How to compute word scores in Scrabble using MATLAB

Question

I have a homework program I have run into a problem with. We basically have to take a word (such as MATLAB) and have the function give us the correct score value for it usi

Answer 1

Building on Francis's post, what I would recommend you do is create a lookup array. You can certainly convert each character into its ASCII equivalent, but then what I would do is have an array where the input is the ASCII code of the character you want (with a bit of modification), and the output will be the point value of the character. Once you find this, you can sum over the points to get your final point score.

I'm going to leave out double points, double letters, blank tiles and that whole gamut of fun stuff in Scrabble for now in order to get what you want working. By consulting Wikipedia, this is the point distribution for each letter encountered in Scrabble.

• 1 point: A, E, I, O, N, R, T, L, S, U
• 2 points: D, G
• 3 points: B, C, M, P
• 4 points: F, H, V, W, Y
• 5 points: K
• 8 points: J, X
• 10 points: Q, Z

What we're going to do is convert your word into lower case to ensure consistency. Now, if you take a look at the letter a, this corresponds to ASCII code 97. You can verify that by using the double function we talked about earlier:

>> double('a')

97

As there are 26 letters in the alphabet, this means that going from a to z should go from 97 to 122. Because MATLAB starts indexing arrays at 1, what we can do is subtract each of our characters by 96 so that we'll be able to figure out the numerical position of these characters from 1 to 26.

Let's start by building our lookup table. First, I'm going to define a whole bunch of strings. Each string denotes the letters that are associated with each point in Scrabble:

string1point = 'aeionrtlsu';
string2point = 'dg';
string3point = 'bcmp';
string4point = 'fhvwy';
string5point = 'k';
string8point = 'jx';
string10point = 'qz';

Now, we can use each of the strings, convert to double, subtract by 96 then assign each of the corresponding locations to the points for each letter. Let's create our lookup table like so:

lookup = zeros(1,26);
lookup(double(string1point) - 96) = 1;
lookup(double(string2point) - 96) = 2;
lookup(double(string3point) - 96) = 3;
lookup(double(string4point) - 96) = 4;
lookup(double(string5point) - 96) = 5;
lookup(double(string8point) - 96) = 8;
lookup(double(string10point) - 96) = 10;

I first create an array of length 26 through the zeros function. I then figure out where each letter goes and assign to each letter their point values.

Now, the last thing you need to do is take a string, take the lower case to be sure, then convert each character into its ASCII equivalent, subtract by 96, then sum up the values. If we are given... say... MATLAB:

stringToConvert = 'MATLAB';
stringToConvert = lower(stringToConvert);
ASCII = double(stringToConvert) - 96;
value = sum(lookup(ASCII));

Lo and behold... we get:

value =

 10

The last line of the above code is crucial. Basically, ASCII will contain a bunch of indexing locations where each number corresponds to the numerical position of where the letter occurs in the alphabet. We use these positions to look up what point / score each letter gives us, and we sum over all of these values.

Part #2

The next part where double point values and double words come to play can be found in my other StackOverflow post here:

Calculate Scrabble word scores for double letters and double words MATLAB

Answer 2

Convert from string to ASCII:

>> myString = 'hello, world';
>> ASCII = double(myString)

ASCII =

   104   101   108   108   111    44    32   119   111   114   108   100

Sum up the values:

>> total = sum(ASCII)

total =

        1160

The MATLAB help for char() says (emphasis added):

S = char(X) converts array X of nonnegative integer codes into a character array. Valid codes range from 0 to 65535, where codes 0 through 127 correspond to 7-bit ASCII characters. The characters that MATLAB® can process (other than 7-bit ASCII characters) depend upon your current locale setting. To convert characters into a numeric array, use the double function.

ASCII chart here.