Trouble getting data outside of parfor loop

3 次查看（过去 30 天）
John Doe
John Doe 2013-8-27
回答： John Doe 2013-10-28
Hello, I have a process that needs to be applied to a 90 trials of an 11 electrode signal. The result of each trial is in the form of 11 different matrices of a number of rows that varies between trials (no greater than 12). I'm having trouble getting those matrices stored without matlab saying it can't be done whilst using parfor.
I create giant matrices of zeros outside the loop that has enough space for the max possible number of rows. Then inside the loop I try and pass the data to giantmatrix(rowNumber:rowNumber + row length of data, :).
clear all
matlabpool;
load MIdata25;
fs = 160;
numberElectrodes = 11;
Left1 = zeros(15*length(squeeze(thinkLeft(1, :, 1))), 1312);
Left2 = zeros(15*length(squeeze(thinkLeft(1, :, 1))), 1312);
Left3 = zeros(15*length(squeeze(thinkLeft(1, :, 1))), 1312);
Left4 = zeros(15*length(squeeze(thinkLeft(1, :, 1))), 1312);
Left5 = zeros(15*length(squeeze(thinkLeft(1, :, 1))), 1312);
Left6 = zeros(15*length(squeeze(thinkLeft(1, :, 1))), 1312);
Left7 = zeros(15*length(squeeze(thinkLeft(1, :, 1))), 1312);
Left8 = zeros(15*length(squeeze(thinkLeft(1, :, 1))), 1312);
Left9 = zeros(15*length(squeeze(thinkLeft(1, :, 1))), 1312);
Left10 = zeros(15*length(squeeze(thinkLeft(1, :, 1))), 1312);
Left11 = zeros(15*length(squeeze(thinkLeft(1, :, 1))), 1312);
parfor currentTrial = 1:length(squeeze(thinkLeft(1, :, 1)))
currentTrial
chanNum = 0;
signalL=[];
signalTotal=[];
for currentElectrode = [2 6 8 9 11 13 14 16 20 41 42]
%matrix indexing stuff
signalTotal = [signalTotal; signalL3'];
end
x = %process applied to signalTotal
for currentElectrode = 1:11
xxl = zeros(numberElectrodes, length(signalL(1, :)));
for imfNo = 1:length(squeeze(x(1, :, 1)))
%matrix re-indexing stuff
end
if currentElectrode == 1
Left1(((currentTrial-1)*15)+1:((currentTrial-1)*15)+length(xxl(:, 1)), :) = xxl;
elseif currentElectrode == 2
Left2(((currentTrial-1)*15)+1:((currentTrial-1)*15)+length(xxl(:, 1)), :) = xxl;
elseif currentElectrode == 3
Left3(((currentTrial-1)*15)+1:((currentTrial-1)*15)+length(xxl(:, 1)), :) = xxl;
elseif currentElectrode == 4
Left4(((currentTrial-1)*15)+1:((currentTrial-1)*15)+length(xxl(:, 1)), :) = xxl;
elseif currentElectrode == 5
Left5(((currentTrial-1)*15)+1:((currentTrial-1)*15)+length(xxl(:, 1)), :) = xxl;
elseif currentElectrode == 6
Left6(((currentTrial-1)*15)+1:((currentTrial-1)*15)+length(xxl(:, 1)), :) = xxl;
elseif currentElectrode == 7
Left7(((currentTrial-1)*15)+1:((currentTrial-1)*15)+length(xxl(:, 1)), :) = xxl;
elseif currentElectrode == 8
Left8(((currentTrial-1)*15)+1:((currentTrial-1)*15)+length(xxl(:, 1)), :) = xxl;
elseif currentElectrode == 9
Left9(((currentTrial-1)*15)+1:((currentTrial-1)*15)+length(xxl(:, 1)), :) = xxl;
elseif currentElectrode == 10
Left10(((currentTrial-1)*15)+1:((currentTrial-1)*15)+length(xxl(:, 1)), :) = xxl;
elseif currentElectrode == 11
Left11(((currentTrial-1)*15)+1:((currentTrial-1)*15)+length(xxl(:, 1)), :) = xxl;
end
end
midpointL(currentTrial, :) = length(xxl(:, 1));
end
With matlab showing problems with Left1-9, though it seems fine with midpointL.
  1 个评论
Walter Roberson
Walter Roberson 2013-8-27
Try replacing the length(xx1(:,1)) with numberElectrodes since you built xx1 with numberElectrodes as the first dimension.

请先登录，再进行评论。

请先登录，再回答此问题。

采纳的回答

John Doe
John Doe 2013-10-28
The answer to this was that matlab does not like "parfor variable +/- integer" as it thinks it'll be used to reference a previous loop which it can't do in parallel. In this case it's the variable CurrentTrial. Creating a 3d matrix instead of a 2d one with CurrentTrial used to define the first column solved it.

更多回答（1 个）

Matt J
Matt J 2013-8-27
编辑：Matt J 2013-8-28
I create giant matrices of zeros outside the loop that has enough space for the max possible number of rows. Then inside the loop I try and pass the data to giantmatrix.
A better idea would probably be to dispense with Left1...9 and instead store the results (of different sizes) in a 90x11 cell array. Then combine them after the loops end as needed.
N=length(squeeze(thinkLeft(1, :, 1)));
LoopData=cell(N, 11);
parfor currentTrial = 1:N
for currentElectrode = 1:11
xxl = ...;
LoopData{currentTrial,currentElectrode}=xxl;
end
end
Now you can combine all the different xxl in LoopData using cell2mat() or similar...

类别

在 Help Center 和 File Exchange 中查找有关 Matrix Indexing 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