Extract first and last row of each subarray in a cell array

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JIAN-HONG YE ZHU
JIAN-HONG YE ZHU 2023-4-10
评论： Walter Roberson 2023-4-10
Hello, if I have a 7×1 cell array, how could I extract the first and last row of each sub-array.
So if my cell looks like this:
I would like to end up with a matrix that looks like this (I put spaces so it is more clear what I want from each sub-array) :
50.0000 30.0000
50.4897 31.9177
61.0370 51.2245
61.5267 53.1422
61.5267 65.1422
60.6073 66.8252
58.5037 67.4803
54.2273 68.6080
52.1029 69.2125
51.0000 71.0000
I included the 7x1 cell array file.
Thanks.

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采纳的回答

Paul
Paul 2023-4-10
编辑：Paul 2023-4-10
Ran in:
I think this works even if the first and last row of a cell are identical.
load(websave('cellArray.mat','https://www.mathworks.com/matlabcentral/answers/uploaded_files/1350539/cellArray.mat'));
out = cellfun(@(x) x(1:max(end-1,1):end,:),group1,'UniformOutput',false)
out = 7×1 cell array
{[ 50 30]} {2×2 double } {2×2 double } {[60.6073 66.8252]} {2×2 double } {[52.1029 69.2125]} {[ 51 71]}
out = vertcat(out{:})
out = 10×2
50.0000 30.0000 50.4897 31.9177 61.0370 51.2245 61.5267 53.1422 61.5267 65.1422 60.6073 66.8252 58.5037 67.4803 54.2273 68.6080 52.1029 69.2125 51.0000 71.0000
  1 个评论
Walter Roberson
Walter Roberson 2023-4-10
By the way, @Paul the websave() work-around is no longer generally needed. If you use the attachment toolbar icon, then the second tab, "Link from this thread" allows you to select items that other people have attached in the Question, a makes them available for the Run facility (without duplicating them -- it makes links internally.)

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更多回答（2 个）

Walter Roberson
Walter Roberson 2023-4-10
output = cellfun(@(C) C(unique([1, end]), :), YourCellArray, 'uniform', 0)
The unique() is there to prevent it from accidentally copying data when there happens to be only one row in a cell
the cyclist
the cyclist 2023-4-10
Ran in:
I believe this does what you want.
load cellArray.mat
c = cellfun(@(x)unique(x([1 end],:),"row"),group1,"UniformOutput",false);
m = cell2mat(c)
m = 10×2
50.0000 30.0000 50.4897 31.9177 61.0370 51.2245 61.5267 53.1422 61.5267 65.1422 60.6073 66.8252 54.2273 68.6080 58.5037 67.4803 52.1029 69.2125 51.0000 71.0000
The cells that have one row make this a bit tricky. The first and last row of a one-row are the same, but it looks like you don't want it listed twice. So, I use "unique" to get only one of them. But, this algorithm will fail if the first and last row of a multi-row array are identical.

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