This returns the files in the current directory that are statistical outliers in terms of file size

outlier.py

#!/usr/bin/env python3
""" 
@atucom
This returns the files in the target directory that are
 statistical outliers in terms of file size
This is useful in the quest for finding target data.
"""
from __future__ import division
import argparse
import sys

try:
    import os
    import numpy
except ImportError as e:
    print(e)
    quit(1)

# Median absolute deviation
# stole the complicated stuff from stackoverflow, thanks!
def mad(data, axis=None):
    return numpy.mean(numpy.abs(data - numpy.mean(data, axis)), axis)

def _mad(x):
    return numpy.abs(x - numpy.median(x)) / mad(x)

def getFiles(directory):
    # Gets files for the target directory
    try:
        filenames = os.listdir(path = directory)
    except FileNotFoundError:
        print("Directory not found, try again")
        exit(1)
    files = {}
    for filename in filenames:
        files[filename] = os.stat(directory + '/' + filename).st_size
    return files

def outlierFileNames(files):
    # You have to calculate the mad first, so grab all the values and get the standard deviation back as "a"
    filesizes = [size for filename, size in files.items()]
    madDeviations = _mad(filesizes)
    threshold = 1.4826 # I _think_ this is right, someone please correct me if i'm not
    # move around by index, if the position of mad is greater than w/e thrshold, then return that item back to us:
    for index in range(len(madDeviations)):
        if madDeviations[index] > threshold:
            print(list(files.items())[index][0])
def main():
    """Main Execution"""
    parser = argparse.ArgumentParser(
        description='Returns files with outlier filesizes',
        epilog="Example: \n\t %s <dir to scan>"%sys.argv[0])

    parser.add_argument(
        '-d','--dir',
        metavar='Directory',
        dest='dir',
        help='Directory to scan'
        )

    args = parser.parse_args()
    if args.dir:
        files = getFiles(args.dir)
        outlierFileNames(files)
    else:
        files = getFiles('.')
        outlierFileNames(files)

if __name__ == '__main__':
    sys.exit(main())