How to read just the powers from matlab output

How to read/print the powers from the matlab output function coeffs ?

l^4*w^3*z^1 and l^4*w^3

I would like to obtain numbers 341 and 340 from the above sequence.

[r, t] = coeffs(10*z^2*w^4 + 5*w^2*l^2 + 2*z^6)

t =
 
[ l^2*w^2, w^4*z^2, z^6]

% 220 402 006

Answer 1

[Ameer Hamza]

How are the terms separated? If separated using '+' operator, then try the following code

str = '10*z^2*w^4 + 5*w^2*l^2 + 2*z^6';
patterns = {'w\^([0-9]*)', 'l\^([0-9]*)', 'z\^([0-9]*)'};
tokens = cellfun(@(p) {regexp(strsplit(str, '+'), p, 'tokens')}, patterns);
y = cellfun(@(token) {cellfun(@helperFun, token)}, tokens);
y = reshape(cell2mat(y(:)), 1, []);

function y = helperFun(x)
    if ~isempty(x)
        y = str2double(x{1}{1});
    else
        y = 0;
    end
end

Result

>> y
y =
     4     0     2     2     2     0     0     0     6

[Image Analyst]

He said he wants "just the powers" so I assume he wants just the numbers that are powers (exponents) meaning the numbers after the carets ^.

[Ameer Hamza]

But OP mentioned for the first example that "I would like to obtain numbers 341 and 340 from the above sequence." and for the second example

[ l^2*w^2, w^4*z^2, z^6]
% 220 402 006

so I guessed that the absent variables would have 0 exponents.

[Image Analyst]

Oh, that could be another interpretation. I was wondering how he got those numbers. Let's hope for clarification from Ole. It seems he has totally forgotten about this question he posted.

Answer 2

[Image Analyst]

Here's one way, using isstrprop():

chr = 'l^4*w^3*z^1 and 8^4*w^3' % Create test character array.
mask = isstrprop(chr,'digit') % Get locations of numbers
caretLocations = chr == '^'
caretLocations = [false, caretLocations(1:end-1)] % Shift to the right.
mask = mask & caretLocations
chr(~mask) = ' '
numbers = sscanf(chr, ' %f')

[Image Analyst]

Results:

numbers =

4

3

1

4

3