Beginner Matplotlib, how to make random data for graph

Question

I'm playing around with matplotlib trying to learn its features but one problem I am struggling with is making it randomly produce data to test my graph. Can anyone tell me what I am doing incorrectly here?

import numpy as np

labels = numpy.random.random_integers(0, high=1, size=10000)
x = numpy.random.random_integers(1, high=10, size=10000)
y = numpy.random.random_integers(1, high=10, size=10000)

plt.ylabel("Y")
plt.xlabel("X")
plt.hist(x, label='1')
plt.hist(x[y==0], label='0')
plt.legend(loc='upper right')
plt.savefig('testRand.png')

Further to this, how can I distribute data within a range, for example if I want x to hold 10% 1's, 20% 2's, 70% 3's so this can be graphed and I can make my graphs look pretty/possibly hold meaningful distributions?

Thanks :)

I don't see anything "incorrect" with your code. Did you intend to use the labels sample for anything? Also, y==0 will be False everywhere because your lower limit for the y sample is 1. — askewchan
– askewchan, Commented Apr 4, 2014 at 2:46

askewchan · Accepted Answer · 2014-04-04 02:50:05Z

2

If you want to generate samples from meaningful distributions, many are supplied, for example:

x = np.random.exponential(2, 10000)

Many more are in scipy.stats:

from scipy import stats
stats.gausshyper.rvs(a, b, c, z, size=10000)

To do something custom like what you want you can either create your own distribution with scipy.stats.rv_continuous or rv_discrete, where you can define whatever pdf or pmf you wish.

Or, a simpler hack for your example might be:

np.random.choice([1, 2, 2, 3, 3, 3, 3, 3, 3, 3], size=10000)

1223333333

edited Apr 4, 2014 at 2:50

answered Apr 4, 2014 at 2:44

askewchan

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