Playing around with an ascii histogram example

word_count_histogram.py

#!/usr/bin/env python
"""
Example wordcount and ascii histogram script

- Writes a data file in a temporary dir
- defines function to parse file into a word iterable
- Histogram class that does the word count and draws it as
  ascii strings with various sorting options

Example usage:

data_file = write_data_file()
histogram = Histogram()
histogram.populate(words(data_file))
print histogram.draw()

[    ] [    ] [====] [    ] [====] [    ] [    ] [====]
[    ] [    ] [====] [    ] [====] [    ] [    ] [====]
[    ] [    ] [====] [====] [====] [====] [====] [====]
[====] [====] [====] [====] [====] [====] [====] [====]
derp   wibble foo    baz    bork   womp   whizz  bar


"""
import os
import re
import string
import tempfile
import collections

PUNCTUATION = re.compile('[{}]'.format(re.escape(string.punctuation)))

DATA = \
"""
foo bar baz womp
whizz bar foo

womp. derp, bork!
bork bork bork!!
foo foo bar bar
baz whizz wibble

"""


def write_data_file():
    """
    create a tempfile containing the data fixture, return the
    filename

    """
    tempdir = tempfile.mkdtemp()
    datafile = os.path.join(tempdir, "data.txt")
    with open(datafile, 'w') as handle:
        handle.write(DATA)
    return datafile


def words(filename):
    """
    given a file containing whitespace/newline words,
    parse the file and clean up the words, then yield them on as
    an iterator
    """
    with open(filename, 'r') as handle:
        for line in handle:
            line = PUNCTUATION.sub('', line)
            linewords = (word.strip() for word in line.split() if word.strip())
            for word in linewords:
                yield word


class Column(list):
    """
    Column

    Helper class to contain column elements, plus some extra
    information to aid sorting
    """
    def __init__(self, *elements):
        super(Column, self).__init__(*elements)
        self.column_name = None
        self.value = 0


class Histogram(dict):
    """
    Histogram

    dictionary based helper object to populate and count words
    and draw an ascii histogram

    """
    def __init__(self):
        super(Histogram, self).__init__()
        self.height = None
        self.width = None
        self.column_width = None
        self.data_entry = None
        self.blank_entry = None
        self.columns = {}

    def populate(self, iterable):
        """
        populate

        Populate self by consuming the iterable provided,
        creating an entry for each word seem and keeping count of the
        columns and widths as they go by

        :param iterable: iterable word list generator

        """
        max_word_len = 0
        for word in iterable:
            self.setdefault(word, 0)
            self[word] += 1
            word_length = len(word)
            if word_length > max_word_len:
                max_word_len = word_length

        self.width = len(self)
        self.height = max(self.itervalues())
        self.column_width = max_word_len
        padding = self.column_width - 2
        self.data_entry = '[{}]'.format('='*padding)
        self.blank_entry = '[{}]'.format(' '*padding)
        self._build_columns()

    def _make_column(self, count, name):
        """
        build a column instance containing the appropriate filled
        and blank entries, set the name and value fields to aid
        sorting

        :param count: number of entries in the column
        :param name: name of the column

        :returns: Column instance

        """
        result = [name]
        result.extend(self.data_entry for i in range(count))
        result.extend(self.blank_entry for i in range(self.height-count))
        col = Column(result)
        col.value = count
        col.column_name = name
        return col

    def _build_columns(self):
        """
        build the internal column data structure so that we can consume
        it to draw the histogram
        """
        self.columns = {}
        for word, count in self.iteritems():
            column_name = word.ljust(self.column_width, ' ')
            column = self._make_column(count, column_name)
            self.columns[column_name] = column

    def _format(self, columns):
        """
        given an array of columns, draw the formatted histogram string

        :param columns: list of column instances

        """
        result = "\n"
        for i in range(1, self.height+2):
            result += ' '.join([col[-i] for col in columns if col])
            result += '\n'
        return result

    def draw(self):
        """
        draw - create an unsorted histogram string

        """
        values = self.columns.values()
        return self._format(values)

    def draw_sorted_size(self, descending=False):
        """
        draw sorted size

        create a histogram sorted by bin population, defaults to
        ascending order, this can be flipped using the descending=True flag

        """
        od = collections.OrderedDict(
            sorted(
                self.columns.iteritems(),
                key=lambda x: x[1].value,
                reverse=descending
            )
        )
        values = [od[k] for k in od]
        return self._format(values)

    def draw_sorted_title(self, descending=False):
        """
        draw sorted title - create a representation of the histogram
        sorted by title (alphabetically)

        """
        od = collections.OrderedDict(
            sorted(
                self.columns.iteritems(),
                key=lambda x: x[1].column_name,
                reverse=descending
            )
        )
        values = [od[k] for k in od]
        return self._format(values)


if __name__ == '__main__':
    #
    # main test program
    #
    # create test data file
    data_file = write_data_file()
    # create and populate the histogram instance
    histogram = Histogram()
    histogram.populate(words(data_file))

    # draw some histograms using various sorting approaches
    print histogram.draw()
    print histogram.draw_sorted_size()
    print histogram.draw_sorted_size(descending=True)
    print histogram.draw_sorted_title()
    print histogram.draw_sorted_title(descending=True)

    # clean up the data file
    os.remove(data_file)

Very nice. Don't forget some texts contain punctuation. Example: "The quick brown fox jumps over the lazy dog. The dog barks!"
"dog." and "dog" should both be treated as "dog"

@nottings update should take care of punctuation, non-ascii chars and unicode left as an exercise to the reader :)