问题
Before anyone asks, this is a repost of an earlier question, but I cannot delete it because it has answers, so I am modifying it so that hopefully Daniel R will answer it!
I have a grid of numbers and I want to read a string of numbers with strfind
in any of the 8 directions. The non-diagonal ones I have managed to get to work fine, it is the diagonal ones that I have been struggling with (except for downRight
which Daniel R helped me with earlier which I am very thankful for)!
Here is the code:
A = [5,16,18,4,9;
9,10,14,3,18;
2,7,9,11,21;
3,7,2,19,22;
4,9,10,13,8]
for r = 1:5
for diags = -5:5
downRight = strfind(diag(A,diags)', [10,9,19]);
if isempty(downRight) == 0;
rowOfFirstNum = downRight(1)+max(-diags,0);
columnOfFirstNum = downRight(1)+max(diags,0);
end
downLeft = strfind(diag(rot90(A),diags)', [11,2,9]);
if isempty(downLeft) == 0;
%rowOfFirstNum =
%columnOfFirstNum =
end
upLeft = strfind(diag(rot90(A,2),diags)', [19,9,10]);
if isempty(upLeft) == 0;
%rowOfFirstNum =
%columnOfFirstNum =
end
upRight = strfind(diag(rot90(A,3),diags)', [3,7,14,4]);
if isempty(upRight) == 0;
%rowOfFirstNum =
%columnOfFirstNum =
end
end
end
downRight
works, but I am not sure of how to get the others to work properly. Just to note, to test each direction the other 3 need to be commented out.
Thank you.
回答1:
A question personally addressing me, probably I must write an answer :)
Instead of implementing all 4 cases, I wrote a generic case. As you already noticed, the 4 cases can be produced using rot90
(rot90(X,0)
does nothing).
To get the indices, I created a meshgrid which contains row- and columnnumbers. Simply put it through the same process of rot90
and diag
, to see which index was moved to the position.
Finally, the outer loop (for r = 1:5
) simply repeats everything.
A = [5,16,18,4,9;
9,10,14,3,18;
2,7,9,11,21;
3,7,2,19,22;
4,9,10,13,8];
[col,row]=meshgrid(1:size(A,1));
x=[10,9,19];
% x=[11,2,9];
% x=[19,9,10];
% x=[3,7,14,4];
for diags = -5:5
for direction=0:3
loc = strfind(diag(rot90(A,direction),diags)', x);
if ~isempty(loc)
colT=diag(rot90(col,direction),diags);
rowT=diag(rot90(row,direction),diags);
rowOfFirstNum=rowT(loc)
columnOfFirstNum=colT(loc)
switch direction
case 0
%code for downRight
case 1
%code for downLeft
case 2
%code for upLeft
case 3
%code for upRight
end
end
end
end
来源:https://stackoverflow.com/questions/20551661/using-strfind-in-matlab-for-different-diagonal-directions-in-a-matrix