Draw a graph using braille characters
Why zip?

You have:

dots  = [x for x, y in zip("7321", range(r1))]
dots += [x for x, y in zip("8654", range(r2))]


You're never using the second part of that zip. So you're basically making lists for the two ranges, making lists for the two zips, making lists for the outcomes of those things, all to drop most of the information.

You can simplify that to just:

dots = '7321'[:r1] + '8654'[:r2]


character name

Try to avoid building up strings with +=. Instead just use format:

character_name = "BRAILLE PATTERN DOTS-{}".format(join(sorted(dots)))