# Stock Market Prediction in Python Part 2

This post revisits the problem of predicting stock prices based on historical stock data using TensorFlow that was explored in a previous post. In the previous post, stock price was predicted solely based on the date. First, the date was converted to a numerical value in LibreOffice, then the resulting integer value was read into a matrix using numpy. As stated in the post, this method was not meant to be indicative of how actual stock prediction is done. This post aims to slightly improve upon the previous model and explore new features in tensorflow and Anaconda python. The corresponding source code is available here.

Note: See a later post Visualizing Neural Network Performance on High-Dimensional Data for code to help visualize neural network learning and performance.

# Multi-Layer Perceptrons and Back-Propagation; a Derivation and Implementation in Python

Artificial neural networks have regained popularity in machine learning circles with recent advances in deep learning. Deep learning techniques trace their origins back to the concept of back-propagation in multi-layer perceptron (MLP) networks, the topic of this post.

### Multi-Layer Perceptron Networks for Regression

A MLP network consists of layers of artificial neurons connected by weighted edges. Neurons are denoted $n_{ij}$ for the $j$-th neuron in the $i$-th layer of the MLP from left to right top to bottom. Inputs are fed into the leftmost layer and propagate through the network along weighted edges until reaching the final, or output, layer. An example of a MLP network can be seen below in Figure 1. Continue reading

# Eigenfaces versus Fisherfaces on the Faces94 Database with Scikit-Learn

In this post, two basic facial recognition techniques will be compared on the Faces94 database. Images from the Faces94 database are 180 by 200 pixels in resolution and were taken as the subjects were speaking to induce variations in the images. In order to train a classifier with the images, the raw pixel information is extracted, converted to grayscale, and flattened into vectors of dimension $180 \times 200 = 36000$. For this experiment, 12 subjects will be used from the database with 20 files will be used per subject. Each subject is confined to a unique directory that contains only 20 image files. Continue reading

# Wine Classification Using Linear Discriminant Analysis with Python and SciKit-Learn

In this post, a classifier is constructed which determines to which cultivar a specific wine sample belongs. Each sample consists a vector $\textbf{v}$ of 13 attributes of the wine, that is $\textbf{v} \in \mathbb{R}^{13}$. The attributes are as follows:

1. Alcohol
2. Malic acid
3. Ash
4. Alcalinity of ash
5. Magnesium
6. Total phenols
7. Flavanoids
8. Nonflavanoid phenols
9. Proanthocyanins
10. Color intensity
11. Hue
12. OD280/OD315 of diluted wines
13. Proline

Based on these attributes, the goal is to identify from which of three cultivars the data originated. The data set is available at the UCI Machine Learning Repository. Below are shown three sample rows from the data set. Continue reading

# Breast Cancer Malignancy Classification using PCA and Least Squares with Scikit-Learn

In this post, a linear regression classifier is constructed for the purpose of offering a medical diagnosis regarding breast cytology. The classifier receives a vector $\textbf{v} \in \mathbb{R}^9$ whose 9 components correspond to the following measurements:

1. Clump Thickness: 1 – 10
2. Uniformity of Cell Size: 1 – 10
3. Uniformity of Cell Shape: 1 – 10
4. Marginal Adhesion: 1 – 10
5. Single Epithelial Cell Size: 1 – 10
6. Bare Nuclei: 1 – 10
7. Bland Chromatin: 1 – 10
8. Normal Nucleoli: 1 – 10
9. Mitoses: 1 – 10

Given a vector of measurements, the classifier determines if the cells are benign or malignant. The data used in this post is courtesy of UCI’s machine learning repository and is available here. Continue reading