COMP9044 Week 07 Laboratory Exercises Solution

Before the lab you should re-read the relevant lecture slides and their accompanying examples.


Set up for the lab by creating a new directory called lab07 and changing to this directory.
$ mkdir lab07
$ cd lab07
There are some provided files for this lab which you can fetch with this command:
$ 2041 fetch lab07
If you're not working at CSE, you can download the provided files as a zip file or a tar file.


A citizen science project monitoring whale populations has files of containing large numbers of whale observations. Each line in these files contains:
$ head whales0.txt
18/01/18 9 Pygmy right whale
01/09/17 21 Southern right whale
16/02/18 4 Striped dolphin
02/07/17 4 Common dolphin
19/02/18 4 Blue whale
21/02/18 38 Dwarf sperm whale
14/06/17 29 Southern right whale
20/06/17 3 Spinner dolphin
22/07/17 34 Indo-Pacific humpbacked dolphin
20/03/18 7 Long-finned pilot whale
Write a Python program orca.py which prints a count of the number of observations of Orcas in the files.
Your program should take 1 or more filenames as command line arguments.
$ ./orca.py whales0.txt
1245 Orcas reported
$ ./orca.py whales0.txt whales1.txt whales2.txt
3150 Orcas reported
Note: each line records one pod of whales
Your program should print the number of individual Orca observed - it needs to sum each pod of Orcas.

When you think your program is working, you can use autotest to run some simple automated tests:
$ 2041 autotest orca
When you are finished working on this exercise, you must submit your work by running give :
$ give cs2041 lab07_orca orca.py


Write a Python program whale_summary.py which take one or more files on the command line.
whale_summary.py should print for, every whale species in the file, how many pods were seen and how many total whales were seen of that species.
Whale species should be listed in alphabetic order.
All whale names should be converted to lower case.
All whale names should be converted to singular form - assume this can be done safely by deleting a trailing 's' if it is present.
$ ./whale_summary.py whales0.txt
blue whale observations: 51 pods, 1171 individuals bryde's whale observations: 47 pods, 1023 individuals
coastal bottlenose dolphin observations: 53 pods, 1169 individuals common dolphin observations: 62 pods, 1232 individuals dwarf minke whale observations: 49 pods, 1080 individuals dwarf sperm whale observations: 58 pods, 1272 individuals fin whale observations: 65 pods, 1251 individuals humpback whale observations: 55 pods, 1071 individuals
indo-pacific humpbacked dolphin observations: 43 pods, 897 individuals long-finned pilot whale observations: 50 pods, 996 individuals orca observations: 53 pods, 1245 individuals
pygmy right whale observations: 59 pods, 1260 individuals pygmy sperm whale observations: 57 pods, 1346 individuals sei whale observations: 55 pods, 929 individuals short-finned pilot whale observations: 68 pods, 1344 individuals southern right whale observations: 55 pods, 1252 individuals spinner dolphin observations: 52 pods, 1118 individuals striped dolphin observations: 68 pods, 1337 individuals
$ ./whale_summary.py messy_whales0.txt blue whale observations: 2 pods, 27 individuals dwarf minke whale observations: 6 pods, 132 individuals orca observations: 2 pods, 48 individuals

When you think your program is working, you can use autotest to run some simple automated tests:
$ 2041 autotest whale_summary
When you are finished working on this exercise, you must submit your work by running give :
$ give cs2041 lab07_whale_summary whale_summary.py


Write a Python program summing_numbers.py which given a file as a command line argument, prints the sum of all the numbers in the file.
A number for the purposes of this exercise is any sequence of consecutive digits.
Note only the digits 0-9 are considered parts of numbers. The characters '.' and '-' are not considered part of numbers.
For example, the string the "It was -42.5C outside" should be treated as containing the numbers 42 and 5.
$ ./summing_numbers.py A-Tale-of-Two-Cities.txt
7104
$ ./summing_numbers.py Pride-and-Prejudice.txt 46520

When you think your program is working, you can use autotest to run some simple automated tests:
$ 2041 autotest summing_numbers
When you are finished working on this exercise, you must submit your work by running give :
$ give cs2041 lab07_summing_numbers summing_numbers.py


Write a Python program python_print.py which is given a single argument. It should output a Python program which when run, prints this string. For example:
$ ./python_print.py "hello world, how are you?" | python3 hello world, how are you?
$ ./python_print.py "I'm So Meta, Even This Acronym" > new_program.py
$ chmod +x new_program.py
$ ./new_program.py
I'm So Meta, Even This Acronym


When you think your program is working, you can use autotest to run some simple automated tests:
$ 2041 autotest python_print
When you are finished working on this exercise, you must submit your work by running give :
$ give cs2041 lab07_python_print python_print.py


Write a Python program python_print_n.py which is given a two arguments, an integer n and a string.
If n is 1 it should output a Python program which prints the string.
If n is 2 it should output a Python program which prints a Python program which prints the string.
If n is 3 it should output a Python program which prints a Python program which prints a Python program which prints the string.
And so on for any value of n.
$ ./python_print_n.py 1 "hello world, how are you?" | python3 hello world, how are you?
$ ./python_print_n.py 2 "hello world, how are you?" | python3 | python3 hello world, how are you?
$ ./python_print_n.py 3 "hello world, how are you?" | python3 | python3 | python3 hello world, how are you?
$ ./python_print_n.py 10 "Now that's a lot of python" | python3 | python3 | python3 | python3 | python3 | python3 | python3 | python3 | python3 | python3
Now that's a lot of python

When you think your program is working, you can use autotest to run some simple automated tests:
$ 2041 autotest python_print_n
When you are finished working on this exercise, you must submit your work by running give :
$ give cs2041 lab07_python_print_n python_print_n.py


Write a Python program python_print_inf.py which prints it's own soruce code.
The program can not use the open function.
The program can not use the inspect module.
$ ./python_print_inf.py > new_program.py
$ diff -s python_print_inf.py new_program.py
Files python_print_inf.py and new_program.py are identical
$ chmod +x new_program.py
$ ./new_program.py > second_order_program.py
$ diff -s python_print_inf.py second_order_program.py
Files python_print_inf.py and second_order_program.py are identical
$ ./python_print_inf.py | python3 | python3 | python3 | python3 | python3 > nth_program.py
$ diff -s python_print_inf.py nth_program.py
Files python_print_inf.py and nth_program.py are identical

When you think your program is working, you can use autotest to run some simple automated tests:
$ 2041 autotest python_print_inf
When you are finished working on this exercise, you must submit your work by running give :
$ give cs2041 lab07_python_print_inf python_print_inf.py


When you are finished each exercises make sure you submit your work by running give .
You can run give multiple times. Only your last submission will be marked.
Don't submit any exercises you haven't attempted.
You check the files you have submitted here.
After automarking is run by the lecturer you can view your results here. The resulting mark will also be available via give's web interface.
Lab Marks
When all components of a lab are automarked you should be able to view the the marks via give's web interface or by running this command on a CSE machine:
$ 2041 classrun -sturec

For all enquiries, please email the class account at cs2041@cse.unsw.edu.au
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