cse30_variable_names_example.py

# probably about right
def variance(samples):
    mean = sum(samples) / len(samples)
    return sum((x - mean)**2 for x in samples) / len(samples)

# probably too short
def var(s):
    m = sum(s) / len(s)
    return sum((x - m)**2 for x in s) / len(s)

# probably too long
def compute_variance_of_samples(list_of_samples):
    mean_of_list_of_samples = sum(list_of_samples) / len(list_of_samples)
    return sum((x - mean_of_list_of_samples)**2 
               for x in list_of_samples) / len(list_of_samples)

# with nice documentation 
# Note: this function may be a bit too simple to include such verbose 
# documentation for, that said, it doesn't hurt 
def variance(samples):
    """Compute the (uncorrected) sample variance of `samples`.

    Args:
        samples (iterable): a 1-d iterable of values to compute the 
            variance of.

    Returns:
        The standard deviation.
    """
    mean = sum(samples) / len(samples)
    return sum((x - mean)**2 for x in samples) / len(samples)


if __name__ == '__main__':
    import numpy as np
    l = np.random.rand(100)
    print(l.var())
    print(variance(l))
    print(compute_variance_of_samples(l))
    print(var(l))
    print("Remember to check the undocumented version of `variance` too.")