reorg and add code for second edition

12_knn/mnistHelper/loadMNISTImages.m

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+function images = loadMNISTImages(filename)
+%loadMNISTImages returns a 28x28x[number of MNIST images] matrix containing
+%the raw MNIST images
+
+fp = fopen(filename, 'rb');
+assert(fp ~= -1, ['Could not open ', filename, '']);
+
+magic = fread(fp, 1, 'int32', 0, 'ieee-be');
+assert(magic == 2051, ['Bad magic number in ', filename, '']);
+
+numImages = fread(fp, 1, 'int32', 0, 'ieee-be');
+numRows = fread(fp, 1, 'int32', 0, 'ieee-be');
+numCols = fread(fp, 1, 'int32', 0, 'ieee-be');
+
+images = fread(fp, inf, 'unsigned char');
+images = reshape(images, numCols, numRows, numImages);
+images = permute(images,[2 1 3]);
+
+fclose(fp);
+
+% Reshape to #pixels x #examples
+images = reshape(images, size(images, 1) * size(images, 2), size(images, 3));
+% Convert to double and rescale to [0,1]
+images = double(images) / 255;
+
+end

12_knn/mnistHelper/loadMNISTLabels.m

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+function labels = loadMNISTLabels(filename)
+%loadMNISTLabels returns a [number of MNIST images]x1 matrix containing
+%the labels for the MNIST images
+
+fp = fopen(filename, 'rb');
+assert(fp ~= -1, ['Could not open ', filename, '']);
+
+magic = fread(fp, 1, 'int32', 0, 'ieee-be');
+assert(magic == 2049, ['Bad magic number in ', filename, '']);
+
+numLabels = fread(fp, 1, 'int32', 0, 'ieee-be');
+
+labels = fread(fp, inf, 'unsigned char');
+
+assert(size(labels,1) == numLabels, 'Mismatch in label count');
+
+fclose(fp);
+
+end