Plotting lots of histograms

histtest.py

import numpy as np
import pylab as plt
import string
import random

## Just generate some data
sets, items = 500, 200    # number of symbols, number of datapoints for each symbol
dataset = np.random.random((sets, items)) - 0.5
up = string.ascii_uppercase
n = len(up)
symbols = ["".join([up[(i/n) % n], up[i % n]]) for i in range(sets)]
###

for i in range(len(symbols)):
    plt.hist(dataset[i, :], 30, range=[-0.5, 0.5], label=symbols[i])

plt.show()