Programmers must learn how to use frameworks.

In this course, you are learning about the Textbook Collections Framework.

You will not have the luxery to change the framework in any way.

You must learn to do what you need to do with what is provided.

Sometimes, this takes ingenuity and trial and error.

Make sure you use the provided input.txt starter file to test your code.

It must be located in the same folder as your Python file.

Compare your results carefully to the "Programming Activity 5 - Expected Output" document.

You have 5 parts to complete.

Each part requires writing the code for the body of a function.

Do not add, change, or delete any code outside of these function bodies.

Each function already has all the parameters you might need.

Make use of these parameters as needed within the function body.

You do not need to use the parameter "words" in your code.

As described in the function comments, "words" is a list of words.

Its words contain only lowercase letters and there is no punctuation.

An iterator for this list, "wordsIter", is also passed to the functions.

"wordsIter" would not make sense without describing what it iterates.

Your code can make use of "wordsIter" to access the words list.

However, you could access "words" directly in a "for" loop, if you want.

Part 1

------

Call first() to prime the list iterator.

Use a while loop with a hasNext() condition to traverse the words list.

In the while block:

Use next() to get the next word.

Use "word" as the name of the variable to store this word.

Determine if this word is in the removals list.

To do this, use:

if (word in removals):

If the word is in the removals list:

Call remove() on the list iterator to remove it from the words list.

Part 2

------

Introduce a variable called previousWord and initialize it to an empty string.

Call first() to prime the list iterator.

Use a while loop with a hasNext() condition to traverse the words list.

In the while block:

Use next() to get the next word.

If the word is equal to "first" or word is equal to "last", then

update the value of previousWord to be the current word and

use continue to keep looping.

If the word is equal to the previous word, call remove() on the list iterator.

Update the value of previousWord to be the current word.

Part 3

------

This is similar to part 1.

Instead of the removals list, use the misspellings list.

Instead of using remove():

Call insert() on the list iterator to insert the flag text.

Then call next() on the list iterator to move past the flag.

Part 4

------

The strategy here is to iterate through the list to:

Count the number of "first" words.

Remove each of the "first" words as they are encountered.

Then use the count to control another loop to:

Insert new "first" words at the beginning of the list.

For each one:

Call first() to prime the list iterator.

If there is a next word, call next() to establish the insertion point.

Call insert() to insert a "first" word.

Since part 4 is one of the more difficult parts,

here is its solution as a free gift:

# Part 4:

# Move all occurrences of "first" to the front of the words list.

# Input:

# words - an ArrayList of words, no uppercase, no punctuation

# wordsIter - a list iterator for the words list

def moveFirstLit(words, wordsIter):

countFirst = 0

wordsIter.first()

while (wordsIter.hasNext()):

word = wordsIter.next()

if (word == FIRST):

wordsIter.remove()

countFirst += 1

for count in range(countFirst):

wordsIter.first()

if (wordsIter.hasNext()):

wordsIter.next()

wordsIter.insert(FIRST)

Make sure you study this code line by line.

Make sure you understand everything about how it works.

The FIRST constant (a convenience variable), is setup near the top of the starter code.

Part 5

------

The strategy here is to iterate through the list to:

Count the number of "last" words.

Remove each of the "last" words as they are encountered.

Then use the count to control another loop to:

Insert new "last" words at the end of the list.

For each one:

Call last() to establish the insertion point.

Call insert() to insert a "last" word.

~~~~~~~~~~~~~~~~~~~~~~~~~~~~~

# This program exercises lists.

# The following files must be in the same folder:

# abstractcollection.py

# abstractlist.py

# arraylist.py

# arrays.py

# linkedlist.py

# node.py

# input.txt - the input text file.

# Input: input.txt

# This file must be in the same folder.

# To keep things simple:

# This file contains no punctuation.

# This file contains only lowercase characters.

# Output: output.txt

# This file will be created in the same folder.

# All articles are removed.

# Certain prepositions are removed.

# Duplicate consecutive words are reduced to a single occurrence.

# Note: The words "first" and "last" are not reduced.

# Certain misspelled words are flagged.

# Occurrences of "first" are moved to the front of a line.

# Occurrences of "last" are moved to the end of a line.

from arraylist import ArrayList

from linkedlist import LinkedList

# Data:

articles = ArrayList(["a", "the"])

prepositions = LinkedList(["after", "before", "from", "in", "off", "on", "under", "out", "over", "to"])

misspellings = ["foriegn", "excede", "judgement", "occurrance", "preceed", "rythm", "thier", ]

inputFile = open("input.txt", "r")

outputFile = open("output.txt", "w")

FIRST = "first"

FLAG = "FLAG:"

LAST = "last"

# Processing:

# Part 1:

# Removes all items from the words list that are found in the removals list.

# Input:

# words - an ArrayList of words, no uppercase, no punctuation

# wordsIter - a list iterator for the words list

# removals - the list of words to remove

def removeItems(words, wordsIter, removals):

#

# Part 2:

# Removes extra occurrances of consecutive duplicate words from the words list.

# Note: It does not reduce the words "first" and "last".

# Input:

# words - an ArrayList of words, no uppercase, no punctuation

# wordsIter - a list iterator for the words list

def reduceDuplicates(words, wordsIter):

#

# Part 3:

# Flags certain misspelled words in the words list by inserting "FLAG:" before them.

# Input:

# words - an ArrayList of words, no uppercase, no punctuation

# wordsIter - a list iterator for the words list

# misspellings - the list of misspelled words to flag

def flagMisspelled(words, wordsIter, misspellings):

#

# Part 4:

# Move all occurrences of "first" to the front of the words list.

# Input:

# words - an ArrayList of words, no uppercase, no punctuation

# wordsIter - a list iterator for the words list

def moveFirstLit(words, wordsIter):

#

# Part 5:

# Move all occurrences of "last" to the end of the words list.

# Input:

# words - an ArrayList of words, no uppercase, no punctuation

# wordsIter - a list iterator for the words list

def moveLastLit(words, wordsIter):

#

def writeOutputLine(words):

outputLine = " ".join(words)

outputLine = outputLine + " "

print(outputLine, end="")

outputFile.write(outputLine)

# Main processing loop:

for line in inputFile:

words = ArrayList(line.split())

wordsIter = words.listIterator()

# Make no changes to blank lines:

if (len(words) == 0):

writeOutputLine(words)

continue

# Make no changes to comment lines:

if (words[0] == "#"):

writeOutputLine(words)

continue

# Remove articles:

removeItems(words, wordsIter, articles)

# Remove prepositions:

removeItems(words, wordsIter, prepositions)

# Reduce duplicate consecutive words to a single occurrence:

reduceDuplicates(words, wordsIter)

# Insert "FLAG:" before certain misspelled words:

flagMisspelled(words, wordsIter, misspellings)

# Move all occurrences of "first" to the front of the line:

moveFirstLit(words, wordsIter)

# Move all occurrences of "last" to the end of the line:

moveLastLit(words, wordsIter)

# Write output line:

writeOutputLine(words)

# Wrap-up

inputFile.close()

outputFile.close()

~~~~~~~~~~~~~~~~

"""

File: abstractcollection.py

Copyright 2015 by Ken Lambert

"""

class AbstractCollection(object):

"""An abstract collection implementation."""

# Constructor

def __init__(self, sourceCollection = None):

"""Sets the initial state of self, which includes the

contents of sourceCollection, if it's present."""

self._size = 0

self._modCount = 0

if sourceCollection:

for item in sourceCollection:

self.add(item)

# Accessor methods

def isEmpty(self):

"""Returns True if len(self) == 0, or False otherwise."""

return len(self) == 0

def __len__(self):

"""Returns the number of items in self."""

return self._size

def __str__(self):

"""Returns the string representation of self, using []

as delimiters."""

return "[" + ", ".join(map(str, self)) + "]"

def __eq__(self, other):

"""Returns True if self equals other,

or False otherwise.

Compares pairs of items in the two sequences

generated by the iterators on self and other."""

if self is other: return True

if type(self) != type(other) or \

len(self) != len(other):

return False

otherIter = iter(other)

for item in self:

if item != next(otherIter):

return False

return True

def __add__(self, other):

"""Returns a new collection containing the contents

of self and other."""

result = type(self)(self)

for item in other:

result.add(item)

return result

def count(self, item):

"""Returns the number of instance of item in self."""

counter = 0

for nextItem in self:

if item == nextItem: counter += 1

return counter

# These methods track and update the modCount, which is used to

# prevent mutations within the context of an iterator (for loop)

def getModCount(self):

"""Returns the number of modifications to the collection."""

return self._modCount

def incModCount(self):

"""Increments the number of modifications to the collection."""

self._modCount += 1

~~~~~~~~~~~~~~~~~~~~~~~

"""

File: abstractlist.py

Copyright 2015 by Ken Lambert

Common data and method implementations for lists.

"""

from abstractcollection import AbstractCollection

class AbstractList(AbstractCollection):

"""Represents an abstract list."""

def __init__(self, sourceCollection):

"""Maintains a count of modifications to the list."""

AbstractCollection.__init__(self, sourceCollection)

def index(self, item):

"""Precondition: item is in the list.

Returns the position of item.

Raises: ValueError if the item is not in the list."""

position = 0

for data in self:

if data == item:

return position

else:

position += 1

if position == len(self):

raise ValueError(str(item) + " not in list.")

def remove(self, item):

"""Precondition: item is in self.

Raises: ValueError if item in not in self.

Postcondition: item is removed from self."""

position = self.index(item)

self.pop(position)

def add(self, item):

"""Adds the item to the end of the list."""

self.insert(len(self), item)

def append(self, item):

"""Adds the item to the end of the list."""

self.add(item)

def listIterator(self):

"""Returns a list iterator."""

return AbstractList.ListIterator(self)

class ListIterator(object):

"""Represents the list iterator for an array list."""

def __init__(self, backingStore):

"""Sets the initial state of the list iterator."""

self._backingStore = backingStore

self._modCount = backingStore.getModCount()

self.first()

def first(self):

"""Returns the cursor to the beginning of the backing store.

lastItemPos is undefined."""

self._cursor = 0

self._lastItemPos = -1

def hasNext(self):

"""Returns True if the iterator has a next item or False otherwise."""

return self._cursor < len(self._backingStore)

def next(self):

"""Preconditions: hasNext returns True

The list has not been modified except by this iterator's mutators.

Returns the current item and advances the cursor to the next item.

Postcondition: lastItemPos is now defined.

Raises: ValueError if no next item.

AttributeError if illegal mutation of backing store."""

if not self.hasNext():

raise ValueError("No next item in list iterator")

if self._modCount != self._backingStore.getModCount():

raise AttributeError("Illegal modification of backing store")

self._lastItemPos = self._cursor

self._cursor += 1

return self._backingStore[self._lastItemPos]

def last(self):

"""Moves the cursor to the end of the backing store."""

self._cursor = len(self._backingStore)

self._lastItemPos = -1

def hasPrevious(self):

"""Returns True if the iterator has a previous item or False otherwise."""

return self._cursor > 0

def previous(self):

"""Preconditions: hasPrevious returns True

The list has not been modified except by this iterator's mutators.

Returns the current item and moves the cursor to the previous item."""

if not self.hasPrevious():

raise ValueError("No previous item in list iterator")

if self._modCount != self._backingStore.getModCount():

raise AttributeError("Illegal modification of backing store")

self._cursor -= 1

self._lastItemPos = self._cursor

return self._backingStore[self._lastItemPos]

def replace(self, item):

"""Preconditions: the current position is defined.

The list has not been modified except by this iterator's mutators.

Replaces the items at the current position with item."""

if self._lastItemPos == -1:

raise AttributeError("The current position is undefined.")

if self._modCount != self._backingStore.getModCount():

raise AttributeError("List has been modified illegally.")

self._backingStore[self._lastItemPos] = item

self._lastItemPos = -1

def insert(self, item):

"""Preconditions:

The list has not been modified except by this iterator's mutators.

Adds item to the end if the current position is undefined, or

inserts it at that position."""

if self._modCount != self._backingStore.getModCount():

raise AttributeError("List has been modified illegally.")

if self._lastItemPos == -1:

self._backingStore.add(item)

else:

self._backingStore.insert(self._lastItemPos, item)

self._lastItemPos = -1

self._modCount += 1

def remove(self):

"""Preconditions: the current position is defined.

The list has not been modified except by this iterator's mutators.

Pops the item at the current position."""

if self._lastItemPos == -1:

raise AttributeError("The current position is undefined.")

if self._modCount != self._backingStore.getModCount():

raise AttributeError("List has been modified illegally.")

item = self._backingStore.pop(self._lastItemPos)

# If the item removed was obtained via next, move cursor back

if self._lastItemPos < self._cursor:

self._cursor -= 1

self._modCount += 1

self._lastItemPos = -1

~~~~~~~~~~~~~~~~~~~~~~~~~

"""

File: arraylist.py

Copyright 2015 by Ken Lambert

"""

from arrays import Array

from abstractlist import AbstractList

class ArrayList(AbstractList):

"""Represents an array-based list."""

DEFAULT_CAPACITY = 10

def __init__(self, sourceCollection = None):

"""Sets the initial state of self, which includes the

contents of sourceCollection, if it's present."""

self._items = Array(ArrayList.DEFAULT_CAPACITY)

AbstractList.__init__(self, sourceCollection)

# Accessor methods

def __getitem__(self, i):

"""Precondition: 0 <= i < len(self)

Returns the item at position i.

Raises: IndexError if i is out of range."""

if i < 0 or i >= len(self):

raise IndexError("List index out of range")

return self._items[i]

def __iter__(self):

"""Supports iteration over a view of self."""

modCount = self.getModCount()

cursor = 0

while cursor < len(self):

yield self._items[cursor]

if modCount != self.getModCount():

raise AttributeError("Illegal modification of backing store")

cursor += 1

# Mutator methods

def clear(self):

"""Makes self become empty."""

self._size = 0

self._modCount = 0

self._items = Array(ArrayList.DEFAULT_CAPACITY)

self.incModCount()

def __setitem__(self, i, item):

"""Precondition: 0 <= i < len(self)

Replaces the item at position i.

Raises: IndexError if i is out of range."""

if i < 0 or i >= len(self):

raise IndexError("List index out of range")

self._items[i] = item

def _resize(self):

"""Private helper method to resize the array if necessary."""

temp = None

if len(self) == len(self._items):

temp = Array(2 * len(self._items))

elif len(self) <= len(self._items) // 4 and \

len(self._items) >= 2 * ArrayList.DEFAULT_CAPACITY:

temp = Array(len(self._items) // 2) # Derrf Seitz 11/06/15

if temp:

for i in range(len(self)):

temp[i] = self._items[i]

self._items = temp

def insert(self, i, item):

"""Inserts the item at position i."""

self._resize()

if i < 0: i = 0

elif i > len(self): i = len(self)

if i < len(self):

for j in range(len(self), i, -1):

self._items[j] = self._items[j - 1]

self._items[i] = item

self._size += 1

self.incModCount()

def pop(self, i = None):

"""Precondition: 0 <= i < len(self)

Removes and returns the item at position i.

Raises: IndexError if i is out of range."""

if i is None: # Derrf Seitz 11/06/15

i = len(self) - 1

if i < 0 or i >= len(self):

raise IndexError("List index out of range")

item = self._items[i]

for j in range(i, len(self) - 1):

self._items[j] = self._items[j + 1]

self._size -= 1

self._resize()

self.incModCount()

return item

~~~~~~~~~~~~~~~~~~~~~

"""

File: arrays.py

Copyright 2015 by Ken Lambert

An Array is a restricted list whose clients can use

only [], len, iter, and str.

To instantiate, use

= array(, )

The fill value is None by default.

"""

class Array(object):

"""Represents an array."""

def __init__(self, capacity, fillValue = None):

"""Capacity is the static size of the array.

fillValue is placed at each position."""

self._items = list()

for count in range(capacity):

self._items.append(fillValue)

def __len__(self):

"""-> The capacity of the array."""

return len(self._items)

def __str__(self):

"""-> The string representation of the array."""

return str(self._items)

def __iter__(self):

"""Supports iteration over a view of an array."""

return iter(self._items)

def __getitem__(self, index):

"""Subscript operator for access at index."""

return self._items[index]

def __setitem__(self, index, newItem):

"""Subscript operator for replacement at index."""

self._items[index] = newItem

~~~~~~~~~~~~~~~~~~~~~~

"""

File: linkedlist.py

Copyright 2015 by Ken Lambert

"""

from node import TwoWayNode

from abstractlist import AbstractList

class LinkedList(AbstractList):

"""A link-based list implementation."""

def __init__(self, sourceCollection = None):

"""Sets the initial state of self, which includes the

contents of sourceCollection, if it's present."""

# Uses a circular linked structure with a dummy header node

self._head = TwoWayNode()

self._head.previous = self._head.next = self._head

AbstractList.__init__(self, sourceCollection)

# Helper method returns node at position i

def _getNode(self, i):

"""Helper method: returns a pointer to the node at position i."""

if i == len(self) - 1:

return self._head.previous # Constant-time access to last item

probe = self._head.next

while i > 0:

probe = probe.next

i -= 1

return probe

#Accessor methods

def __iter__(self):

"""Supports iteration over a view of self."""

cursor = self._head.next

modCount = self.getModCount()

while cursor != self._head:

yield cursor.data

if modCount != self.getModCount():

raise AttributeError("Illegal modification of backing store")

cursor = cursor.next

def __getitem__(self, i):

"""Precondition: 0 <= i < len(self)

Returns the item at position i.

Raises: IndexError."""

if i < 0 or i >= len(self):

raise IndexError("List index out of range")

return self._getNode(i).data

# Mutator methods

def clear(self):

"""Makes self become empty."""

self._size = 0

self._modCount = 0

self._head = TwoWayNode()

self._head.previous = self._head.next = self._head

def __setitem__(self, i, item):

"""Precondition: 0 <= i < len(self)

Replaces the item at position i.

Raises: IndexError."""

if i < 0 or i >= len(self):

raise IndexError("List index out of range")

self._getNode(i).data = item

def insert(self, i, item):

"""Inserts the item at position i."""

if i < 0: i = 0

elif i > len(self): i = len(self)

theNode = self._getNode(i)

newNode = TwoWayNode(item, theNode.previous, theNode)

theNode.previous.next = newNode

theNode.previous = newNode

self._size += 1

self.incModCount()

def pop(self, i = None):

"""Precondition: 0 <= i < len(self).

Removes and returns the item at position i.

If i is None, i is given a default of len(self) - 1.

Raises: IndexError."""

if i == None: i = len(self) - 1

if i < 0 or i >= len(self):

raise IndexError("List index out of range")

theNode = self._getNode(i)

item = theNode.data

theNode.previous.next = theNode.next

theNode.next.previous = theNode.previous

self._size -= 1

self.incModCount()

return item

def listIterator(self):

"""Returns a list iterator."""

return LinkedList.ListIterator(self)

class ListIterator(object):

"""Represents the list iterator for linked list."""

def __init__(self, backingStore):

self._backingStore = backingStore

self._modCount = backingStore.getModCount()

self.first()

def first(self):

"""Returns the cursor to the beginning of the backing store."""

self._cursor = self._backingStore._head.next

self._lastItemPos = None

def hasNext(self):

"""Returns True if the iterator has a next item or False otherwise."""

return self._cursor != self._backingStore._head

def next(self):

"""Preconditions: hasNext returns True

The list has not been modified except by this iterator's mutators.

Returns the current item and advances the cursor to the next item."""

if not self.hasNext():

raise ValueError("No next item in list iterator")

if self._modCount != self._backingStore.getModCount():

raise AttributeError("Illegal modification of backing store")

self._lastItemPos = self._cursor

self._cursor = self._cursor.next

return self._lastItemPos.data

def last(self):

"""Moves the cursor to the end of the backing store."""

self._cursor = self._backingStore._head

self._lastItemPos = -1

def hasPrevious(self):

"""Returns True if the iterator has a previous item or False otherwise."""

return self._cursor.previous != self._backingStore._head

def previous(self):

"""Preconditions: hasPrevious returns True

The list has not been modified except by this iterator's mutators.

Returns the current item and moves the cursor to the previous item."""

if not self.hasPrevious():

raise ValueError("No previous item in list iterator")

self._cursor = self._cursor.previous

self._lastItemPos = self._cursor

return self._lastItemPos.data

def replace(self, item):

"""Preconditions: the current position is defined.

The list has not been modified except by this iterator's mutators.

Replaces the items at the current position with item."""

if self._lastItemPos is None:

raise AttributeError("The current position is undefined.")

if self._modCount != self._backingStore.getModCount():

raise AttributeError("List has been modified illegally.")

self._lastItemPos.data = item

self._lastItemPos = None

def insert(self, item):

"""Preconditions:

The list has not been modified except by this iterator's mutators.

Adds item to the end if the current position is undefined, or

inserts it at that position."""

if self._modCount != self._backingStore.getModCount():

raise AttributeError("List has been modified illegally.")

if self._lastItemPos is None:

self._backingStore.add(item)

else:

newNode = TwoWayNode(item, self._lastItemPos.previous, self._lastItemPos)

self._lastItemPos.previous.next = newNode

self._lastItemPos.previous = newNode

self._backingStore.incModCount()

self._backingStore._size += 1

self._lastItemPos = None

self._modCount += 1

def remove(self):

"""Preconditions: the current position is defined.

The list has not been modified except by this iterator's mutators.

Pops the item at the current position."""

if self._lastItemPos == None:

raise AttributeError("The current position is undefined.")

if self._modCount != self._backingStore.getModCount():

raise AttributeError("List has been modified illegally.")

item = self._lastItemPos.data

# If the item removed was obtained via previous, move cursor ahead

if self._lastItemPos == self._cursor:

self._cursor = self._cursor.next

self._lastItemPos.previous.next = self._lastItemPos.next

self._lastItemPos.next.previous = self._lastItemPos.previous

self._backingStore._size -= 1

self._backingStore.incModCount()

self._modCount += 1

self._lastItemPos = None

~~~~~~~~~~~~~~~~~~~~~

"""

File: node.py

Copyright 2015 by Ken Lambert

"""

class Node(object):

"""Represents a singly linked node."""

def __init__(self, data, next = None):

self.data = data

self.next = next

class TwoWayNode(Node):

"""Represents a doubly linked node."""

def __init__(self, data = None, previous = None, next = None):

Node.__init__(self, data, next)

self.previous = previous

~~~~~~~~~~~~~~~~~~

Input

# Articles:

this is the first test case

this is a second test case

this is neither the first nor a second test case

the a the a the a abc

the a the a the a

this is the last articles test case

# Certain prepositions:

the first dog ran after the deer but before the second dog

i will walk from here to over there

it is warm in here and cold out there

the rug is under the table and the table is over the rug

on off under over

this is the last prepositions test case

# Duplicate consecutive words (except "first" and "last"):

the boat had a blue blue hull

the boat had a blue very blue hull

the boat had a blue first blue hull

it is is the best way to go go

that that thats all folks

rolling rolling rolling on the river

the words first first and last last are intentionally not reduced

my my

# Certain misspelled words:

a foriegn concept that preceeds thier

a duplicated occurrance will excede the maximum allowed value

the judgement of thier souls

the music had a moving rythm

# Occurrences of "first" and "last":

the first shall be last

the last shall be first

multiple first place first place and last place last place winners and losers

first first first

last last

~~~~~~~~~~~~~~~~~~~~~~~~

Expected output

# Articles:

this is the first test case

this is a second test case

this is neither the first nor a second test case

the a the a the a abc

the a the a the a

this is the last articles test case

# Certain prepositions:

the first dog ran after the deer but before the second dog

i will walk from here to over there

it is warm in here and cold out there

the rug is under the table and the table is over the rug

on off under over

this is the last prepositions test case

# Duplicate consecutive words (except "first" and "last"):

the boat had a blue blue hull

the boat had a blue very blue hull

the boat had a blue first blue hull

it is is the best way to go go

that that thats all folks

rolling rolling rolling on the river

the words first first and last last are intentionally not reduced

my my

# Certain misspelled words:

a foriegn concept that preceeds thier

a duplicated occurrance will excede the maximum allowed value

the judgement of thier souls

the music had a moving rythm

# Occurrences of "first" and "last":

the first shall be last

the last shall be first

multiple first place first place and last place last place winners and losers

first first first

last last