Description
1 Introduction
A word cloud is a visual representation of the text contained in a file, where the importance of each word is
shown with font size or color. For example, the frequency of the word (how often it occurs in the file) can be
associated with a font size and color, where larger fonts would represent words that occurs more often. The
word cloud for the text of this assignment is given below. For this lab you will write a program to determine
the word frequency of a text file, then use another program to create the word cloud (saved as a png file).
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Word cloud for the text in this document.
1.1 Word Frequency
We are interested in determining the word frequency (a count of the number of times a word is used) of
a text file. The program will first prompt the user for the name of a text file. If the file does not exist,
re-prompt until a legitimate file name is provided. Afterwards, read the file and process every word in the
file. Once the the frequency has been determined, print the number of words found to the screen. Then
prompt the user for an output file name and write the word frequencies to the file. The words must be sorted
in descending order based on the frequencies. For example, assume the user enters roll.txt for the text
file name and wants to create roll.frq as the frequency file. The following would be the result.
screen output roll.frq
✷ Terminal ✷✷
> ./lab6
Read text file
Enter the name of the file -> roll.txt
roll.txt has 1237 unique words
———————————————–
Create frequency file
Enter the name of the file -> roll.frq
Creating roll.frq … done!
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.
.
.
The word frequency file should contain one line per unique word found, where each line has the word, a
space, then the count. The first 10 lines of the roll.frq file are shown above.
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1.2 Word Frequency
The word cloud can be created using the frequency file described in the previous subsection. The program
cloudy.R will take a word frequency file and generate a png (graphics format) file. The eog command will
display the image to the screen.
screen output roll.png
✷ Terminal ✷✷
> /var/tmp/cloudie.R roll.frq roll.png
roll.png created
> eog roll.png
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2 Program Design
Although word frequency is a simple task to describe, dealing with C-strings (as you found-out on the test)
can be problematic. Your program must adhere to the following program design requirements.
2.1 A struct and Arrays for Character Counts
As characters are read from the file, you will keep track of the number of times a word appears in the file.
The word list should store two items per element, the word (C-string) and the count. Use the following
struct to store the two items.
1 # include < iostream >
2 # include < fstream >
3 // maximum string size
4 # define MAX_STRING_SIZE 20
5 // maximum word list size
6 # define MAX_LIST_SIZE 5000
7 using namespace std ;
8
9 // === data type to store a word and its count ==================
10 struct WordFreq
11 {
12 // constructor for the WordFreq type , just a good idea …
13 WordFreq (){ word [0] = ’\0 ’; count = 0; }
14
15 // data members
16 char word [ MAX_STRING_SIZE ]; /// < the word
17 int count ; /// < the word frequency
18 };
As seen above, the struct definition should be placed immediately after the using namespace std; statement in your program. This placement will allow it to be used everywhere in your program. Note, the
struct includes a constructor that initializes each instance of the type (a good idea for C-strings). You
should then create an array for the unique words in the main as follows.
1 WordFreq list [ MAX_LIST_SIZE ]; // list of unique words
2 int num = 0; // number of unique words
2.2 Reading the File and Processing Words
Reading the file and processing words must be done in a separate function. The function will first attempt
to open the file and if the file does not exist, then return false and read another file name from the user.
Once a valid file name has been entered, read each character one at a time from the file and build strings.
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Consider the characters in the file as a long array that your program will process one element at a time.
text file
this is, a
gr8 lab. OK?
array representation
’t’’h’’i’’s’’ ’’i’’s’’,’’ ’’a’’\n’’g’’r’’8’’ ’’l’’a’’b’’.’’ ’’O’’K’’?’’\n’
Scanning the array from left to right (which is how characters are read from the file) a candidate word has
been read once a word delineator is encountered. For example, a space ’ ’ is a word delineator; therefore,
the string “this” in the array above is a candidate word. Other delineators include commas, periods, new
lines, etc… (you need to develop a complete list). Once a candidate word is encountered, then determine if
is it a word. For this lab assume any string that consists only of letters is a word. For example “gr8” is not
a word, but “OK” would be a word for this lab. The following code segment will read characters from a file
and produce candidate words. Note, you need to add to the set of word delineators.
1 fstream inFile ( fileName , ios :: in ); // / < fstream for file
2 // if the file could not be opened , return false
3 if( inFile . fail ()) return false;
4
5 char str [ MAX_STRING_SIZE ]; // / < current string
6 int n; // / < length of string
7 char ch ; // / < current character
8
9 // initialize string
10 str [0] = ’\0 ’;
11 // get a character from the file
12 ch = inFile . get ();
13 while (! inFile . eof ())
14 {
15 // if ch is word delineator ( you should add to the OR statement)
16 // then you have a candidate word
17 if( ch == ’ ’ || ch == ’\n ’)
18 {
19 // if string is a word , add to list
20 if( isWord ( str ))
21 addWordToList( str , list , num );
22
23 // reset the string
24 str [0] = ’\0 ’;
25 }
26 else
27 {
28 // add new character to end of the string , if there is space
29 n = strlen ( str );
30 if( n < MAX_STRING_SIZE – 1)
31 {
32 str [n ] = tolower( ch );
33 str [n + 1] = ’\0 ’;
34 }
35 }
36 ch = inFile . get ();
37 }
38 inFile . close ();
39 return true;
There are two additional functions referenced in the code segment above that you must write.
• isWord(char str[]) returns true if the C-string str is a word, otherwise it returns false
• addWordToList(char str[], WordFreq list[], int& num) updates the word list list with the Cstring str, which is similar to addCharToList from lab 5.
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2.3 Other Functions and Writing to a File
Similar to the previous lab, there are several other functions you will need to write for this lab assignment.
You will write a function to sort the word list based on the frequencies and a function for writing the word
list to a file. Note, writing to a file is the same as writing to the screen. The following is a code segment
that opens a file and writes the word list to the file.
1 char fileName[ MAX_STRING_SIZE ];
2 fstream outFile;
3
4 do
5 {
6 readFileName( fileName);
7 outFile. open ( fileName , ios :: out );
8 }
9 while ( outFile. fail ());
10
11 for( int i = 0; i < num ; i ++)
12 outFile << list [i ]. word << ’ ’ << list [i ]. count << ’\n ’;
13
14 outFile. close ();
3 Programming Points
You must adhere to all of the following points to receive credit for this lab assignment.
1. Create a directory Lab6 off of your CSC112 directory to store your program in a file called lab6.cpp
2. Your program must be modular in design.
3. Your main function can only consist of variable declarations, function calls, and control structures (no
input or output in the main function).
4. Your program must compile cleanly, no errors or warnings are allowed.
5. Your program must adhere to documentation style and standards. Don’t forget function headers and
variable declarations.
6. Turn-in (copy to your Grade/Lab6 directory) a word cloud png (image file) of the wakebaseball.twt
text file, which is available from the course web-site.
7. Turn-in a print-out of your program source code (lab6.cpp). In addition, copy your program source
code to your Grade/Lab6 directory.
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