how does the vector extration operated in the following commands
1 Ansicht (letzte 30 Tage)
Ältere Kommentare anzeigen
Fan Yang
am 4 Aug. 2018
Kommentiert: Fan Yang
am 4 Aug. 2018
a=[3 1 2 12 4]
x=(2:end)
why does x contain 1, 2, 12, and 4?
0 Kommentare
Akzeptierte Antwort
Walter Roberson
am 4 Aug. 2018
If you meant x=a(2:end) then that would contain 1, 2, 12, and 4.
When used in a single index, "end" stands in for numel() of the array it is being applied to. Your a is length 5, so a(2:end) stands in for a(2:numel(a)) which is a(2:5) . So the second, third, fourth, and fifth elements of a would be selected.
If you were using two dimensional indexing, like
b = [3 1 2 12 14; -4 9 3 8 2]
b(:,2:end)
then "end" stands in for size() of the index in that position. So b(:,2:end) would stand in for b(:, 2:size(b,2)) which would be b(:, 2:5) . The : in the first position would stand in for 1:end, as if you had written b(1:end, 2:end), so that would be b(1:size(b,1), 2:size(b,2)) which would be b(1:2, 2:5) and would give columns 2, 3, 4, 5 of both rows of b.
Weitere Antworten (0)
Siehe auch
Kategorien
Mehr zu Matrix Indexing 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!