Question

I am trying to make an iterative map and plot it. I am just starting to learn python.
Here is my code: I feel I am making an amature mistake in syntax, my code only gives my a straight line.

N = 10000
aa = linspace(2, 4, N)
xx = zeros(N)
for jj in range(N):a = aa[jj]
x0 = rand()
for ii in range(1, 100): x0 = a *x0 *(1 -x0)
xx[jj] = x0
plot(aa, xx, '.')

What am I doing wrong?
thanks.

Answer 1

With python the indenting is more important than in other languages.

Just by rearranging your code (and putting in namespaces and such, so it’s obvious where functions are coming from), i get this:

Here is the code:

import numpy
from matplotlib import pyplot
import random



N = 10000
aa = numpy.linspace(2, 4, N)
xx = numpy.zeros(N)
for jj in range(N):
    a = aa[jj]
    x0 = random.random()
    for ii in range(1, 100):
        xx[jj] = a *x0 *(1 -x0)

pyplot.plot(aa, xx, '.')
pyplot.show()