[Tutor] Retrieving numbers from a text

Rufino Beniga rbeniga04 at gmail.com
Wed Oct 24 00:45:17 CEST 2012

```*Problem*: Analyze a chaotic one-dimensional map: Write a program
OneDMapAnalyze.py that reads the data in OneDMap.txt. Calculate the mean
value of the iterates, printing the result to the terminal; again annotate
the output so that it is understandable. Determine the fraction of iterates
that have x > 0.5. Also, print out that result.

*The previous problem that I have already done:*
Iterate a chaotic one-dimensional map: Write a program OneDMapIterate.py that
iterates the function f(x) = 4.0 x ( 1 - x ). First, set the initial
condition x = 0.3. Then apply f(x) repeatedly to each new x. Iterate for
100 steps, printing on each line the iteration number and the successive x
values to file OneDMap.txt.

My program:

#Imports math functions
from math import *

#Initial condition for x
x = 0.3

#Opens onedmap.txt file and writes to it
file = open('onedmap.txt','w')

#Loop, replaces old x with new x i amount of times
for i in range(1,101):
x = 4.0*x*(1.0-x)

#Writes contents of loop to file
print >> file, 'Iterate number ', i, ': ', x

#Closes file
file.close()

My problem is, I don't know how to get ONLY the numbers from the
OneDMap.txt file. Also, assuming that I am able to do just that, how would
I get them into an array?

--
tell me i can't do it, then i'll prove you wrong!