DESCRIPTION

Students:  Please keep in mind the OMSI rules.  Save your files often,
make sure OMSI fills your entire screen at all times, etc.  Remember
that clicking CopyQtoA will copy the entire question box to the answer
box.

In questions involving code which will PARTIALLY be given to you in the
question specs, you may need add new lines.  There may not be
information given as to where the lines should be inserted.

MAKE SURE TO RUN THE CODE IN PROBLEMS THAT INVOLVING CODE!

QUESTION -ext .py -run 'python omsi_answer1.py'

The code below will descend through a directory tree, recording all the
file names, forming groups according to suffix.  It will return a Python
dictionary, with keys equal to the suffixes it found, and a count of the
number of files found for each suffix.  See the example.  Fill in the
blanks.

import os,sys

def getSuffix(s):
   tmp = s.split('.')
   if len(tmp) == 1: return None
   return tmp[-1]

def inspectFileNames(dct,dr,flst):

      suff = getSuffix(f)
      if suff == None: continue


def countLikeFiles():
   fileGrps =  {}
   os.path.walk('.',inspectFileNames,fileGrps)
   return fileGrps

# create test; make directory 'testcase', with files 'abc.x' and
# 'def.y', and a subdirectory 'a' with a file 'ghi.y'; in the end the
# function 'countLikeFiles()' will return a dictionary like
# {'y': 2, 'x': 1}

try: os.mkdir('testcase')
except: pass
os.chdir('testcase')
top = os.getcwd()
try:
   f = open('abc.x','w')
   f.close()
   f = open('def.y','w')
   f.close()
except: pass
try: os.mkdir('a')
except: pass
os.chdir('a')
try:
   f = open('ghi.y','w')
   f.close()
except: pass
os.chdir(top)

print countLikeFiles()

QUESTION -ext .py -run 'python omsi_answer2.py'

Here you will write a class 'mtrx', to store a matrix.  It will have
instance variables 'm', 'nr' and 'nc', which are the matrix, the number
of rows and the number of columns.  The variable 'm' will be
1-dimensional, i.e.  a list (not a list of lists), storing the matrix 
in row-major order.  There will be instance methods 'getElement' 
and 'putElement' to read/write from/to a specific element of the matrix, 
and 'mulvec' to multiply a specified vector by the matrix


class mtrx:


z = mtrx([1,2,3,8,9,10],3)
# storing the 3 x 2 matrix
#  1  2
#  3  8
#  9 10

print z.getElement(1,1)  # 8
z.putElement(1,0,12)
print z.m  # [1,2,12,8,9,10]
print z.getElement(1,0)  # 12
print z.mulvec([5,-2])  # [1,44,25]