详尽的渠道/特征选择降低维度(Dimensionality reduction in exhaustive channel/feature selection)

详尽的渠道/特征选择降低维度(Dimensionality reduction in exhaustive channel/feature selection)

我的数据包括16channelsx128samplesx400trials。 我想在这个数据集中执行详尽的频道选择。 我应该在哪里应用PCA？

unsortedChannelIndices = [1:16] sortedChannelIndices = []; %Option 1 reducedData = PCA(data, classIndeces) for chIdx = 1:length(unsortedChannelIndices) for c=1:length(unsortedChannelIndices) thisChannel = unsortedChannelIndices(c) thisChannelSet = [sortedChannelIndices, thisChannel]; %Option 1 thisData = reducedData(thisChannelSet,:,:); %Option 2 thisData = PCA(data(thisChannelSet, classIndeces) thisPerformance(c) = eval_perf(thisData);%crossvalidation end [performance(chIdx),best] = max(thisPerformance); sortedChannelIndices = [sortedChannelIndices,unsortedChannelIndices(best)]; unsortedChannelIndices(best) = []; end

My data consist of 16channelsx128samplesx400trials. I wanna perform exhaustive channel selection in this dataset. Where should I apply PCA?

unsortedChannelIndices = [1:16] sortedChannelIndices = []; %Option 1 reducedData = PCA(data, classIndeces) for chIdx = 1:length(unsortedChannelIndices) for c=1:length(unsortedChannelIndices) thisChannel = unsortedChannelIndices(c) thisChannelSet = [sortedChannelIndices, thisChannel]; %Option 1 thisData = reducedData(thisChannelSet,:,:); %Option 2 thisData = PCA(data(thisChannelSet, classIndeces) thisPerformance(c) = eval_perf(thisData);%crossvalidation end [performance(chIdx),best] = max(thisPerformance); sortedChannelIndices = [sortedChannelIndices,unsortedChannelIndices(best)]; unsortedChannelIndices(best) = []; end

最满意答案

PCA或任何降维技术应与将要分析的数据一起应用。 如果我们评估对应于较少通道（例如1：4）的子集的性能，则应在该数据中应用任何降维技术（PCA（数据（[1：4），：，:)。因此，选项2是正确的选择。

The PCA or any dimensionality reduction technique should be applied with the data that will be analyzed. If we wana evaluate the performance of the subset corresponding to less channels (eg 1:4), any dimensionality reduction technique should be applied in this data (PCA(data([1:4),:,:). Hence, Option 2 is the correct option.