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<html><head><title>dlib C++ Library - assignment_learning_ex.cpp</title></head><body bgcolor='white'><pre> |
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<font color='#009900'>// The contents of this file are in the public domain. See LICENSE_FOR_EXAMPLE_PROGRAMS.txt |
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</font><font color='#009900'>/* |
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This is an example illustrating the use of the dlib machine learning tools for |
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learning to solve the assignment problem. |
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Many tasks in computer vision or natural language processing can be thought of |
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as assignment problems. For example, in a computer vision application where |
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you are trying to track objects moving around in video, you likely need to solve |
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an association problem every time you get a new video frame. That is, each new |
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frame will contain objects (e.g. people, cars, etc.) and you will want to |
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determine which of these objects are actually things you have seen in previous |
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frames. |
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The assignment problem can be optimally solved using the well known Hungarian |
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algorithm. However, this algorithm requires the user to supply some function |
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which measures the "goodness" of an individual association. In many cases the |
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best way to measure this goodness isn't obvious and therefore machine learning |
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methods are used. |
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The remainder of this example will show you how to learn a goodness function |
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which is optimal, in a certain sense, for use with the Hungarian algorithm. To |
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do this, we will make a simple dataset of example associations and use them to |
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train a supervised machine learning method. |
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Finally, note that there is a whole example program dedicated to assignment |
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learning problems where you are trying to make an object tracker. So if that is |
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what you are interested in then take a look at the <a href="learning_to_track_ex.cpp.html">learning_to_track_ex.cpp</a> |
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example program. |
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*/</font> |
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<font color='#0000FF'>#include</font> <font color='#5555FF'><</font>iostream<font color='#5555FF'>></font> |
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<font color='#0000FF'>#include</font> <font color='#5555FF'><</font>dlib<font color='#5555FF'>/</font>svm_threaded.h<font color='#5555FF'>></font> |
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<font color='#0000FF'>using</font> <font color='#0000FF'>namespace</font> std; |
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<font color='#0000FF'>using</font> <font color='#0000FF'>namespace</font> dlib; |
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<font color='#009900'>// ---------------------------------------------------------------------------------------- |
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</font> |
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<font color='#009900'>/* |
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In an association problem, we will talk about the "Left Hand Set" (LHS) and the |
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"Right Hand Set" (RHS). The task will be to learn to map all elements of LHS to |
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unique elements of RHS. If an element of LHS can't be mapped to a unique element of |
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RHS for some reason (e.g. LHS is bigger than RHS) then it can also be mapped to the |
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special -1 output, indicating no mapping to RHS. |
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So the first step is to define the type of elements in each of these sets. In the |
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code below we will use column vectors in both LHS and RHS. However, in general, |
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they can each contain any type you like. LHS can even contain a different type |
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than RHS. |
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*/</font> |
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<font color='#0000FF'>typedef</font> dlib::matrix<font color='#5555FF'><</font><font color='#0000FF'><u>double</u></font>,<font color='#979000'>0</font>,<font color='#979000'>1</font><font color='#5555FF'>></font> column_vector; |
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<font color='#009900'>// This type represents a pair of LHS and RHS. That is, sample_type::first |
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</font><font color='#009900'>// contains a left hand set and sample_type::second contains a right hand set. |
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</font><font color='#0000FF'>typedef</font> std::pair<font color='#5555FF'><</font>std::vector<font color='#5555FF'><</font>column_vector<font color='#5555FF'>></font>, std::vector<font color='#5555FF'><</font>column_vector<font color='#5555FF'>></font> <font color='#5555FF'>></font> sample_type; |
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<font color='#009900'>// This type will contain the association information between LHS and RHS. That is, |
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</font><font color='#009900'>// it will determine which elements of LHS map to which elements of RHS. |
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</font><font color='#0000FF'>typedef</font> std::vector<font color='#5555FF'><</font><font color='#0000FF'><u>long</u></font><font color='#5555FF'>></font> label_type; |
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<font color='#009900'>// In this example, all our LHS and RHS elements will be 3-dimensional vectors. |
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</font><font color='#0000FF'>const</font> <font color='#0000FF'><u>unsigned</u></font> <font color='#0000FF'><u>long</u></font> num_dims <font color='#5555FF'>=</font> <font color='#979000'>3</font>; |
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<font color='#0000FF'><u>void</u></font> <b><a name='make_data'></a>make_data</b> <font face='Lucida Console'>(</font> |
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std::vector<font color='#5555FF'><</font>sample_type<font color='#5555FF'>></font><font color='#5555FF'>&</font> samples, |
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std::vector<font color='#5555FF'><</font>label_type<font color='#5555FF'>></font><font color='#5555FF'>&</font> labels |
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<font face='Lucida Console'>)</font>; |
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<font color='#009900'>/*! |
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ensures |
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- This function creates a training dataset of 5 example associations. |
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- #samples.size() == 5 |
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- #labels.size() == 5 |
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- for all valid i: |
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- #samples[i].first == a left hand set |
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- #samples[i].second == a right hand set |
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- #labels[i] == a set of integers indicating how to map LHS to RHS. To be |
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precise: |
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- #samples[i].first.size() == #labels[i].size() |
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- for all valid j: |
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-1 <= #labels[i][j] < #samples[i].second.size() |
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(A value of -1 indicates that #samples[i].first[j] isn't associated with anything. |
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All other values indicate the associating element of #samples[i].second) |
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- All elements of #labels[i] which are not equal to -1 are unique. That is, |
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multiple elements of #samples[i].first can't associate to the same element |
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in #samples[i].second. |
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!*/</font> |
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<font color='#009900'>// ---------------------------------------------------------------------------------------- |
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</font> |
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<font color='#0000FF'>struct</font> <b><a name='feature_extractor'></a>feature_extractor</b> |
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<b>{</b> |
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<font color='#009900'>/*! |
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Recall that our task is to learn the "goodness of assignment" function for |
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use with the Hungarian algorithm. The dlib tools assume this function |
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can be written as: |
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match_score(l,r) == dot(w, PSI(l,r)) + bias |
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where l is an element of LHS, r is an element of RHS, w is a parameter vector, |
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bias is a scalar value, and PSI() is a user supplied feature extractor. |
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This feature_extractor is where we implement PSI(). How you implement this |
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is highly problem dependent. |
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!*/</font> |
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<font color='#009900'>// The type of feature vector returned from get_features(). This must be either |
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</font> <font color='#009900'>// a dlib::matrix or a sparse vector. |
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</font> <font color='#0000FF'>typedef</font> column_vector feature_vector_type; |
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<font color='#009900'>// The types of elements in the LHS and RHS sets |
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</font> <font color='#0000FF'>typedef</font> column_vector lhs_element; |
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<font color='#0000FF'>typedef</font> column_vector rhs_element; |
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<font color='#0000FF'><u>unsigned</u></font> <font color='#0000FF'><u>long</u></font> <b><a name='num_features'></a>num_features</b><font face='Lucida Console'>(</font><font face='Lucida Console'>)</font> <font color='#0000FF'>const</font> |
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<b>{</b> |
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<font color='#009900'>// Return the dimensionality of feature vectors produced by get_features() |
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</font> <font color='#0000FF'>return</font> num_dims; |
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<b>}</b> |
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<font color='#0000FF'><u>void</u></font> <b><a name='get_features'></a>get_features</b> <font face='Lucida Console'>(</font> |
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<font color='#0000FF'>const</font> lhs_element<font color='#5555FF'>&</font> left, |
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<font color='#0000FF'>const</font> rhs_element<font color='#5555FF'>&</font> right, |
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feature_vector_type<font color='#5555FF'>&</font> feats |
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<font face='Lucida Console'>)</font> <font color='#0000FF'>const</font> |
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<font color='#009900'>/*! |
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ensures |
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- #feats == PSI(left,right) |
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(i.e. This function computes a feature vector which, in some sense, |
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captures information useful for deciding if matching left to right |
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is "good"). |
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!*/</font> |
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<b>{</b> |
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<font color='#009900'>// Let's just use the squared difference between each vector as our features. |
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</font> <font color='#009900'>// However, it should be emphasized that how to compute the features here is very |
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</font> <font color='#009900'>// problem dependent. |
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</font> feats <font color='#5555FF'>=</font> <font color='#BB00BB'>squared</font><font face='Lucida Console'>(</font>left <font color='#5555FF'>-</font> right<font face='Lucida Console'>)</font>; |
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<b>}</b> |
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<b>}</b>; |
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<font color='#009900'>// We need to define serialize() and deserialize() for our feature extractor if we want |
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</font><font color='#009900'>// to be able to serialize and deserialize our learned models. In this case the |
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</font><font color='#009900'>// implementation is empty since our feature_extractor doesn't have any state. But you |
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</font><font color='#009900'>// might define more complex feature extractors which have state that needs to be saved. |
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</font><font color='#0000FF'><u>void</u></font> <b><a name='serialize'></a>serialize</b> <font face='Lucida Console'>(</font><font color='#0000FF'>const</font> feature_extractor<font color='#5555FF'>&</font> , std::ostream<font color='#5555FF'>&</font> <font face='Lucida Console'>)</font> <b>{</b><b>}</b> |
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<font color='#0000FF'><u>void</u></font> <b><a name='deserialize'></a>deserialize</b> <font face='Lucida Console'>(</font>feature_extractor<font color='#5555FF'>&</font> , std::istream<font color='#5555FF'>&</font> <font face='Lucida Console'>)</font> <b>{</b><b>}</b> |
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<font color='#009900'>// ---------------------------------------------------------------------------------------- |
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</font> |
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<font color='#0000FF'><u>int</u></font> <b><a name='main'></a>main</b><font face='Lucida Console'>(</font><font face='Lucida Console'>)</font> |
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<b>{</b> |
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<font color='#0000FF'>try</font> |
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<b>{</b> |
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<font color='#009900'>// Get a small bit of training data. |
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</font> std::vector<font color='#5555FF'><</font>sample_type<font color='#5555FF'>></font> samples; |
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std::vector<font color='#5555FF'><</font>label_type<font color='#5555FF'>></font> labels; |
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<font color='#BB00BB'>make_data</font><font face='Lucida Console'>(</font>samples, labels<font face='Lucida Console'>)</font>; |
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structural_assignment_trainer<font color='#5555FF'><</font>feature_extractor<font color='#5555FF'>></font> trainer; |
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<font color='#009900'>// This is the common SVM C parameter. Larger values encourage the |
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</font> <font color='#009900'>// trainer to attempt to fit the data exactly but might overfit. |
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</font> <font color='#009900'>// In general, you determine this parameter by cross-validation. |
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</font> trainer.<font color='#BB00BB'>set_c</font><font face='Lucida Console'>(</font><font color='#979000'>10</font><font face='Lucida Console'>)</font>; |
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<font color='#009900'>// This trainer can use multiple CPU cores to speed up the training. |
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</font> <font color='#009900'>// So set this to the number of available CPU cores. |
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</font> trainer.<font color='#BB00BB'>set_num_threads</font><font face='Lucida Console'>(</font><font color='#979000'>4</font><font face='Lucida Console'>)</font>; |
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<font color='#009900'>// Do the training and save the results in assigner. |
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</font> assignment_function<font color='#5555FF'><</font>feature_extractor<font color='#5555FF'>></font> assigner <font color='#5555FF'>=</font> trainer.<font color='#BB00BB'>train</font><font face='Lucida Console'>(</font>samples, labels<font face='Lucida Console'>)</font>; |
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<font color='#009900'>// Test the assigner on our data. The output will indicate that it makes the |
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</font> <font color='#009900'>// correct associations on all samples. |
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</font> cout <font color='#5555FF'><</font><font color='#5555FF'><</font> "<font color='#CC0000'>Test the learned assignment function: </font>" <font color='#5555FF'><</font><font color='#5555FF'><</font> endl; |
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<font color='#0000FF'>for</font> <font face='Lucida Console'>(</font><font color='#0000FF'><u>unsigned</u></font> <font color='#0000FF'><u>long</u></font> i <font color='#5555FF'>=</font> <font color='#979000'>0</font>; i <font color='#5555FF'><</font> samples.<font color='#BB00BB'>size</font><font face='Lucida Console'>(</font><font face='Lucida Console'>)</font>; <font color='#5555FF'>+</font><font color='#5555FF'>+</font>i<font face='Lucida Console'>)</font> |
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<b>{</b> |
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<font color='#009900'>// Predict the assignments for the LHS and RHS in samples[i]. |
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</font> std::vector<font color='#5555FF'><</font><font color='#0000FF'><u>long</u></font><font color='#5555FF'>></font> predicted_assignments <font color='#5555FF'>=</font> <font color='#BB00BB'>assigner</font><font face='Lucida Console'>(</font>samples[i]<font face='Lucida Console'>)</font>; |
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cout <font color='#5555FF'><</font><font color='#5555FF'><</font> "<font color='#CC0000'>true labels: </font>" <font color='#5555FF'><</font><font color='#5555FF'><</font> <font color='#BB00BB'>trans</font><font face='Lucida Console'>(</font><font color='#BB00BB'>mat</font><font face='Lucida Console'>(</font>labels[i]<font face='Lucida Console'>)</font><font face='Lucida Console'>)</font>; |
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cout <font color='#5555FF'><</font><font color='#5555FF'><</font> "<font color='#CC0000'>predicted labels: </font>" <font color='#5555FF'><</font><font color='#5555FF'><</font> <font color='#BB00BB'>trans</font><font face='Lucida Console'>(</font><font color='#BB00BB'>mat</font><font face='Lucida Console'>(</font>predicted_assignments<font face='Lucida Console'>)</font><font face='Lucida Console'>)</font> <font color='#5555FF'><</font><font color='#5555FF'><</font> endl; |
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<b>}</b> |
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<font color='#009900'>// We can also use this tool to compute the percentage of assignments predicted correctly. |
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</font> cout <font color='#5555FF'><</font><font color='#5555FF'><</font> "<font color='#CC0000'>training accuracy: </font>" <font color='#5555FF'><</font><font color='#5555FF'><</font> <font color='#BB00BB'>test_assignment_function</font><font face='Lucida Console'>(</font>assigner, samples, labels<font face='Lucida Console'>)</font> <font color='#5555FF'><</font><font color='#5555FF'><</font> endl; |
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<font color='#009900'>// Since testing on your training data is a really bad idea, we can also do 5-fold cross validation. |
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</font> <font color='#009900'>// Happily, this also indicates that all associations were made correctly. |
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</font> <font color='#BB00BB'>randomize_samples</font><font face='Lucida Console'>(</font>samples, labels<font face='Lucida Console'>)</font>; |
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cout <font color='#5555FF'><</font><font color='#5555FF'><</font> "<font color='#CC0000'>cv accuracy: </font>" <font color='#5555FF'><</font><font color='#5555FF'><</font> <font color='#BB00BB'>cross_validate_assignment_trainer</font><font face='Lucida Console'>(</font>trainer, samples, labels, <font color='#979000'>5</font><font face='Lucida Console'>)</font> <font color='#5555FF'><</font><font color='#5555FF'><</font> endl; |
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<font color='#009900'>// Finally, the assigner can be serialized to disk just like most dlib objects. |
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</font> <font color='#BB00BB'>serialize</font><font face='Lucida Console'>(</font>"<font color='#CC0000'>assigner.dat</font>"<font face='Lucida Console'>)</font> <font color='#5555FF'><</font><font color='#5555FF'><</font> assigner; |
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<font color='#009900'>// recall from disk |
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</font> <font color='#BB00BB'>deserialize</font><font face='Lucida Console'>(</font>"<font color='#CC0000'>assigner.dat</font>"<font face='Lucida Console'>)</font> <font color='#5555FF'>></font><font color='#5555FF'>></font> assigner; |
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<b>}</b> |
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<font color='#0000FF'>catch</font> <font face='Lucida Console'>(</font>std::exception<font color='#5555FF'>&</font> e<font face='Lucida Console'>)</font> |
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<b>{</b> |
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cout <font color='#5555FF'><</font><font color='#5555FF'><</font> "<font color='#CC0000'>EXCEPTION THROWN</font>" <font color='#5555FF'><</font><font color='#5555FF'><</font> endl; |
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cout <font color='#5555FF'><</font><font color='#5555FF'><</font> e.<font color='#BB00BB'>what</font><font face='Lucida Console'>(</font><font face='Lucida Console'>)</font> <font color='#5555FF'><</font><font color='#5555FF'><</font> endl; |
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<b>}</b> |
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<b>}</b> |
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<font color='#009900'>// ---------------------------------------------------------------------------------------- |
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</font> |
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<font color='#0000FF'><u>void</u></font> <b><a name='make_data'></a>make_data</b> <font face='Lucida Console'>(</font> |
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std::vector<font color='#5555FF'><</font>sample_type<font color='#5555FF'>></font><font color='#5555FF'>&</font> samples, |
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std::vector<font color='#5555FF'><</font>label_type<font color='#5555FF'>></font><font color='#5555FF'>&</font> labels |
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<font face='Lucida Console'>)</font> |
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<b>{</b> |
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<font color='#009900'>// Make four different vectors. We will use them to make example assignments. |
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</font> column_vector <font color='#BB00BB'>A</font><font face='Lucida Console'>(</font>num_dims<font face='Lucida Console'>)</font>, <font color='#BB00BB'>B</font><font face='Lucida Console'>(</font>num_dims<font face='Lucida Console'>)</font>, <font color='#BB00BB'>C</font><font face='Lucida Console'>(</font>num_dims<font face='Lucida Console'>)</font>, <font color='#BB00BB'>D</font><font face='Lucida Console'>(</font>num_dims<font face='Lucida Console'>)</font>; |
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A <font color='#5555FF'>=</font> <font color='#979000'>1</font>,<font color='#979000'>0</font>,<font color='#979000'>0</font>; |
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B <font color='#5555FF'>=</font> <font color='#979000'>0</font>,<font color='#979000'>1</font>,<font color='#979000'>0</font>; |
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C <font color='#5555FF'>=</font> <font color='#979000'>0</font>,<font color='#979000'>0</font>,<font color='#979000'>1</font>; |
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D <font color='#5555FF'>=</font> <font color='#979000'>0</font>,<font color='#979000'>1</font>,<font color='#979000'>1</font>; |
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std::vector<font color='#5555FF'><</font>column_vector<font color='#5555FF'>></font> lhs; |
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std::vector<font color='#5555FF'><</font>column_vector<font color='#5555FF'>></font> rhs; |
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label_type mapping; |
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<font color='#009900'>// In all the assignments to follow, we will only say an element of the LHS |
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</font> <font color='#009900'>// matches an element of the RHS if the two are equal. So A matches with A, |
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</font> <font color='#009900'>// B with B, etc. But never A with C, for example. |
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</font> <font color='#009900'>// ------------------------ |
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</font> |
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lhs.<font color='#BB00BB'>resize</font><font face='Lucida Console'>(</font><font color='#979000'>3</font><font face='Lucida Console'>)</font>; |
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lhs[<font color='#979000'>0</font>] <font color='#5555FF'>=</font> A; |
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lhs[<font color='#979000'>1</font>] <font color='#5555FF'>=</font> B; |
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lhs[<font color='#979000'>2</font>] <font color='#5555FF'>=</font> C; |
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rhs.<font color='#BB00BB'>resize</font><font face='Lucida Console'>(</font><font color='#979000'>3</font><font face='Lucida Console'>)</font>; |
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rhs[<font color='#979000'>0</font>] <font color='#5555FF'>=</font> B; |
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rhs[<font color='#979000'>1</font>] <font color='#5555FF'>=</font> A; |
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rhs[<font color='#979000'>2</font>] <font color='#5555FF'>=</font> C; |
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mapping.<font color='#BB00BB'>resize</font><font face='Lucida Console'>(</font><font color='#979000'>3</font><font face='Lucida Console'>)</font>; |
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mapping[<font color='#979000'>0</font>] <font color='#5555FF'>=</font> <font color='#979000'>1</font>; <font color='#009900'>// lhs[0] matches rhs[1] |
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</font> mapping[<font color='#979000'>1</font>] <font color='#5555FF'>=</font> <font color='#979000'>0</font>; <font color='#009900'>// lhs[1] matches rhs[0] |
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</font> mapping[<font color='#979000'>2</font>] <font color='#5555FF'>=</font> <font color='#979000'>2</font>; <font color='#009900'>// lhs[2] matches rhs[2] |
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</font> |
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samples.<font color='#BB00BB'>push_back</font><font face='Lucida Console'>(</font><font color='#BB00BB'>make_pair</font><font face='Lucida Console'>(</font>lhs,rhs<font face='Lucida Console'>)</font><font face='Lucida Console'>)</font>; |
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labels.<font color='#BB00BB'>push_back</font><font face='Lucida Console'>(</font>mapping<font face='Lucida Console'>)</font>; |
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<font color='#009900'>// ------------------------ |
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</font> |
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lhs[<font color='#979000'>0</font>] <font color='#5555FF'>=</font> C; |
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lhs[<font color='#979000'>1</font>] <font color='#5555FF'>=</font> A; |
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lhs[<font color='#979000'>2</font>] <font color='#5555FF'>=</font> B; |
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rhs[<font color='#979000'>0</font>] <font color='#5555FF'>=</font> A; |
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rhs[<font color='#979000'>1</font>] <font color='#5555FF'>=</font> B; |
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rhs[<font color='#979000'>2</font>] <font color='#5555FF'>=</font> D; |
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mapping[<font color='#979000'>0</font>] <font color='#5555FF'>=</font> <font color='#5555FF'>-</font><font color='#979000'>1</font>; <font color='#009900'>// The -1 indicates that lhs[0] doesn't match anything in rhs. |
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</font> mapping[<font color='#979000'>1</font>] <font color='#5555FF'>=</font> <font color='#979000'>0</font>; <font color='#009900'>// lhs[1] matches rhs[0] |
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</font> mapping[<font color='#979000'>2</font>] <font color='#5555FF'>=</font> <font color='#979000'>1</font>; <font color='#009900'>// lhs[2] matches rhs[1] |
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</font> |
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samples.<font color='#BB00BB'>push_back</font><font face='Lucida Console'>(</font><font color='#BB00BB'>make_pair</font><font face='Lucida Console'>(</font>lhs,rhs<font face='Lucida Console'>)</font><font face='Lucida Console'>)</font>; |
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labels.<font color='#BB00BB'>push_back</font><font face='Lucida Console'>(</font>mapping<font face='Lucida Console'>)</font>; |
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<font color='#009900'>// ------------------------ |
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</font> |
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lhs[<font color='#979000'>0</font>] <font color='#5555FF'>=</font> A; |
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lhs[<font color='#979000'>1</font>] <font color='#5555FF'>=</font> B; |
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lhs[<font color='#979000'>2</font>] <font color='#5555FF'>=</font> C; |
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rhs.<font color='#BB00BB'>resize</font><font face='Lucida Console'>(</font><font color='#979000'>4</font><font face='Lucida Console'>)</font>; |
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rhs[<font color='#979000'>0</font>] <font color='#5555FF'>=</font> C; |
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rhs[<font color='#979000'>1</font>] <font color='#5555FF'>=</font> B; |
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rhs[<font color='#979000'>2</font>] <font color='#5555FF'>=</font> A; |
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rhs[<font color='#979000'>3</font>] <font color='#5555FF'>=</font> D; |
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mapping[<font color='#979000'>0</font>] <font color='#5555FF'>=</font> <font color='#979000'>2</font>; |
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mapping[<font color='#979000'>1</font>] <font color='#5555FF'>=</font> <font color='#979000'>1</font>; |
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mapping[<font color='#979000'>2</font>] <font color='#5555FF'>=</font> <font color='#979000'>0</font>; |
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samples.<font color='#BB00BB'>push_back</font><font face='Lucida Console'>(</font><font color='#BB00BB'>make_pair</font><font face='Lucida Console'>(</font>lhs,rhs<font face='Lucida Console'>)</font><font face='Lucida Console'>)</font>; |
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labels.<font color='#BB00BB'>push_back</font><font face='Lucida Console'>(</font>mapping<font face='Lucida Console'>)</font>; |
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<font color='#009900'>// ------------------------ |
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</font> |
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lhs.<font color='#BB00BB'>resize</font><font face='Lucida Console'>(</font><font color='#979000'>2</font><font face='Lucida Console'>)</font>; |
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lhs[<font color='#979000'>0</font>] <font color='#5555FF'>=</font> B; |
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lhs[<font color='#979000'>1</font>] <font color='#5555FF'>=</font> C; |
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rhs.<font color='#BB00BB'>resize</font><font face='Lucida Console'>(</font><font color='#979000'>3</font><font face='Lucida Console'>)</font>; |
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rhs[<font color='#979000'>0</font>] <font color='#5555FF'>=</font> C; |
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rhs[<font color='#979000'>1</font>] <font color='#5555FF'>=</font> A; |
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rhs[<font color='#979000'>2</font>] <font color='#5555FF'>=</font> D; |
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mapping.<font color='#BB00BB'>resize</font><font face='Lucida Console'>(</font><font color='#979000'>2</font><font face='Lucida Console'>)</font>; |
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mapping[<font color='#979000'>0</font>] <font color='#5555FF'>=</font> <font color='#5555FF'>-</font><font color='#979000'>1</font>; |
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mapping[<font color='#979000'>1</font>] <font color='#5555FF'>=</font> <font color='#979000'>0</font>; |
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samples.<font color='#BB00BB'>push_back</font><font face='Lucida Console'>(</font><font color='#BB00BB'>make_pair</font><font face='Lucida Console'>(</font>lhs,rhs<font face='Lucida Console'>)</font><font face='Lucida Console'>)</font>; |
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labels.<font color='#BB00BB'>push_back</font><font face='Lucida Console'>(</font>mapping<font face='Lucida Console'>)</font>; |
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<font color='#009900'>// ------------------------ |
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</font> |
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lhs.<font color='#BB00BB'>resize</font><font face='Lucida Console'>(</font><font color='#979000'>3</font><font face='Lucida Console'>)</font>; |
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lhs[<font color='#979000'>0</font>] <font color='#5555FF'>=</font> D; |
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lhs[<font color='#979000'>1</font>] <font color='#5555FF'>=</font> B; |
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lhs[<font color='#979000'>2</font>] <font color='#5555FF'>=</font> C; |
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<font color='#009900'>// rhs will be empty. So none of the items in lhs can match anything. |
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</font> rhs.<font color='#BB00BB'>resize</font><font face='Lucida Console'>(</font><font color='#979000'>0</font><font face='Lucida Console'>)</font>; |
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mapping.<font color='#BB00BB'>resize</font><font face='Lucida Console'>(</font><font color='#979000'>3</font><font face='Lucida Console'>)</font>; |
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mapping[<font color='#979000'>0</font>] <font color='#5555FF'>=</font> <font color='#5555FF'>-</font><font color='#979000'>1</font>; |
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mapping[<font color='#979000'>1</font>] <font color='#5555FF'>=</font> <font color='#5555FF'>-</font><font color='#979000'>1</font>; |
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mapping[<font color='#979000'>2</font>] <font color='#5555FF'>=</font> <font color='#5555FF'>-</font><font color='#979000'>1</font>; |
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|
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samples.<font color='#BB00BB'>push_back</font><font face='Lucida Console'>(</font><font color='#BB00BB'>make_pair</font><font face='Lucida Console'>(</font>lhs,rhs<font face='Lucida Console'>)</font><font face='Lucida Console'>)</font>; |
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labels.<font color='#BB00BB'>push_back</font><font face='Lucida Console'>(</font>mapping<font face='Lucida Console'>)</font>; |
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<b>}</b> |
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</pre></body></html> |
