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| author | wolffd |
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| date | Tue, 10 Feb 2015 15:05:51 +0000 |
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| 1 <html> | |
| 2 <head> | |
| 3 <title> | |
| 4 Netlab Reference Manual knnfwd | |
| 5 </title> | |
| 6 </head> | |
| 7 <body> | |
| 8 <H1> knnfwd | |
| 9 </H1> | |
| 10 <h2> | |
| 11 Purpose | |
| 12 </h2> | |
| 13 Forward propagation through a K-nearest-neighbour classifier. | |
| 14 | |
| 15 <p><h2> | |
| 16 Synopsis | |
| 17 </h2> | |
| 18 <PRE> | |
| 19 | |
| 20 [y, l] = knnfwd(net, x) | |
| 21 </PRE> | |
| 22 | |
| 23 | |
| 24 <p><h2> | |
| 25 Description | |
| 26 </h2> | |
| 27 <CODE>[y, l] = knnfwd(net, x)</CODE> takes a matrix <CODE>x</CODE> | |
| 28 of input vectors (one vector per row) | |
| 29 and uses the <CODE>k</CODE>-nearest-neighbour rule on the training data contained | |
| 30 in <CODE>net</CODE> to | |
| 31 produce | |
| 32 a matrix <CODE>y</CODE> of outputs and a matrix <CODE>l</CODE> of classification | |
| 33 labels. | |
| 34 The nearest neighbours are determined using Euclidean distance. | |
| 35 The <CODE>ij</CODE>th entry of <CODE>y</CODE> counts the number of occurrences that | |
| 36 an example from class <CODE>j</CODE> is among the <CODE>k</CODE> closest training | |
| 37 examples to example <CODE>i</CODE> from <CODE>x</CODE>. | |
| 38 The matrix <CODE>l</CODE> contains the predicted class labels | |
| 39 as an index 1..N, not as 1-of-N coding. | |
| 40 | |
| 41 <p><h2> | |
| 42 Example | |
| 43 </h2> | |
| 44 <PRE> | |
| 45 | |
| 46 net = knn(size(xtrain, 2), size(t_train, 2), 3, xtrain, t_train); | |
| 47 y = knnfwd(net, xtest); | |
| 48 conffig(y, t_test); | |
| 49 </PRE> | |
| 50 | |
| 51 Creates a 3 nearest neighbour model <CODE>net</CODE> and then applies it to | |
| 52 the data <CODE>xtest</CODE>. The results are plotted as a confusion matrix with | |
| 53 <CODE>conffig</CODE>. | |
| 54 | |
| 55 <p><h2> | |
| 56 See Also | |
| 57 </h2> | |
| 58 <CODE><a href="kmeans.htm">kmeans</a></CODE>, <CODE><a href="knn.htm">knn</a></CODE><hr> | |
| 59 <b>Pages:</b> | |
| 60 <a href="index.htm">Index</a> | |
| 61 <hr> | |
| 62 <p>Copyright (c) Ian T Nabney (1996-9) | |
| 63 | |
| 64 | |
| 65 </body> | |
| 66 </html> |