Added exercises
This commit is contained in:
Nicolas Rougier
parent
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README.html
42
README.html
@ -34,7 +34,8 @@ is:</p>
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<p>Repository is at: <a class="reference external" href="https://github.com/rougier/numpy-100">https://github.com/rougier/numpy-100</a></p>
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<p>The corresponding <a class="reference external" href="https://github.com/rougier/numpy-100/blob/master/README.ipynb">IPython notebook</a> is available
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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>
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<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>
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<p>Thanks to Michiaki Ariga, there is now a
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<a class="reference external" href="https://github.com/chezou/julia-100-exercises">Julia version</a>.</p>
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<div class="section" id="neophyte">
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<h1>Neophyte</h1>
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<ol class="arabic">
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@ -257,16 +258,12 @@ point by point distances</p>
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<span class="keyword">print</span> <span class="name">G</span>
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</pre>
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</li>
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<li><p class="first">Consider the vector [1, 2, 3, 4, 5], how to build a new vector with 3
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consecutive zeros interleaved between each value ?</p>
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<li><p class="first">How to tell if a given 2D array has null columns ?</p>
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<pre class="code python literal-block">
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<span class="comment"># Author: Warren Weckesser</span>
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<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>
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<span class="name">nz</span> <span class="operator">=</span> <span class="literal number integer">3</span>
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<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>
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<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>
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<span class="keyword">print</span> <span class="name">Z0</span>
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<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>
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<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>
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</pre>
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</li>
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<li><p class="first">Find the nearest value from a given value in an array</p>
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@ -357,6 +354,35 @@ using a vector S of same size describing subset indices ?</p>
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<span class="keyword">print</span> <span class="name">D_means</span>
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</pre>
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</li>
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<li><p class="first">Consider the vector [1, 2, 3, 4, 5], how to build a new vector with 3
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consecutive zeros interleaved between each value ?</p>
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<pre class="code python literal-block">
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<span class="comment"># Author: Warren Weckesser</span>
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<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>
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<span class="name">nz</span> <span class="operator">=</span> <span class="literal number integer">3</span>
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<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>
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<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>
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<span class="keyword">print</span> <span class="name">Z0</span>
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</pre>
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</li>
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<li><p class="first">Consider an array of dimension (5,5,3), how to mulitply it by an array with
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dimensions (5,5) ?</p>
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<pre class="code python literal-block">
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<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>
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<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>
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<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>
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</pre>
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</li>
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<li><p class="first">How to swap two rows of an array ?</p>
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<pre class="code python literal-block">
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<span class="comment"># Author: Eelco Hoogendoorn</span>
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<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>
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<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>
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<span class="keyword">print</span> <span class="name">A</span>
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</pre>
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</li>
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</ol>
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</div>
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<div class="section" id="craftsman">
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75
README.ipynb
75
README.ipynb
@ -662,8 +662,7 @@
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"cell_type": "markdown",
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"metadata": {},
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"source": [
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"Consider the vector [1, 2, 3, 4, 5], how to build a new vector with 3\n",
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"consecutive zeros interleaved between each value ?\n"
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"How to tell if a given 2D array has null columns ?\n"
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]
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},
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{
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@ -672,11 +671,8 @@
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"input": [
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"# Author: Warren Weckesser\n",
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"\n",
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"Z = np.array([1,2,3,4,5])\n",
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"nz = 3\n",
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"Z0 = np.zeros(len(Z) + (len(Z)-1)*(nz))\n",
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"Z0[::nz+1] = Z\n",
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"print Z0"
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"Z = np.random.randint(0,3,(3,10))\n",
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"print (~Z.any(axis=0)).any()"
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],
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"language": "python",
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"metadata": {},
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@ -880,6 +876,71 @@
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"metadata": {},
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"outputs": []
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},
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{
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"cell_type": "markdown",
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"metadata": {},
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"source": [
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"Consider the vector [1, 2, 3, 4, 5], how to build a new vector with 3\n",
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"consecutive zeros interleaved between each value ?\n"
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]
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},
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{
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"cell_type": "code",
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"collapsed": false,
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"input": [
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"# Author: Warren Weckesser\n",
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"\n",
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"Z = np.array([1,2,3,4,5])\n",
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"nz = 3\n",
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"Z0 = np.zeros(len(Z) + (len(Z)-1)*(nz))\n",
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"Z0[::nz+1] = Z\n",
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"print Z0"
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],
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"language": "python",
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"metadata": {},
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"outputs": []
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},
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{
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"cell_type": "markdown",
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"metadata": {},
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"source": [
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"Consider an array of dimension (5,5,3), how to mulitply it by an array\n",
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"with dimensions (5,5) ?\n"
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]
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},
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{
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"cell_type": "code",
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"collapsed": false,
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"input": [
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"A = np.ones((5,5,3))\n",
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"B = 2*np.ones((5,5))\n",
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"print A * B[:,:,None]"
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],
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"language": "python",
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"metadata": {},
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"outputs": []
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},
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{
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"cell_type": "markdown",
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"metadata": {},
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"source": [
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"How to swap two rows of an array ?\n"
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]
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},
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{
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"cell_type": "code",
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"collapsed": false,
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"input": [
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"# Author: Eelco Hoogendoorn\n",
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"\n",
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"A = np.arange(25).reshape(5,5)\n",
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"A[[0,1]] = A[[1,0]]\n",
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"print A"
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],
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"language": "python",
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"metadata": {},
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"outputs": []
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},
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{
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"cell_type": "heading",
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"level": 2,
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50
README.rst
50
README.rst
@ -34,7 +34,8 @@ from the github repo, thanks to the `rst2ipynb
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<https://github.com/esc/rst2ipynb>`_ conversion tool by `Valentin Haenel
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<http://haenel.co>`_
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Thanks to Michiaki Ariga, there is now a `Julia version <https://github.com/chezou/julia-100-exercises>`_.
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Thanks to Michiaki Ariga, there is now a
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`Julia version <https://github.com/chezou/julia-100-exercises>`_.
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.. **Contents**
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@ -319,19 +320,14 @@ Apprentice
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print G
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9. Consider the vector [1, 2, 3, 4, 5], how to build a new vector with 3
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consecutive zeros interleaved between each value ?
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9. How to tell if a given 2D array has null columns ?
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.. code-block:: python
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# Author: Warren Weckesser
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Z = np.array([1,2,3,4,5])
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nz = 3
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Z0 = np.zeros(len(Z) + (len(Z)-1)*(nz))
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Z0[::nz+1] = Z
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print Z0
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Z = np.random.randint(0,3,(3,10))
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print (~Z.any(axis=0)).any()
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10. Find the nearest value from a given value in an array
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@ -410,6 +406,7 @@ Journeyman
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n = len(np.unique(F))
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print np.unique(I)
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6. Considering a four dimensions array, how to get sum over the last two axis at once ?
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.. code-block:: python
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@ -435,6 +432,41 @@ Journeyman
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print D_means
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8. Consider the vector [1, 2, 3, 4, 5], how to build a new vector with 3
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consecutive zeros interleaved between each value ?
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.. code-block:: python
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# Author: Warren Weckesser
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Z = np.array([1,2,3,4,5])
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nz = 3
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Z0 = np.zeros(len(Z) + (len(Z)-1)*(nz))
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Z0[::nz+1] = Z
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print Z0
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9. Consider an array of dimension (5,5,3), how to mulitply it by an array with
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dimensions (5,5) ?
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.. code-block:: python
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A = np.ones((5,5,3))
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B = 2*np.ones((5,5))
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print A * B[:,:,None]
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10. How to swap two rows of an array ?
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.. code-block:: python
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# Author: Eelco Hoogendoorn
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A = np.arange(25).reshape(5,5)
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A[[0,1]] = A[[1,0]]
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print A
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Craftsman
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=========
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