How to read just the powers from matlab output

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Ole
Ole 2020-6-18
评论： Image Analyst 2020-6-19
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

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采纳的回答

Ameer Hamza
Ameer Hamza 2020-6-19
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
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Ameer Hamza
Ameer Hamza 2020-6-19
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
Image Analyst 2020-6-19
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.

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更多回答（1 个）

Image Analyst
Image Analyst 2020-6-18
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')

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