wordcloud.py

# Author: Andreas Christian Mueller <t3kcit@gmail.com>
#
# (c) 2012
# Modified by: Paul Nechifor <paul@nechifor.net>
#
# License: MIT

import warnings
from random import Random
import os
import re
import sys
import numpy as np
from operator import itemgetter

from PIL import Image
from PIL import ImageDraw
from PIL import ImageFont

from .query_integral_image import query_integral_image

item1 = itemgetter(1)

FONT_PATH = os.environ.get("FONT_PATH", os.path.join(os.path.dirname(__file__),
                                                     "DroidSansMono.ttf"))
STOPWORDS = set([x.strip() for x in open(os.path.join(os.path.dirname(__file__),
                                                      'stopwords')).read().split('\n')])


class IntegralOccupancyMap(object):
    def __init__(self, height, width, mask):
        self.height = height
        self.width = width
        if mask is not None:
            # the order of the cumsum's is important for speed ?!
            self.integral = np.cumsum(np.cumsum(255 * mask, axis=1),
                                      axis=0).astype(np.uint32)
        else:
            self.integral = np.zeros((height, width), dtype=np.uint32)

    def sample_position(self, size_x, size_y, random_state):
        return query_integral_image(self.integral, size_x, size_y, random_state)

    def update(self, img_array, pos_x, pos_y):
        partial_integral = np.cumsum(np.cumsum(img_array[pos_x:, pos_y:], axis=1),
                                     axis=0)
        # paste recomputed part into old image
        # if x or y is zero it is a bit annoying
        if pos_x > 0:
            if pos_y > 0:
                partial_integral += (self.integral[pos_x - 1, pos_y:]
                                     - self.integral[pos_x - 1, pos_y - 1])
            else:
                partial_integral += self.integral[pos_x - 1, pos_y:]
        if pos_y > 0:
            partial_integral += self.integral[pos_x:, pos_y - 1][:, np.newaxis]

        self.integral[pos_x:, pos_y:] = partial_integral


def random_color_func(word=None, font_size=None, position=None,
                      orientation=None, font_path=None, random_state=None):
    """Random hue color generation.

    Default coloring method. This just picks a random hue with value 80% and
    lumination 50%.

    Parameters
    ----------
    word, font_size, position, orientation  : ignored.

    random_state : random.Random object or None, (default=None)
        If a random object is given, this is used for generating random numbers.

    """
    if random_state is None:
        random_state = Random()
    return "hsl(%d, 80%%, 50%%)" % random_state.randint(0, 255)


class WordCloud(object):
    """Word cloud object for generating and drawing.

    Parameters
    ----------
    font_path : string
        Font path to the font that will be used (OTF or TTF).
        Defaults to DroidSansMono path on a Linux machine. If you are on
        another OS or don't have this font, you need to adjust this path.

    width : int (default=400)
        Width of the canvas.

    height : int (default=200)
        Height of the canvas.

    ranks_only : boolean (default=False)
        Only use the rank of the words, not the actual counts.

    prefer_horizontal : float (default=0.90)
        The ratio of times to try horizontal fitting as opposed to vertical.

    mask : nd-array or None (default=None)
        If not None, gives a binary mask on where to draw words. If mask is not
        None, width and height will be ignored and the shape of mask will be
        used instead. All white (#FF or #FFFFFF) entries will be considerd
        "masked out" while other entries will be free to draw on. [This
        changed in the most recent version!]

    scale : float (default=1)
        Scaling between computation and drawing. For large word-cloud images,
        using scale instead of larger canvas size is significantly faster, but
        might lead to a coarser fit for the words.

    min_font_size : int (default=4)
        Smallest font size to use. Will stop when there is no more room in this
        size.

    font_step : int (default=1)
        Step size for the font. font_step > 1 might speed up computation but
        give a worse fit.

    max_words : number (default=200)
        The maximum number of words.

    stopwords : set of strings
        The words that will be eliminated.

    background_color : color value (default="black")
        Background color for the word cloud image.

    max_font_size : int or None (default=None)
        Maximum font size for the largest word. If None, height of the image is
        used.

    mode: string (default="RGB")
        Transparent background will be generated when mode is "RGBA" and
        background_color is None.

    Attributes
    ----------
    ``words_``: list of tuples (string, float)
        Word tokens with associated frequency.

    ``layout_`` : list of tuples (string, int, (int, int), int, color))
        Encodes the fitted word cloud. Encodes for each word the string, font
        size, position, orientation and color.

    Notes
    -----
    Larger canvases with make the code significantly slower. If you need a large
    word cloud, try a lower canvas size, and set the scale parameter.

    The algorithm might give more weight to the ranking of the words
    than their actual frequencies, depending on the ``max_font_size`` and the
    scaling heuristic.
    """

    def __init__(self, font_path=None, width=400, height=200, margin=2,
                 ranks_only=False, prefer_horizontal=0.9, mask=None, scale=1,
                 color_func=random_color_func, max_words=200, min_font_size=4,
                 stopwords=None, random_state=None, background_color='black',
                 max_font_size=None, font_step=1, mode="RGB"):
        if stopwords is None:
            stopwords = STOPWORDS
        if font_path is None:
            font_path = FONT_PATH
        self.font_path = font_path
        self.width = width
        self.height = height
        self.margin = margin
        self.ranks_only = ranks_only
        self.prefer_horizontal = prefer_horizontal
        self.mask = mask
        self.scale = scale
        self.color_func = color_func
        self.max_words = max_words
        self.stopwords = stopwords
        self.min_font_size = min_font_size
        self.font_step = font_step
        if isinstance(random_state, int):
            random_state = Random(random_state)
        self.random_state = random_state
        self.background_color = background_color
        if max_font_size is None:
            max_font_size = height
        self.max_font_size = max_font_size
        self.mode = mode

    def fit_words(self, frequencies):
        """Create a word_cloud from words and frequencies.

        Alias to generate_from_frequencies.

        Parameters
        ----------
        frequencies : array of tuples
            A tuple contains the word and its frequency.

        Returns
        -------
        self
        """
        return self.generate_from_frequencies(frequencies)

    def generate_from_frequencies(self, frequencies):
        """Create a word_cloud from words and frequencies.

        Parameters
        ----------
        frequencies : array of tuples
            A tuple contains the word and its frequency.

        Returns
        -------
        self

        """
        # make sure frequencies are sorted and normalized
        frequencies = sorted(frequencies, key=lambda x: x[1], reverse=True)
        frequencies = frequencies[:self.max_words]
        # largest entry will be 1
        max_frequency = float(np.max([freq for word, freq in frequencies]))

        for i, (word, freq) in enumerate(frequencies):
            frequencies[i] = word, freq / max_frequency

        self.words_ = frequencies

        if self.random_state is not None:
            random_state = self.random_state
        else:
            random_state = Random()

        if len(frequencies) <= 0:
            print("We need at least 1 word to plot a word cloud, got %d."
                  % len(frequencies))

        if self.mask is not None:
            mask = self.mask
            width = mask.shape[1]
            height = mask.shape[0]
            if mask.dtype.kind == 'f':
                warnings.warn("mask image should be unsigned byte between 0 and"
                              " 255. Got a float array")
            if mask.ndim == 2:
                boolean_mask = mask == 255
            elif mask.ndim == 3:
                # if all channels are white, mask out
                boolean_mask = np.all(mask[:, :, :3] == 255, axis=-1)
            else:
                raise ValueError("Got mask of invalid shape: %s" % str(mask.shape))
        else:
            boolean_mask = None
            height, width = self.height, self.width
        occupancy = IntegralOccupancyMap(height, width, boolean_mask)

        # create image
        img_grey = Image.new("L", (width, height))
        draw = ImageDraw.Draw(img_grey)
        img_array = np.asarray(img_grey)
        font_sizes, positions, orientations, colors = [], [], [], []

        font_size = self.max_font_size
        last_freq = 1.

        # start drawing grey image
        for word, freq in frequencies:
            # alternative way to set the font size
            if not self.ranks_only:
                font_size = freq / float(last_freq) * font_size
            while True:
                # try to find a position
                font = ImageFont.truetype(self.font_path, font_size)
                # transpose font optionally
                if random_state.random() < self.prefer_horizontal:
                    orientation = None
                else:
                    orientation = Image.ROTATE_90
                transposed_font = ImageFont.TransposedFont(font,
                                                           orientation=orientation)
                draw.setfont(transposed_font)
                # get size of resulting text
                box_size = draw.textsize(word)
                # find possible places using integral image:
                result = occupancy.sample_position(box_size[1] + self.margin,
                                                   box_size[0] + self.margin,
                                                   random_state)
                if result is not None or font_size == 0:
                    break
                # if we didn't find a place, make font smaller
                font_size -= self.font_step

            if font_size < self.min_font_size:
                # we were unable to draw any more
                break

            x, y = np.array(result) + self.margin // 2
            # actually draw the text
            draw.text((y, x), word, fill="white")
            positions.append((x, y))
            orientations.append(orientation)
            font_sizes.append(font_size)
            colors.append(self.color_func(word, font_size=font_size,
                                          position=(x, y),
                                          orientation=orientation,
                                          random_state=random_state,
                                          font_path=self.font_path))
            # recompute integral image
            if self.mask is None:
                img_array = np.asarray(img_grey)
            else:
                img_array = np.asarray(img_grey) + boolean_mask
            # recompute bottom right
            # the order of the cumsum's is important for speed ?!
            occupancy.update(img_array, x, y)
            last_freq = freq

        self.layout_ = list(zip(frequencies, font_sizes, positions, orientations, colors))
        return self

    def process_text(self, text):
        """Splits a long text into words, eliminates the stopwords.

        Parameters
        ----------
        text : string
            The text to be processed.

        Returns
        -------
        words : list of tuples (string, float)
            Word tokens with associated frequency.

        Notes
        -----
        There are better ways to do word tokenization, but I don't want to
        include all those things.
        """

        d = {}
        flags = (re.UNICODE if sys.version < '3' and type(text) is unicode
                 else 0)
        for word in re.findall(r"\w[\w']*", text, flags=flags):
            if word.isdigit():
                continue

            word_lower = word.lower()
            if word_lower in self.stopwords:
                continue

            # Look in lowercase dict.
            if word_lower in d:
                d2 = d[word_lower]
            else:
                d2 = {}
                d[word_lower] = d2

            # Look in any case dict.
            d2[word] = d2.get(word, 0) + 1

        d3 = {}
        for d2 in d.values():
            # Get the most popular case.
            first = max(d2.items(), key=item1)[0]
            d3[first] = sum(d2.values())

        # merge plurals into the singular count (simple cases only)
        for key in list(d3.keys()):
            if key.endswith('s'):
                key_singular = key[:-1]
                if key_singular in d3:
                    val_plural = d3[key]
                    val_singular = d3[key_singular]
                    d3[key_singular] = val_singular + val_plural
                    del d3[key]

        return d3.items()

    def generate_from_text(self, text):
        """Generate wordcloud from text.

        Calls process_text and generate_from_frequencies.

        Returns
        -------
        self
        """
        words = self.process_text(text)
        self.generate_from_frequencies(words)
        return self

    def generate(self, text):
        """Generate wordcloud from text.

        Alias to generate_from_text.

        Calls process_text and generate_from_frequencies.

        Returns
        -------
        self
        """
        return self.generate_from_text(text)

    def _check_generated(self):
        """Check if ``layout_`` was computed, otherwise raise error."""
        if not hasattr(self, "layout_"):
            raise ValueError("WordCloud has not been calculated, call generate first.")

    def to_image(self):
        self._check_generated()
        if self.mask is not None:
            width = self.mask.shape[1]
            height = self.mask.shape[0]
        else:
            height, width = self.height, self.width

        img = Image.new(self.mode, (width * self.scale, height * self.scale),
                        self.background_color)
        draw = ImageDraw.Draw(img)
        for (word, count), font_size, position, orientation, color in self.layout_:
            font = ImageFont.truetype(self.font_path, font_size * self.scale)
            transposed_font = ImageFont.TransposedFont(font,
                                                       orientation=orientation)
            draw.setfont(transposed_font)
            pos = (position[1] * self.scale, position[0] * self.scale)
            draw.text(pos, word, fill=color)
        return img

    def recolor(self, random_state=None, color_func=None):
        """Recolor existing layout.

        Applying a new coloring is much faster than generating the whole wordcloud.

        Parameters
        ----------
        random_state : RandomState, int, or None, default=None
            If not None, a fixed random state is used. If an int is given, this
            is used as seed for a random.Random state.

        color_func : function or None, default=None
            Function to generate new color from word count, font size, position
            and orientation.  If None, self.color_func is used.

        Returns
        -------
        self
        """
        if isinstance(random_state, int):
            random_state = Random(random_state)
        self._check_generated()

        if color_func is None:
            color_func = self.color_func
        self.layout_ = [(word_freq, font_size, position, orientation,
                         color_func(word=word_freq[0], font_size=font_size,
                                    position=position, orientation=orientation,
                                    random_state=random_state, font_path=self.font_path))
                        for word_freq, font_size, position, orientation, _ in self.layout_]
        return self

    def to_file(self, filename):
        """Export to image file.

        Parameters
        ----------
        filename : string
            Location to write to.

        Returns
        -------
        self
        """

        img = self.to_image()
        img.save(filename)
        return self

    def to_array(self):
        """Convert to numpy array.

        Returns
        -------
        image : nd-array size (width, height, 3)
            Word cloud image as numpy matrix.
        """
        return np.array(self.to_image())

    def __array__(self):
        """Convert to numpy array.

        Returns
        -------
        image : nd-array size (width, height, 3)
            Word cloud image as numpy matrix.
        """
        return self.to_array()

    def to_html(self):
        raise NotImplementedError("FIXME!!!")