matplotlib weirdness, it's not drawing my graph

Question

What happened is I followed this demo, I modified it to suit my needs had it working, changed it to use a function to draw two graphs but now it doesn't work at all using plt.show() or plt.savefig()

here's my code

import csv
import numpy as np

import matplotlib
matplotlib.use('Agg')

import matplotlib.pyplot as plt
import matplotlib.mlab as mlab

# I converted excel to a csv file
data = [x for x in csv.reader(open('ASS1_Q1.csv'))]

question1 = {}
question1['males'] = []
question1['females'] = []
for x in data:
    if x[0].lower() == "male":
        question1["males"].append(float(x[1]))
    elif x[0].lower() == "female":
        question1['females'].append(float(x[1]))
    else:
        print "Not a valid dataline", x

def plot_graph(data, filename):

    fig = plt.figure()
    ax = fig.add_subplot(111)

    n, bins, patches = ax.hist(np.array(data), bins=13, align='mid', facecolor='#888888')

    ax.set_xlabel('Speed in kph')
    ax.set_ylabel('Amount of Females')

    ax.set_xlim(min(data, max(data)))

    # plt.savefig(filename)
    plt.show()           

plot_graph(question1['males'], "ASS1Q1-males.eps")
#plot_graph(question1['females'], "ASSQ2-females.eps")
print summary(question1['males'])
print summary(question1['females'])

Can someone explain why this is happening? what am I doing wrong?

Answer 1

Try removing

import matplotlib
matplotlib.use('Agg')

The command

python -c 'import matplotlib; matplotlib.use("")'

will show you the valid string arguments that can be sent to matplotlib.use. On my machine, 'Agg' is listed as valid, though I get no output when this is set. If you are curious, you could just keep trying various options until you find one that works.

When you find the one that your prefer, you may also find it more convenient to set something like

backend      : GtkAgg

in your ~/.matplotlib/matplotlibrc instead of using matplotlib.use(...).