finding the mean and max
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suppose i have a matrix where the first column is x(:,1)=[ 1 1 1 2 2 1 1 3 1 ] and second column is x(:,2)=[ 2 3 2 4 6 9 7 8 9];
i want the output as y(:,1)=[ 1 2 3 ], y(:,2)=[ 9 6 8] and y(:,3)=[5.33 5 8];
the first column should be the values from first column of x reduced to a single value and in ascending order, the second column should be the highest number from the second column of x for a particular value in first input column. for ex. for all the 1's in first column of x should return one max value from the second column of x. the third column should contain the means of the second column of x for a particular value in first column of x. same example as given.
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Rik
2018년 11월 21일
편집: Rik
2018년 11월 21일
The first column you can achieve with unique, the second and third can be done with accumarray.
x=[ 1 1 1 2 2 1 1 3 1 ; 2 3 2 4 6 9 7 8 9]';
[col1,~,ind]=unique(x(:,1));
col2=accumarray(ind,x(:,2),[],@max);
col3=accumarray(ind,x(:,2),[],@mean);
y=[col1 col2 col3]
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Walter Roberson
2018년 11월 21일
the third output of unique gives you information about the original order .
Rik
2018년 11월 21일
This code produces the output like you describe. As Walter mentions (and as you can read in the doc of unique) the third output of the unique function returns the order so isequal(col1(ind),x(:,1)) returns true (barring any float rounding errors).
This means that this input will also work as intended:
x=[5 1 1 1 2 2 1 1 3 1 5;9 2 3 2 4 6 9 7 8 9 1]';
추가 답변 (1개)
Andrei Bobrov
2018년 11월 21일
편집: Andrei Bobrov
2018년 11월 21일
EDITED
>> XXX =[ 1 1 1 2 2 1 1 3 1 ; 2 3 2 4 6 9 7 8 9]'
XXX =
1 2
1 3
1 2
2 4
2 6
1 9
1 7
3 8
1 9
>> T = varfun(@(x)[max(x),mean(x)],array2table(XXX),'G',1);
out = T{:,[1,3]}
out =
1 9 5.3333
2 6 5
3 8 8
>>
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Andrei Bobrov
2018년 11월 21일
편집: Andrei Bobrov
2018년 11월 21일
I edited my answer, and you read the help about the MATLAB functions.
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