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<h1>Source code for torchreid.metrics.distance</h1><div class="highlight"><pre>
<span></span><span class="kn">from</span> <span class="nn">__future__</span> <span class="k">import</span> <span class="n">absolute_import</span>
<span class="kn">from</span> <span class="nn">__future__</span> <span class="k">import</span> <span class="n">print_function</span>
<span class="kn">from</span> <span class="nn">__future__</span> <span class="k">import</span> <span class="n">division</span>
<span class="kn">import</span> <span class="nn">numpy</span> <span class="k">as</span> <span class="nn">np</span>
<span class="kn">import</span> <span class="nn">torch</span>
<span class="kn">from</span> <span class="nn">torch.nn</span> <span class="k">import</span> <span class="n">functional</span> <span class="k">as</span> <span class="n">F</span>
<div class="viewcode-block" id="compute_distance_matrix"><a class="viewcode-back" href="../../../pkg/metrics.html#torchreid.metrics.distance.compute_distance_matrix">[docs]</a><span class="k">def</span> <span class="nf">compute_distance_matrix</span><span class="p">(</span><span class="n">input1</span><span class="p">,</span> <span class="n">input2</span><span class="p">,</span> <span class="n">metric</span><span class="o">=</span><span class="s1">&#39;euclidean&#39;</span><span class="p">):</span>
<span class="sd">&quot;&quot;&quot;A wrapper function for computing distance matrix.</span>
<span class="sd"> Args:</span>
<span class="sd"> input1 (torch.Tensor): 2-D feature matrix.</span>
<span class="sd"> input2 (torch.Tensor): 2-D feature matrix.</span>
<span class="sd"> metric (str, optional): &quot;euclidean&quot; or &quot;cosine&quot;.</span>
<span class="sd"> Default is &quot;euclidean&quot;.</span>
<span class="sd"> Returns:</span>
<span class="sd"> torch.Tensor: distance matrix.</span>
<span class="sd"> Examples::</span>
<span class="sd"> &gt;&gt;&gt; from torchreid import metrics</span>
<span class="sd"> &gt;&gt;&gt; input1 = torch.rand(10, 2048)</span>
<span class="sd"> &gt;&gt;&gt; input2 = torch.rand(100, 2048)</span>
<span class="sd"> &gt;&gt;&gt; distmat = metrics.compute_distance_matrix(input1, input2)</span>
<span class="sd"> &gt;&gt;&gt; distmat.size() # (10, 100)</span>
<span class="sd"> &quot;&quot;&quot;</span>
<span class="c1"># check input</span>
<span class="k">assert</span> <span class="nb">isinstance</span><span class="p">(</span><span class="n">input1</span><span class="p">,</span> <span class="n">torch</span><span class="o">.</span><span class="n">Tensor</span><span class="p">)</span>
<span class="k">assert</span> <span class="nb">isinstance</span><span class="p">(</span><span class="n">input2</span><span class="p">,</span> <span class="n">torch</span><span class="o">.</span><span class="n">Tensor</span><span class="p">)</span>
<span class="k">assert</span> <span class="n">input1</span><span class="o">.</span><span class="n">dim</span><span class="p">()</span> <span class="o">==</span> <span class="mi">2</span><span class="p">,</span> <span class="s1">&#39;Expected 2-D tensor, but got </span><span class="si">{}</span><span class="s1">-D&#39;</span><span class="o">.</span><span class="n">format</span><span class="p">(</span><span class="n">input1</span><span class="o">.</span><span class="n">dim</span><span class="p">())</span>
<span class="k">assert</span> <span class="n">input2</span><span class="o">.</span><span class="n">dim</span><span class="p">()</span> <span class="o">==</span> <span class="mi">2</span><span class="p">,</span> <span class="s1">&#39;Expected 2-D tensor, but got </span><span class="si">{}</span><span class="s1">-D&#39;</span><span class="o">.</span><span class="n">format</span><span class="p">(</span><span class="n">input2</span><span class="o">.</span><span class="n">dim</span><span class="p">())</span>
<span class="k">assert</span> <span class="n">input1</span><span class="o">.</span><span class="n">size</span><span class="p">(</span><span class="mi">1</span><span class="p">)</span> <span class="o">==</span> <span class="n">input2</span><span class="o">.</span><span class="n">size</span><span class="p">(</span><span class="mi">1</span><span class="p">)</span>
<span class="k">if</span> <span class="n">metric</span> <span class="o">==</span> <span class="s1">&#39;euclidean&#39;</span><span class="p">:</span>
<span class="n">distmat</span> <span class="o">=</span> <span class="n">euclidean_squared_distance</span><span class="p">(</span><span class="n">input1</span><span class="p">,</span> <span class="n">input2</span><span class="p">)</span>
<span class="k">elif</span> <span class="n">metric</span> <span class="o">==</span> <span class="s1">&#39;cosine&#39;</span><span class="p">:</span>
<span class="n">distmat</span> <span class="o">=</span> <span class="n">cosine_distance</span><span class="p">(</span><span class="n">input1</span><span class="p">,</span> <span class="n">input2</span><span class="p">)</span>
<span class="k">else</span><span class="p">:</span>
<span class="k">raise</span> <span class="ne">ValueError</span><span class="p">(</span>
<span class="s1">&#39;Unknown distance metric: </span><span class="si">{}</span><span class="s1">. &#39;</span>
<span class="s1">&#39;Please choose either &quot;euclidean&quot; or &quot;cosine&quot;&#39;</span><span class="o">.</span><span class="n">format</span><span class="p">(</span><span class="n">metric</span><span class="p">)</span>
<span class="p">)</span>
<span class="k">return</span> <span class="n">distmat</span></div>
<div class="viewcode-block" id="euclidean_squared_distance"><a class="viewcode-back" href="../../../pkg/metrics.html#torchreid.metrics.distance.euclidean_squared_distance">[docs]</a><span class="k">def</span> <span class="nf">euclidean_squared_distance</span><span class="p">(</span><span class="n">input1</span><span class="p">,</span> <span class="n">input2</span><span class="p">):</span>
<span class="sd">&quot;&quot;&quot;Computes euclidean squared distance.</span>
<span class="sd"> Args:</span>
<span class="sd"> input1 (torch.Tensor): 2-D feature matrix.</span>
<span class="sd"> input2 (torch.Tensor): 2-D feature matrix.</span>
<span class="sd"> Returns:</span>
<span class="sd"> torch.Tensor: distance matrix.</span>
<span class="sd"> &quot;&quot;&quot;</span>
<span class="n">m</span><span class="p">,</span> <span class="n">n</span> <span class="o">=</span> <span class="n">input1</span><span class="o">.</span><span class="n">size</span><span class="p">(</span><span class="mi">0</span><span class="p">),</span> <span class="n">input2</span><span class="o">.</span><span class="n">size</span><span class="p">(</span><span class="mi">0</span><span class="p">)</span>
<span class="n">distmat</span> <span class="o">=</span> <span class="n">torch</span><span class="o">.</span><span class="n">pow</span><span class="p">(</span><span class="n">input1</span><span class="p">,</span> <span class="mi">2</span><span class="p">)</span><span class="o">.</span><span class="n">sum</span><span class="p">(</span><span class="n">dim</span><span class="o">=</span><span class="mi">1</span><span class="p">,</span> <span class="n">keepdim</span><span class="o">=</span><span class="kc">True</span><span class="p">)</span><span class="o">.</span><span class="n">expand</span><span class="p">(</span><span class="n">m</span><span class="p">,</span> <span class="n">n</span><span class="p">)</span> <span class="o">+</span> \
<span class="n">torch</span><span class="o">.</span><span class="n">pow</span><span class="p">(</span><span class="n">input2</span><span class="p">,</span> <span class="mi">2</span><span class="p">)</span><span class="o">.</span><span class="n">sum</span><span class="p">(</span><span class="n">dim</span><span class="o">=</span><span class="mi">1</span><span class="p">,</span> <span class="n">keepdim</span><span class="o">=</span><span class="kc">True</span><span class="p">)</span><span class="o">.</span><span class="n">expand</span><span class="p">(</span><span class="n">n</span><span class="p">,</span> <span class="n">m</span><span class="p">)</span><span class="o">.</span><span class="n">t</span><span class="p">()</span>
<span class="n">distmat</span><span class="o">.</span><span class="n">addmm_</span><span class="p">(</span><span class="mi">1</span><span class="p">,</span> <span class="o">-</span><span class="mi">2</span><span class="p">,</span> <span class="n">input1</span><span class="p">,</span> <span class="n">input2</span><span class="o">.</span><span class="n">t</span><span class="p">())</span>
<span class="k">return</span> <span class="n">distmat</span></div>
<div class="viewcode-block" id="cosine_distance"><a class="viewcode-back" href="../../../pkg/metrics.html#torchreid.metrics.distance.cosine_distance">[docs]</a><span class="k">def</span> <span class="nf">cosine_distance</span><span class="p">(</span><span class="n">input1</span><span class="p">,</span> <span class="n">input2</span><span class="p">):</span>
<span class="sd">&quot;&quot;&quot;Computes cosine distance.</span>
<span class="sd"> Args:</span>
<span class="sd"> input1 (torch.Tensor): 2-D feature matrix.</span>
<span class="sd"> input2 (torch.Tensor): 2-D feature matrix.</span>
<span class="sd"> Returns:</span>
<span class="sd"> torch.Tensor: distance matrix.</span>
<span class="sd"> &quot;&quot;&quot;</span>
<span class="n">input1_normed</span> <span class="o">=</span> <span class="n">F</span><span class="o">.</span><span class="n">normalize</span><span class="p">(</span><span class="n">input1</span><span class="p">,</span> <span class="n">p</span><span class="o">=</span><span class="mi">2</span><span class="p">,</span> <span class="n">dim</span><span class="o">=</span><span class="mi">1</span><span class="p">)</span>
<span class="n">input2_normed</span> <span class="o">=</span> <span class="n">F</span><span class="o">.</span><span class="n">normalize</span><span class="p">(</span><span class="n">input2</span><span class="p">,</span> <span class="n">p</span><span class="o">=</span><span class="mi">2</span><span class="p">,</span> <span class="n">dim</span><span class="o">=</span><span class="mi">1</span><span class="p">)</span>
<span class="n">distmat</span> <span class="o">=</span> <span class="mi">1</span> <span class="o">-</span> <span class="n">torch</span><span class="o">.</span><span class="n">mm</span><span class="p">(</span><span class="n">input1_normed</span><span class="p">,</span> <span class="n">input2_normed</span><span class="o">.</span><span class="n">t</span><span class="p">())</span>
<span class="k">return</span> <span class="n">distmat</span></div>
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