test7a.py

import numpy

test = False
file = 'data/task7test.txt' if test else 'data/task7.txt'

with open(file) as f:
    crabmarines = numpy.array([int(x) for x in next(f).split(',')])

bestPosition = 9999999999
for position in range(crabmarines.min(),crabmarines.max()+1):
    curPosition = numpy.absolute(numpy.subtract(position,crabmarines)).sum()
    if curPosition < bestPosition:
        bestPosition = curPosition
print(bestPosition)