Letter parser for text files

parse.py

from string import ascii_lowercase
from collections import Counter
import matplotlib.pyplot as plt
import operator
import numpy as np
import glob

my_counter = Counter()

# for filename in glob.iglob(/home/max/*.txt):
for filename in glob.iglob(---PATH---):
    with open(filename) as f:
        my_counter+=Counter(letter for line in f
                      for letter in line.lower()
                      if letter in ascii_lowercase)

D=dict(my_counter)
D = sorted(D.items(), key=operator.itemgetter(1), reverse=True)
D.sort(key=lambda x: x[1], reverse=True)
people, score = zip(*D)
x_pos = np.arange(len(people))

slope, intercept = np.polyfit(x_pos, score, 1)
trendline = intercept + (slope * x_pos)

plt.plot(x_pos, trendline, color='red', linestyle='--')
plt.bar(x_pos, score,align='center')
plt.xticks(x_pos, people)
plt.ylabel('Time occured')
plt.xlabel('Letter')
plt.show()