COnvert x,y, time array into 3D matrix

2022 5 16
1 个回答
回答已采纳
更新时间：2022 5 17
2 次查看（30 天）

0 个投票

Hello,
I have an array of events captured at different pixels at different times. Each row has x, y and time values.
Here a simple example (x, y, time) with a short list of events:
1, 3, 2
1, 3, 2.3
1, 3, 2
1, 3, 2.1
1, 3, 2.4
4, 5, 1
4, 5, 1.4
4, 5 , 1
4, 5, 1.2
3 , 4, 1
3, 4, 1.4
3, 4 ,2
As can be seen, some times are duplicates for the same x,y.
I would like to create a 3D matrix made of x,y slices arranged according to time.
Duplicate times for the same pixel should be summed.
I would appreciate any suggestion.

请先登录，再回答此问题。

 采纳的回答

Star Strider
Star Strider 2022-5-16
Ran in:

0 个投票

Ran in:
Try this —
xyt = [1, 3, 2
1, 3, 2.3
1, 3, 2
1, 3, 2.1
1, 3, 2.4
4, 5, 1
4, 5, 1.4
4, 5 , 1
4, 5, 1.2
3 , 4, 1
3, 4, 1.4
3, 4 ,2];
[Uxytr,~,ix] = unique(xyt(:,3));
Out = accumarray(ix,(1:size(xyt,1))',[],@(x){[sum(xyt(x,[1 2]),1) unique(xyt(x,3))]})
Out = 7×1 cell array
{[ 11 14 1]} {[4 5 1.2000]} {[7 9 1.4000]} {[ 5 10 2]} {[1 3 2.1000]} {[1 3 2.3000]} {[1 3 2.4000]}
There are 7 unique times, and the (x,y) values for those times are summed, with the times themselves remaining unchanged.
.

4 个评论
显示 2更早的评论 隐藏 2更早的评论

Ilan
Ilan 2022-5-16
I realize that my question was not accurate enough:
I would like to create a 3D matrix in which each pixel (x,y) will contain the number of time occurences (say f) for that pixel. For example, the outcome from the example above should be for pix 1,3 time=2:
(x, y, f, t) 1, 3, 2, 2
for pix 4,5, t=1: 4, 5, 2, 1
for pix 4,5, t=1.2: 4, 5, 1, 1.2
I hope it is clear now.
Thanks.
Star Strider
Star Strider 2022-5-16
编辑：Star Strider 2022-5-16
Ran in:
Ran in:
‘I hope it is clear now.’
Not really. I have no idea what result you want.
I was going by: ‘Duplicate times for the same pixel should be summed.’
My code does exactly that.
EDIT — (16 May 2022 at 21:36)
To collect them together in cells is straightforward —
xyt = [1, 3, 2
1, 3, 2.3
1, 3, 2
1, 3, 2.1
1, 3, 2.4
4, 5, 1
4, 5, 1.4
4, 5 , 1
4, 5, 1.2
3 , 4, 1
3, 4, 1.4
3, 4 ,2];
[Uxytr,~,ix] = unique(xyt(:,3));
Out = accumarray(ix,(1:size(xyt,1))',[],@(x){xyt(x,:)})
Out = 7×1 cell array
{3×3 double } {[4 5 1.2000]} {2×3 double } {3×3 double } {[1 3 2.1000]} {[1 3 2.3000]} {[1 3 2.4000]}
Out{1}
ans = 3×3
4 5 1 4 5 1 3 4 1
Out{3}
ans = 2×3
4.0000 5.0000 1.4000 3.0000 4.0000 1.4000
Out{4}
ans = 3×3
1 3 2 1 3 2 3 4 2
.
Ilan
Ilan 2022-5-17
Thanks, this is what I wanted.
Star Strider
Star Strider 2022-5-17
As always, my pleasure!

请先登录，再进行评论。

更多回答（0 个）

类别

在 帮助中心 和 File Exchange 中查找有关 Creating and Concatenating Matrices 的更多信息

标签

Community Treasure Hunt

Find the treasures in MATLAB Central and discover how the community can help you!

Start Hunting!

Translated by