def tweet_lengths(text):
    if len(text) < 100:
        return "short"
    elif 100 <= len(text) <= 135:
        return "medium"
    else:
        return "long"

tweets["tweet_length"] = tweets["text"].apply(tweet_lengths)

tl = {}
for candidate in ["clinton", "sanders", "trump"]:
    tl[candidate] = tweets["tweet_length"][tweets["candidate"] == candidate].value_counts()

fig, ax = plt.subplots()
width = .5
x = np.array(range(0, 6, 2))
ax.bar(x, tl["clinton"], width, color='g')
ax.bar(x + width, tl["sanders"], width, color='b')
ax.bar(x + (width * 2), tl["trump"], width, color='r')

ax.set_ylabel('# of tweets')
ax.set_title('Number of Tweets per candidate by length')
ax.set_xticks(x + (width * 1.5))
ax.set_xticklabels(('long', 'medium', 'short'))
ax.set_xlabel('Tweet length')
plt.show()