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Nicolas Rougier
2014-06-23 09:32:51 +02:00
parent 3a04802449
commit 8647fc74fd
3 changed files with 143 additions and 24 deletions
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@@ -34,7 +34,8 @@ is:</p>
<p>Repository is at: <a class="reference external" href="https://github.com/rougier/numpy-100">https://github.com/rougier/numpy-100</a></p>
<p>The corresponding <a class="reference external" href="https://github.com/rougier/numpy-100/blob/master/README.ipynb">IPython notebook</a> is available
from the github repo, thanks to the <a class="reference external" href="https://github.com/esc/rst2ipynb">rst2ipynb</a> conversion tool by <a class="reference external" href="http://haenel.co">Valentin Haenel</a></p>
<p>Thanks to Michiaki Ariga, there is now a <a class="reference external" href="https://github.com/chezou/julia-100-exercises">Julia version</a>.</p>
<p>Thanks to Michiaki Ariga, there is now a
<a class="reference external" href="https://github.com/chezou/julia-100-exercises">Julia version</a>.</p>
<div class="section" id="neophyte">
<h1>Neophyte</h1>
<ol class="arabic">
@@ -257,16 +258,12 @@ point by point distances</p>
<span class="keyword">print</span> <span class="name">G</span>
</pre>
</li>
<li><p class="first">Consider the vector [1, 2, 3, 4, 5], how to build a new vector with 3
consecutive zeros interleaved between each value ?</p>
<li><p class="first">How to tell if a given 2D array has null columns ?</p>
<pre class="code python literal-block">
<span class="comment"># Author: Warren Weckesser</span>
<span class="name">Z</span> <span class="operator">=</span> <span class="name">np</span><span class="operator">.</span><span class="name">array</span><span class="punctuation">([</span><span class="literal number integer">1</span><span class="punctuation">,</span><span class="literal number integer">2</span><span class="punctuation">,</span><span class="literal number integer">3</span><span class="punctuation">,</span><span class="literal number integer">4</span><span class="punctuation">,</span><span class="literal number integer">5</span><span class="punctuation">])</span>
<span class="name">nz</span> <span class="operator">=</span> <span class="literal number integer">3</span>
<span class="name">Z0</span> <span class="operator">=</span> <span class="name">np</span><span class="operator">.</span><span class="name">zeros</span><span class="punctuation">(</span><span class="name builtin">len</span><span class="punctuation">(</span><span class="name">Z</span><span class="punctuation">)</span> <span class="operator">+</span> <span class="punctuation">(</span><span class="name builtin">len</span><span class="punctuation">(</span><span class="name">Z</span><span class="punctuation">)</span><span class="operator">-</span><span class="literal number integer">1</span><span class="punctuation">)</span><span class="operator">*</span><span class="punctuation">(</span><span class="name">nz</span><span class="punctuation">))</span>
<span class="name">Z0</span><span class="punctuation">[::</span><span class="name">nz</span><span class="operator">+</span><span class="literal number integer">1</span><span class="punctuation">]</span> <span class="operator">=</span> <span class="name">Z</span>
<span class="keyword">print</span> <span class="name">Z0</span>
<span class="name">Z</span> <span class="operator">=</span> <span class="name">np</span><span class="operator">.</span><span class="name">random</span><span class="operator">.</span><span class="name">randint</span><span class="punctuation">(</span><span class="literal number integer">0</span><span class="punctuation">,</span><span class="literal number integer">3</span><span class="punctuation">,(</span><span class="literal number integer">3</span><span class="punctuation">,</span><span class="literal number integer">10</span><span class="punctuation">))</span>
<span class="keyword">print</span> <span class="punctuation">(</span><span class="operator">~</span><span class="name">Z</span><span class="operator">.</span><span class="name">any</span><span class="punctuation">(</span><span class="name">axis</span><span class="operator">=</span><span class="literal number integer">0</span><span class="punctuation">))</span><span class="operator">.</span><span class="name">any</span><span class="punctuation">()</span>
</pre>
</li>
<li><p class="first">Find the nearest value from a given value in an array</p>
@@ -357,6 +354,35 @@ using a vector S of same size describing subset indices ?</p>
<span class="keyword">print</span> <span class="name">D_means</span>
</pre>
</li>
<li><p class="first">Consider the vector [1, 2, 3, 4, 5], how to build a new vector with 3
consecutive zeros interleaved between each value ?</p>
<pre class="code python literal-block">
<span class="comment"># Author: Warren Weckesser</span>
<span class="name">Z</span> <span class="operator">=</span> <span class="name">np</span><span class="operator">.</span><span class="name">array</span><span class="punctuation">([</span><span class="literal number integer">1</span><span class="punctuation">,</span><span class="literal number integer">2</span><span class="punctuation">,</span><span class="literal number integer">3</span><span class="punctuation">,</span><span class="literal number integer">4</span><span class="punctuation">,</span><span class="literal number integer">5</span><span class="punctuation">])</span>
<span class="name">nz</span> <span class="operator">=</span> <span class="literal number integer">3</span>
<span class="name">Z0</span> <span class="operator">=</span> <span class="name">np</span><span class="operator">.</span><span class="name">zeros</span><span class="punctuation">(</span><span class="name builtin">len</span><span class="punctuation">(</span><span class="name">Z</span><span class="punctuation">)</span> <span class="operator">+</span> <span class="punctuation">(</span><span class="name builtin">len</span><span class="punctuation">(</span><span class="name">Z</span><span class="punctuation">)</span><span class="operator">-</span><span class="literal number integer">1</span><span class="punctuation">)</span><span class="operator">*</span><span class="punctuation">(</span><span class="name">nz</span><span class="punctuation">))</span>
<span class="name">Z0</span><span class="punctuation">[::</span><span class="name">nz</span><span class="operator">+</span><span class="literal number integer">1</span><span class="punctuation">]</span> <span class="operator">=</span> <span class="name">Z</span>
<span class="keyword">print</span> <span class="name">Z0</span>
</pre>
</li>
<li><p class="first">Consider an array of dimension (5,5,3), how to mulitply it by an array with
dimensions (5,5) ?</p>
<pre class="code python literal-block">
<span class="name">A</span> <span class="operator">=</span> <span class="name">np</span><span class="operator">.</span><span class="name">ones</span><span class="punctuation">((</span><span class="literal number integer">5</span><span class="punctuation">,</span><span class="literal number integer">5</span><span class="punctuation">,</span><span class="literal number integer">3</span><span class="punctuation">))</span>
<span class="name">B</span> <span class="operator">=</span> <span class="literal number integer">2</span><span class="operator">*</span><span class="name">np</span><span class="operator">.</span><span class="name">ones</span><span class="punctuation">((</span><span class="literal number integer">5</span><span class="punctuation">,</span><span class="literal number integer">5</span><span class="punctuation">))</span>
<span class="keyword">print</span> <span class="name">A</span> <span class="operator">*</span> <span class="name">B</span><span class="punctuation">[:,:,</span><span class="name builtin pseudo">None</span><span class="punctuation">]</span>
</pre>
</li>
<li><p class="first">How to swap two rows of an array ?</p>
<pre class="code python literal-block">
<span class="comment"># Author: Eelco Hoogendoorn</span>
<span class="name">A</span> <span class="operator">=</span> <span class="name">np</span><span class="operator">.</span><span class="name">arange</span><span class="punctuation">(</span><span class="literal number integer">25</span><span class="punctuation">)</span><span class="operator">.</span><span class="name">reshape</span><span class="punctuation">(</span><span class="literal number integer">5</span><span class="punctuation">,</span><span class="literal number integer">5</span><span class="punctuation">)</span>
<span class="name">A</span><span class="punctuation">[[</span><span class="literal number integer">0</span><span class="punctuation">,</span><span class="literal number integer">1</span><span class="punctuation">]]</span> <span class="operator">=</span> <span class="name">A</span><span class="punctuation">[[</span><span class="literal number integer">1</span><span class="punctuation">,</span><span class="literal number integer">0</span><span class="punctuation">]]</span>
<span class="keyword">print</span> <span class="name">A</span>
</pre>
</li>
</ol>
</div>
<div class="section" id="craftsman">