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@kashif
kashif / cem.md
Last active September 18, 2024 21:33
Cross Entropy Method

Cross Entropy Method

How do we solve for the policy optimization problem which is to maximize the total reward given some parametrized policy?

Discounted future reward

To begin with, for an episode the total reward is the sum of all the rewards. If our environment is stochastic, we can never be sure if we will get the same rewards the next time we perform the same actions. Thus the more we go into the future the more the total future reward may diverge. So for that reason it is common to use the discounted future reward where the parameter discount is called the discount factor and is between 0 and 1.

A good strategy for an agent would be to always choose an action that maximizes the (discounted) future reward. In other words we want to maximize the expected reward per episode.

@karpathy
karpathy / pg-pong.py
Created May 30, 2016 22:50
Training a Neural Network ATARI Pong agent with Policy Gradients from raw pixels
""" Trains an agent with (stochastic) Policy Gradients on Pong. Uses OpenAI Gym. """
import numpy as np
import cPickle as pickle
import gym
# hyperparameters
H = 200 # number of hidden layer neurons
batch_size = 10 # every how many episodes to do a param update?
learning_rate = 1e-4
gamma = 0.99 # discount factor for reward
@ClintLiddick
ClintLiddick / rust-robotics-libraries.md
Last active July 26, 2024 13:41
Rust Libraries for Robotics

Motivation

tl;dr I want to use Rust to program robots. Help me find the best core libraries to build on.

Robotic systems require high performance and reliability, but also have enormous complexity in terms of algorithms employed, number of subsystems, embedded hardware control, and other metrics. Development is mostly split between C++ for performance and safety critical components, and MatLab or Python for quick research or task iteration.

@MatsuuraKentaro
MatsuuraKentaro / model.stan
Last active November 10, 2024 23:09
Tweedie distribution in Stan
data {
int N;
int M;
real<lower=0> Y[N];
}
parameters {
real<lower=0> mu;
real<lower=0> phi;
real<lower=1, upper=2> theta;
@jriguera
jriguera / email_notify.py
Last active August 7, 2025 20:15
Email from Python with Jinja2
#!/usr/bin/env python
# -*- coding: utf-8 -*-
# Python 3 and compatibility with Python 2
from __future__ import unicode_literals, print_function
import os
import sys
import re
import logging
@bishboria
bishboria / springer-free-maths-books.md
Last active September 25, 2025 06:28
Springer made a bunch of books available for free, these were the direct links
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@baraldilorenzo
baraldilorenzo / readme.md
Last active September 13, 2025 12:17
VGG-16 pre-trained model for Keras

##VGG16 model for Keras

This is the Keras model of the 16-layer network used by the VGG team in the ILSVRC-2014 competition.

It has been obtained by directly converting the Caffe model provived by the authors.

Details about the network architecture can be found in the following arXiv paper:

Very Deep Convolutional Networks for Large-Scale Image Recognition

K. Simonyan, A. Zisserman

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@chrisrzhou
chrisrzhou / git-advanced.md
Last active August 29, 2015 14:19
Git Resources

Git Advanced Resources

Interactive Rebase

  • Enter interactive rebase using git rebase -i
  • Some rebase options include:
    • squash: combine commits
    • edit: split commits (using git reset HEAD^)
    • reword: rename commit
    • pick: run commits in order