Standard deviation and standard error

t_test.py

#!/usr/bin/python3
# -*- coding: utf-8 -*-

# Copyright © 2016 Martin Ueding <mu@martin-ueding.de>

import argparse
import random
import time

import matplotlib.pyplot as pl
import numpy as np
import scipy.optimize as op


def get_measurement():
    new = random.gauss(0, 1)
    #new = random.triangular(0, 1, 0.7)
    return new


def main():
    options = _parse_args()

    measurements = []
    measurements.append(get_measurement())

    pl.ion()

    bins = 40

    while True:
        for i in range(20):
            measurements.append(get_measurement())

        pl.clf()
        pl.hist(measurements, color='0.8', bins=bins)

        count = len(measurements)

        mean = np.mean(measurements)
        std = np.std(measurements)
        err = std / np.sqrt(count)

        max_height = count / bins

        pl.plot([mean - err, mean + err], [max_height, max_height], color='red', marker='o')
        pl.plot([mean], [max_height], color='green', marker='o')
        max_height *= 0.9
        pl.plot([mean - std, mean + std], [max_height, max_height], color='green', marker='o')

        #time.sleep(0.5)
        pl.pause(0.1)


def _parse_args():
    '''
    Parses the command line arguments.

    :return: Namespace with arguments.
    :rtype: Namespace
    '''
    parser = argparse.ArgumentParser(description='')
    options = parser.parse_args()

    return options


if __name__ == '__main__':
    main()