CoCalc -- relay

Think Stats by Allen B. Downey Think Stats is an introduction to Probability and Statistics for Python programmers.

This is the accompanying code for this book.

Website: http://greenteapress.com/wp/think-stats-2e/

Path: think-stats-code / relay_soln.py

Views: ⁷¹¹⁵
License: GPL3

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"""This file contains code used in "Think Stats",
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by Allen B. Downey, available from greenteapress.com
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Copyright 2014 Allen B. Downey
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License: GNU GPLv3 http://www.gnu.org/licenses/gpl.html
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"""
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import thinkstats2
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import thinkplot
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import relay
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def ObservedPmf(pmf, speed, label=None):
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    """Returns a new Pmf representing speeds observed at a given speed.
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    The chance of observing a runner is proportional to the difference
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    in speed.
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    Args:
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        pmf: distribution of actual speeds
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        speed: speed of the observing runner
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        label: string label for the new dist
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    Returns:
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        Pmf object
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    """
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    new = pmf.Copy(label=label)
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    for val in new.Values():
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        diff = abs(val - speed)
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        new.Mult(val, diff)
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    new.Normalize()
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    return new
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def main():
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    results = relay.ReadResults()
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    speeds = relay.GetSpeeds(results)
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    speeds = relay.BinData(speeds, 3, 12, 100)
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    # plot the distribution of actual speeds
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    pmf = thinkstats2.Pmf(speeds, 'actual speeds')
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    # plot the biased distribution seen by the observer
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    biased = ObservedPmf(pmf, 7.5, label='observed speeds')
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    thinkplot.Pmf(biased)
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    thinkplot.Save(root='observed_speeds',
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                   title='PMF of running speed',
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                   xlabel='speed (mph)',
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                   ylabel='PMF')
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    cdf = thinkstats2.Cdf(pmf)
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    cdf_biased = thinkstats2.Cdf(biased)
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    thinkplot.PrePlot(2)
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    thinkplot.Cdfs([cdf, cdf_biased])
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    thinkplot.Save(root='observed_speeds_cdf',
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                   title='CDF of running speed',
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                   xlabel='speed (mph)',
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                   ylabel='CDF')
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if __name__ == '__main__':
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    main()
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