helpers.py
a2aa8d535d7bmaster

helpers.py
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			# -- coding: utf-8 --
			"""some helper functions."""

			import numpy as np


			def load_data():
			"""load data."""
			data = np.loadtxt("dataEx3.csv", delimiter=",", skiprows=1, unpack=True)
			x = data[0]
			y = data[1]
			return x, y


			def load_data_from_ex02(sub_sample=True, add_outlier=False):
			"""Load data and convert it to the metric system."""
			path_dataset = "height_weight_genders.csv"
			data = np.genfromtxt(
			path_dataset, delimiter=",", skip_header=1, usecols=[1, 2])
			height = data[:, 0]
			weight = data[:, 1]
			gender = np.genfromtxt(
			path_dataset, delimiter=",", skip_header=1, usecols=[0],
			converters={0: lambda x: 0 if b"Male" in x else 1})
			# Convert to metric system
			height *= 0.025
			weight *= 0.454

			# sub-sample
			if sub_sample:
			height = height[::50]
			weight = weight[::50]

			if add_outlier:
			# outlier experiment
			height = np.concatenate([height, [1.1, 1.2]])
			weight = np.concatenate([weight, [51.5/0.454, 55.3/0.454]])

			return height, weight, gender


			def standardize(x):
			"""Standardize the original data set."""
			mean_x = np.mean(x)
			x = x - mean_x
			std_x = np.std(x)
			x = x / std_x
			return x, mean_x, std_x


			def build_model_data(height, weight):
			"""Form (y,tX) to get regression data in matrix form."""
			y = weight
			x = height
			num_samples = len(y)
			tx = np.c_[np.ones(num_samples), x]
			return y, tx