Assignment 5

Question

Recall the Python script for operating on sparse integer-valued 2D-matrices given in Assignment #4. We can define operations of single matrices that apply a particular function to each elemnt of that matrix, e.g., op1 * -1 (negation); similarly, we can define operations (besides addition and subtraction) on pairs of same-dimensioned matrices that apply a function to each pair of matched elements, e.g., (3 * op1) - op2. Each such operation can be specified by a symbol or string denoting that operation, an integer 1 or 2 indicating whether that operation is monadic or dyadic, and the Python expression associated with that operation (phrased in terms of op1 for monadic operations and op1 and op2 for dyadic operations). Given this, we can define a very simple scripting language consisting of the following statements:
• import file -- read in operation-specification file file.s2mop
• read file -- read in sparse 2D-matrix file from file file.s2m
• print file -- print sparse 2D-matrix file to the terminal
• write file -- write out sparse 2D-matrix file to file file.s2m
• res = mop op1 -- apply mondaic operator mop to sparse 2D-matrix op1 and store result in sparse 2D-matrix res.
• res = op1 dop op2 -- apply dyadic operator dop to sparse 2D-matrices op1 and op2 and store result in sparse 2D-matrix res.

Let such scripts be stored in files with a ".s2ms" extension.

Write and document a Python script s2m.py which takes as a command-line argument an s2m script and interprets the commands in this script. Where possible, define your own functions to simplify code structure; when you do, make sure these functions are documented with their own doc-strings and (where necessary) internal comments. Your script must work on s2m script file script1.s2ms, s2m operatio-specification file op1.s2mop, and s2m datafiles m1.s2m and m2.s2m to produce the output given in typescript-file s2m.script. You may assume that all given datafiles are formatted correctly and are readable.

Hints

You may find it useful to store matrices manipulated by the program as dictionaries nested inside a top-level dictionary. You may find it useful to store operation-specifications in a dictionary. You may find both lambda functions and the apply() function useful in dynamically interpreting operation-specifications.

Submission

Please hand in printed copies of all of your Python script files. You must also submit these files electronically using the submit-assignment command. At the top of each script, please include a triple-quoted docstring with your name and student number, the name of this course and the assignment number, and a brief description of your program; also include brief comments throughout your program describing various code-blocks. You do not have to develop your code on our CS departmental systems. However, as your code will be compiled and tested on our CS departmental systems (which use Python Version 2.4) as part of the assignment marking process, you should ensure that your code compiles and runs correctly on at least one of these systems.

Additional Notes:

• Feb 26, 6:00pm
  Assignment #5 posted.

Created: February 26, 2008
Last Modified: February 26, 2008