Assignment Probabilistic Text Generation with HashMap<K, V> and java.util.ArrayList<E>
You are to implement class RandomWriterWithHashMap.java that provides a random writing application using your HashMap class to store all possible seeds with its list of all possible following characters. We will be grading these live on Wed 4-May 10:00-10:50 in a Gould Simpson lab. If you cannot attend, email the program to your section leader. While testing your code, use any input file you want from Project Gutenberg.Use the your HashMap<K, V> class, java.util.ArrayList, and the following algorithm.
1. Read all file input into one big string (already done in RandomWriterWithHashMap.java)
2. Create a HashMap object that has all possible seeds of the given length as the key and an ArrayList<Character> of followers as the value. (You do this)
3. Pick a random seed from the original text. (already done in RandomWriterWithHashMap.java)
4. For each character you need to print (You do this)
· Randomly select one of the characters in the list of followers
· Print that random character
· Change the seed so the first character is gone and the just printed random character is appended
Here is a class that uses our familiar HashMap<K, V> class. It is intended to provide a start to the second part of the Project: RandomWriterWithHashMap. Method makeTheText reads all of the text from an input file into one big StringBuilder object. The StringBuilder class has the methods of the String class with a very efficient append method that we recommend you use. It also has code to get a random seed initially setRandomSeed. Feel free to use this code as a start http://www.cs.arizona.edu/people/mercer/Assignments/RandomWriterWithHashMap.java
// The beginning of the probabalistic text generation
public class RandomWriterWithHashMap {
public static void main(String[] args) {
// Assume there is a file named alice with the text: "Alice likes icy olives"
RandomWriterWithHashMap rw = new RandomWriterWithHashMap("alice", 2);
rw.printRandom(100);
}
private HashMap<String, ArrayList<Character> all;
private int seedLength;
private String fileName;
private StringBuilder theText;
private static Random generator;
private String seed;
public RandomWriterWithHashMap(String fileName, int seedLength) {
this.fileName = fileName;
this.seedLength = seedLength;
generator = new Random();
makeTheText();
setRandomSeed();
setUpMap(); // Algorithm to be considered during class
}
private void makeTheText() {
Scanner inFile = null;
try {
inFile = new Scanner(new File(fileName));
}
catch (FileNotFoundException e) {
e.printStackTrace();
}
theText = new StringBuilder();
while (inFile.hasNextLine()) {
theText = theText.append(inFile.nextLine().trim());
theText = theText.append(' ');
}
}
public void setRandomSeed() {
generator = new Random();
int start = generator.nextInt(theText.length() - seedLength);
seed = theText.substring(start, start + seedLength);
}
}
Consider algorithms for these two methods that use the put and get methods of HashMap
public void setUpMap() Example text: "Alice likes icy olives"
Added after lecture: Something like this was drawn on the whiteboard to explain what must be done in setUpMap. Using "Alice likes icy olives", create a HashMap<K, V> of seed/list mappings where the seed is a string of length 2 and the value mapped to each key is a list of ALL characters that follow that seed in the original text.
Seed / list toString()"Al" / [i]
"li" / [c, k ] // 'v' to be added
"ic" / [e, y]
"ce" / [ ] This ArrayList has one element (that you cannot see): a space ' '
"e " / [l]
" l" / [i]
"li" / "li" is already a key, add follower 'k' to the list already mapped to the key "li"
"ik" / [e]
"ke" / [s]
"es" / [ ] This ArrayList has one element: a space ' '. Another ' ' should be added later
"s " / [i]
" i" / [c]
"ic" / "ic" is already a key, add follower 'k' to the list already mapped to the key "ic"
... / ... 8 more possible seeds to map
public void printRandom(int n)
Use this algorithm from page 1
For each character you need to print
· Randomly select one of the characters in the list of followers (using current seed such as " i")
· Print that random character
· Change the seed so the first character is gone and the just printed random character is appended
Sample output (does it look like a bit like the original text?):
cy olikes ice lice lives ice likes icy olice lice
lives icy olives ice lice lives icy olives icy oli
Grading Criteria
___/ +20 Generates text that is gets closer to the original as the seed increases (subjective). For example when seed length = 2, a few words may appear; but when 12, some sentences appear close to the original text
· -20 If no text is generated with a printRandom(400) message
· -20 If you did not use a HashMap and the algorithm presented in the project that uses a Map to set up all seeds and the list of followers for each
· -19 If text has no apparent difference with different seed lengths or file input