问如何保存到img "dispersion_plot“NLTK？

EN

import nltk
from nltk import word_tokenize
import matplotlib.pyplot as plt

raw="This is the text where includes the word lawyers"

text1 = nltk.Text(word_tokenize(raw))

fig = plt.figure()
dplot = text1.dispersion_plot(["lawyers"])
# save the figure
fig.savefig('dispersion_plot.png')

import nltk
from nltk import word_tokenize
from matplotlib import pylab


def dispersion_plot(text, words, ignore_case=False, title="Lexical Dispersion Plot", filename='dispersion_plot.png'):
    text = list(text)
    words.reverse()

    if ignore_case:
        words_to_comp = list(map(str.lower, words))
        text_to_comp = list(map(str.lower, text))
    else:
        words_to_comp = words
        text_to_comp = text

    points = [
        (x, y)
        for x in range(len(text_to_comp))
        for y in range(len(words_to_comp))
        if text_to_comp[x] == words_to_comp[y]
    ]
    if points:
        x, y = list(zip(*points))
    else:
        x = y = ()
    pylab.plot(x, y, "b|", scalex=0.1)
    pylab.yticks(list(range(len(words))), words, color="b")
    pylab.ylim(-1, len(words))
    pylab.title(title)
    pylab.xlabel("Word Offset")
    # pylab.show()
    pylab.savefig(filename)


raw = "This is the text where includes the word lawyers"
text1 = nltk.Text(word_tokenize(raw))
dispersion_plot(text=text1, words=["lawyers"], filename='dispersion_plot.png')