lstrend/lstrend

#!/usr/bin/python3

import argparse
import os
import time

factor = 0.99

def get_sizes(files):
    sizes = []
    for file in files:
        sizes.append(os.path.getsize(file))
    return sizes

def human_format(num):
    num = float('{:.3g}'.format(num))
    magnitude = 0
    while abs(num) >= 1024:
        magnitude += 1
        num /= 1024.0
    return '{}{}'.format('{:.3f}'.format(num).rstrip('0').rstrip('.'), ['', 'K', 'M', 'G', 'T', 'P'][magnitude])

def lstrend(files):
    avgrates = None
    sizes = None
    stamp = None
    while True:
        lastsizes = sizes
        laststamp = stamp
        sizes = get_sizes(files)
        stamp = time.monotonic()
        if lastsizes:
            diffs  = [s-lastsizes[c] for c,s in enumerate(sizes)]
            tdelta = stamp-laststamp
            rates  = [s/tdelta for s in diffs]
            if avgrates:
                avgrates = [avgrates[c]*factor+r*(1-factor) for c,r in enumerate(rates)]
            else:
                avgrates = rates
            print()
            for c,file in enumerate(files):
                print("{: <20} {: >10} {: >10}".format(file, human_format(avgrates[c]), human_format(sizes[c])))
        time.sleep(1)


def main():
    parser = argparse.ArgumentParser(description='Show trend in file size')
    parser.add_argument('files', nargs='+', help='files to list')

    args = parser.parse_args()

    lstrend(args.files)

if __name__ == "__main__":
    main()