finding the mean and max
1 visualizzazione (ultimi 30 giorni)
Mostra commenti meno recenti
johnson saldanha
il 21 Nov 2018
Modificato: Andrei Bobrov
il 21 Nov 2018
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.
0 Commenti
Risposta accettata
Rik
il 21 Nov 2018
Modificato: Rik
il 21 Nov 2018
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]
3 Commenti
Walter Roberson
il 21 Nov 2018
the third output of unique gives you information about the original order .
Rik
il 21 Nov 2018
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]';
Più risposte (1)
Andrei Bobrov
il 21 Nov 2018
Modificato: Andrei Bobrov
il 21 Nov 2018
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
>>
2 Commenti
Andrei Bobrov
il 21 Nov 2018
Modificato: Andrei Bobrov
il 21 Nov 2018
I edited my answer, and you read the help about the MATLAB functions.
Vedere anche
Categorie
Scopri di più su Creating and Concatenating Matrices in Help Center e File Exchange
Community Treasure Hunt
Find the treasures in MATLAB Central and discover how the community can help you!
Start Hunting!