Finding if a number repeats in a single row

Question

Max 2015-10-24

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此问题的直接链接

https://ww2.mathworks.cn/matlabcentral/answers/250826-finding-if-a-number-repeats-in-a-single-row

回答： Star Strider 2015-10-24

How do I create a script that checks if a number comes up more than once in a single row. For example, lets say we have a single row x=[-1,0,1,2,3,4,5,1] Is there a script that starts at say (i=1 and ends at i=final number of x) that starts at i=1 and checks if -1 comes up again in x if it doesn't goes to i=2 and checks if 0 comes up in x again if it doesn't it then goes to i=3 and checks if 1 comes up in x again which it does then stops at that point which is i=3. An additional example if this didn't make sense would be take y=[0,4,5,6,1,2,2,9,12,15] it starts at i=1 to check if 0 comes up again which it doesnt, then goes to i=2 and checks if 4 comes up again which it doesnt then i=3 if 5 comes up again which it doesnt then i=4 to check if 6 comes up again which it doesnt then i=5 to check if 1 comes up again which it doesnt then i=6 to check if 2 comes up again which it does. I then stops at i=6.

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Answer 1

Star Strider 2015-10-24

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https://ww2.mathworks.cn/matlabcentral/answers/250826-finding-if-a-number-repeats-in-a-single-row#answer_197198

在 MATLAB Online 中打开

I’m not certain exactly what you want. See if this works:

x=[-1,0,1,2,3,4,5,1];
[Ux,xa,xc] = unique(x,'stable');                        % Unique Numbers
fr_x = accumarray(xc,1);                                % Frequencies
Result_x = find(fr_x > 1)                               % First Position Of First Repeating Number
y=[0,4,5,6,1,2,2,9,12,15];
[Uy,ya,yc] = unique(y,'stable');                        % Same For ‘,y’
fr_y = accumarray(yc,1);
Result_y = find(fr_y > 1)
Result_x =
     3
Result_y =
     6