Numpy-powered CLI histogram

terminal_hist.py

import os
import numpy as np

term_rows, term_columns = map(int, os.popen('stty size', 'r').read().split())


def hist(xs, margin=10, width=term_columns):
    # I'm not sure why my font in iterm doesn't like \u2588, but it looks weird.
    #   It's too short and not the right width.
    chars = u' \u2581\u2582\u2583\u2584\u2585\u2586\u2587\u2589'
    width = term_columns - (2 * (margin + 1))
    # compute the histogram values as floats, which is easier, even though we renormalize anyway
    hist_values, bin_edges = np.histogram(xs, bins=width, density=True)
    # we want the highest hist_height to be 1.0
    hist_heights = hist_values / max(hist_values)
    # np.array(...).astype(int) will floor each value
    hist_chars = (hist_heights * (len(chars) - 1)).astype(int)
    cells = [chars[hist_char] for hist_char in hist_chars]

    # margin - size_of_integral_part - 1 (for +/- sign) - 1 (for decimal point) - 1 (because int floors, not ceils)
    float_fmt = lambda x: '%.*f' % (margin - int(np.log10(abs(x))) - 3, x)
    print '%*s[%s]%-*s' % (margin, float_fmt(bin_edges[0]), u''.join(cells), margin, float_fmt(bin_edges[-1]))

# example:
import scipy.stats
draws = scipy.stats.norm.rvs(size=1000, loc=240, scale=50)
hist(draws)

u'\u2588' looks out of whack in both Monaco and Droid Sans Mono, but it might be desirable in other terminals, so toying with the chars constant would be wise.

Example result:

$ py terminal.py
 86.746629[          ▁▁▂▂▁▃▃▃▂▄▅▅▅▅▉▅▇▆▄▅▇▄▃▅▃▃▂▂▁▂▁ ▁▁                      ]471.45819