Events spread over a number of units

Exceptions example from a Well House Consultants training course
More on Exceptions [link]

This example is described in the following article(s):
• How many times ... has this loco headed west through Tenby? - Python exceptions - [link]

This example references the following resources:
http://www.railpro.co.uk/magazine/?idArticles=393

Source code: dbnover Module: Y109

import random

# Events spread over a number of units

""" If a train pulled by an HST power car has visited Pembroke Dock on
average 12 times a year, how many times has each of the 117 power cars
that form part of the Great Western fleet been at the buffers there?"""

# Distribute 360 events over 117 units

# http://www.railpro.co.uk/magazine/?idArticles=393
# Say 12 per annum over 30 years

nunits = 117
nevents = 12 * 30

# It's random. Use start of Monte Carlo method - run 32 simulations

for k in range(32):

        # distribute the events between the units

        units = [0] * nunits
        for event in range(nevents):
                which = random.randint(1,nunits)
                units[which-1] += 1

        # count up the number of events that have happened to each unit

        counter = []
        for eventcount in units:
           while True:
                try:
                        counter[eventcount] += 1
                        break
                except:
                        counter += [0]

        print counter

""" Results:

wizard:nov12 graham$ python dbnover
[6, 17, 22, 30, 18, 13, 6, 4, 1]
[7, 14, 27, 27, 20, 9, 6, 6, 1]
[6, 19, 26, 20, 17, 20, 5, 3, 0, 0, 1]
[5, 18, 23, 30, 20, 7, 10, 3, 0, 0, 1]
[5, 17, 29, 21, 18, 18, 4, 4, 1]
[5, 16, 24, 34, 18, 7, 8, 2, 2, 1]
[10, 17, 17, 28, 19, 12, 9, 5]
[5, 17, 27, 22, 19, 17, 8, 2]
[8, 18, 27, 22, 16, 11, 9, 4, 0, 1, 0, 0, 1]
[7, 15, 22, 27, 22, 14, 8, 2]
[5, 13, 28, 32, 16, 12, 8, 2, 0, 1]
[6, 25, 22, 19, 20, 13, 2, 6, 2, 1, 1]
[6, 13, 27, 31, 19, 8, 8, 4, 1]
[6, 17, 24, 28, 18, 11, 8, 4, 1]
[3, 16, 30, 27, 19, 11, 6, 4, 1]
[5, 15, 25, 33, 16, 14, 6, 0, 1, 2]
[8, 20, 17, 28, 21, 10, 6, 4, 3]
[10, 17, 22, 23, 17, 15, 8, 2, 2, 1]
[5, 19, 26, 27, 20, 7, 3, 7, 2, 0, 1]
[5, 18, 25, 23, 25, 12, 3, 4, 1, 1]
[7, 17, 21, 30, 16, 15, 6, 4, 1]
[8, 17, 19, 27, 19, 15, 11, 1]
[8, 11, 27, 25, 27, 10, 5, 1, 2, 1]
[7, 15, 21, 30, 20, 14, 8, 1, 1]
[10, 12, 29, 24, 16, 14, 6, 3, 0, 3]
[8, 13, 30, 19, 24, 14, 3, 3, 2, 1]
[3, 21, 20, 29, 19, 16, 7, 2]
[8, 17, 26, 23, 19, 9, 7, 5, 3]
[4, 16, 26, 31, 19, 10, 4, 7]
[4, 19, 28, 23, 18, 16, 2, 5, 1, 1]
[2, 18, 26, 28, 22, 12, 7, 1, 0, 1]
[6, 19, 25, 21, 19, 15, 8, 3, 1]
wizard:nov12 graham$

"""

Learn about this subject

This module and example are covered on the following public courses:
* Learning to program in Python
* Python Programming
* Intermediate Python
Also available on on site courses for larger groups

Books covering this topic

Yes. We have over 700 books in our library. Books covering Python are listed here and when you've selected a relevant book we'll link you on to Amazon to order.

Other Examples

This example comes from our "Exceptions" training module. You'll find a description of the topic and some other closely related examples on the "Exceptions" module index page.

Full description of the source code

You can learn more about this example on the training courses listed on this page, on which you'll be given a full set of training notes.

Many other training modules are available for download (for limited use) from our download centre under an Open Training Notes License.

Other resources

• Our Solutions centre provides a number of longer technical articles.
• Our Opentalk forum archive provides a question and answer centre.
• The Horse's mouth provides a daily tip or thought.
• Further resources are available via the resources centre.
• All of these resources can be searched through through our search engine
• And there's a global index here.

Web site author

This web site is written and maintained by Well House Consultants.

Purpose of this website

This is a sample program, class demonstration or answer from a training course. It's main purpose is to provide an after-course service to customers who have attended our public private or on site courses, but the examples are made generally available under conditions described below.

Conditions of use

Past attendees on our training courses are welcome to use individual examples in the course of their programming, but must check the examples they use to ensure that they are suitable for their job. Remember that some of our examples show you how not to do things - check in your notes. Well House Consultants take no responsibility for the suitability of these example programs to customer's needs.

This program is copyright Well House Consultants Ltd. You are forbidden from using it for running your own training courses without our prior written permission. See our page on courseware provision for more details.

Any of our images within this code may NOT be reused on a public URL without our prior permission. For Bona Fide personal use, we will often grant you permission provided that you provide a link back. Commercial use on a website will incur a license fee for each image used - details on request.