size)
        self.launch_estimator = ChoiceFunction(batch_size, number_states, number_choices, number_constellations, layer_size)
        
    def forward(self, input_values):
        pass
        partials = self.partials_estimator(input_values)
        launch = self.launch_estimator(input_values)
        
        return EstimandInterface(partials,launch)