Count number of times value appears in column
12 Ansichten (letzte 30 Tage)
Ältere Kommentare anzeigen
Emma Kuttler
am 22 Nov. 2019
Bearbeitet: Image Analyst
am 23 Nov. 2019
I have a 1000x296 matrix called FinalRanking. The possible values in each cell are between 1 and 296, integers.
I want to count the number of times each number, 1-296, appears in each column, and return this as a 296x296 matrix, lets call it counter.
so for example Counter(1,1) has the value of the number of time 1 appears in Column 1 of FinalRanking.
or Counter(12, 57) returns the value of the number of times 12 appears in Column 57 of FinalRanking.
How would I do this? I'm assuming i need nested for loops. Thanks!
0 Kommentare
Akzeptierte Antwort
the cyclist
am 22 Nov. 2019
Bearbeitet: the cyclist
am 22 Nov. 2019
% Parameterize the max value, for convenience
V = 296;
% Some simulated data
FinalRanking = randi(V,1000,V);
% Preallocate the counter array
counter = nan(V,V);
% Loop over the columns, and count the number of times each value appears
for nc = 1:V
counter(:,nc) = histcounts(FinalRanking(:,nc),[1:V Inf]);
end
Weitere Antworten (2)
Andrei Bobrov
am 22 Nov. 2019
Bearbeitet: Andrei Bobrov
am 22 Nov. 2019
out = histc(FinalRanking,1:296);
4 Kommentare
Andrei Bobrov
am 22 Nov. 2019
"If performance is a problem due to a large number of columns in the matrix, then consider continuing to use histc for the column-wise bin counts." - wrote The Mathworks.
Image Analyst
am 22 Nov. 2019
Try this:
edges = 1 : 297;
FinalRanking = randi(296, 1000, 296);
counter = zeros(296, 296);
for col = 1 : size(FinalRanking, 2)
counter(:, col) = histcounts(FinalRanking(:, col), edges);
end
imshow(counter, [], 'ColorMap', hsv(256));
axis('on', 'image');
colorbar;
impixelinfo;
2 Kommentare
Image Analyst
am 23 Nov. 2019
Bearbeitet: Image Analyst
am 23 Nov. 2019
Yes for x. But along the y axis are the histogram bins. The value, "z" value if you want to think of it like that, is the count. But the actual distance/location along the y axis is the bin number, not the "number of occurrences" (counts).
fontSize = 20; % Whatever.
xlabel('Column', 'FontSize', fontSize);
ylabel('Number (i.e., histogram bin)', 'FontSize', fontSize);
Siehe auch
Kategorien
Mehr zu Orange finden Sie in Help Center und File Exchange
Community Treasure Hunt
Find the treasures in MATLAB Central and discover how the community can help you!
Start Hunting!