hists.py

"""
Input is one number per line

Output is json of the form:
[
    {
        'bin' : bin1,
        'value' : value1
    },
    {
        'bin' : bin2,
        'value' : value2
    },
]

Set UPDATE_EVERY to whatever you want. set it to 10 and you'll get a 
new histogram output every 10th input

Invocation:
cat numbers.txt | python -u hists.py
"""

import sys, numpy

UPDATE_EVERY = 5

arr = numpy.array([])
counter = 0

for line in sys.stdin:
    counter += 1
    arr = numpy.append(arr, float(line.strip()))
    if counter % UPDATE_EVERY == 0:
        h = numpy.histogram(arr)
        output = []
        for count, bin in zip(h[0], h[1]):
            output.append({'bin':bin, 'count':count})
        print output