Project data

ex7/projectData.m

@@ -1,26 +1,36 @@
-function Z = projectData(X, U, K)
-%PROJECTDATA Computes the reduced data representation when projecting only 
-%on to the top k eigenvectors
-%   Z = projectData(X, U, K) computes the projection of 
-%   the normalized inputs X into the reduced dimensional space spanned by
-%   the first K columns of U. It returns the projected examples in Z.
-%
-
-% You need to return the following variables correctly.
-Z = zeros(size(X, 1), K);
-
-% ====================== YOUR CODE HERE ======================
-% Instructions: Compute the projection of the data using only the top K 
-%               eigenvectors in U (first K columns). 
-%               For the i-th example X(i,:), the projection on to the k-th 
-%               eigenvector is given as follows:
-%                    x = X(i, :)';
-%                    projection_k = x' * U(:, k);
-%
-
-
-
-
-% =============================================================
-
-end
+function Z = projectData(X, U, K)
+%PROJECTDATA Computes the reduced data representation when projecting only
+%on to the top k eigenvectors
+%   Z = projectData(X, U, K) computes the projection of
+%   the normalized inputs X into the reduced dimensional space spanned by
+%   the first K columns of U. It returns the projected examples in Z.
+%
+
+% You need to return the following variables correctly.
+Z = zeros(size(X, 1), K);
+
+% ====================== YOUR CODE HERE ======================
+% Instructions: Compute the projection of the data using only the top K
+%               eigenvectors in U (first K columns).
+%               For the i-th example X(i,:), the projection on to the k-th
+%               eigenvector is given as follows:
+%                    x = X(i, :)';
+%                    projection_k = x' * U(:, k);
+%
+
+U_reduce = U(:, 1:K);
+
+m = size(X, 1);
+n = size(X, 2);
+for i = 1:m
+  x = X(i, :)';
+  z = x' * U_reduce;
+
+  Z(i, :) = z;
+end
+
+assert(size(Z) == [m K]);
+
+% =============================================================
+
+end