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python-cheatsheet
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Open, Array, Memory view, Plot

pull/102/merge
Jure Šorn 1 month ago
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2 changed files with 16 additions and 14 deletions
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  1. 13
      README.md
  2. 17
      index.html

13
README.md
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@ -1572,7 +1572,7 @@ Open
### Modes
* **`'r'` - Read (default).**
* **`'w'` - Write (truncate).**
* **`'w'` - Write (truncate, i.e. delete existing contents).**
* **`'x'` - Write or fail if the file already exists.**
* **`'a'` - Append.**
* **`'w+'` - Read and write (truncate).**
@ -2049,7 +2049,7 @@ from array import array
```python
<bytes> = bytes(<array>) # Returns a copy of array's memory.
<file>.write(<array>) # Writes array to the binary file.
<file>.write(<array>) # Writes array's memory to the file.
```
@ -2059,9 +2059,9 @@ Memory View
```python
<mview> = memoryview(<bytes/bytearray/array>) # Immutable if bytes, else mutable.
<real> = <mview>[index] # Returns an int or a float.
<obj> = <mview>[index] # Returns int, float or bytes ('c' format).
<mview> = <mview>[<slice>] # Returns mview with rearranged elements.
<mview> = <mview>.cast('<typecode>') # Only works between b/B/c and other types.
<mview> = <mview>.cast('<typecode>') # Only works between B/b/c and other types.
<mview>.release() # Releases memory buffer of the base object.
```
@ -2069,11 +2069,11 @@ Memory View
<bytes> = bytes(<mview>) # Returns a new bytes object.
<bytes> = <bytes>.join(<coll_of_mviews>) # Joins mviews using bytes as a separator.
<array> = array('<typecode>', <mview>) # Treats mview as a sequence of numbers.
<file>.write(<mview>) # Writes mview to the binary file.
<file>.write(<mview>) # Writes `bytes(<mview>)` to the file.
```
```python
<list> = list(<mview>) # Returns a list of ints or floats.
<list> = list(<mview>) # Returns a list of ints, floats or bytes.
<str> = str(<mview>, 'utf-8') # Treats mview as a bytes object.
<str> = <mview>.hex() # Returns hex pairs. Accepts `sep=<str>`.
```
@ -2413,6 +2413,7 @@ import matplotlib.pyplot as plt
plt.plot/bar/scatter(x_data, y_data [, label=<str>]) # Or: plt.plot(y_data)
plt.legend() # Adds a legend.
plt.title/xlabel/ylabel(<str>) # Adds a title/labels.
plt.savefig(<path>) # Saves the figure.
plt.show() # Displays the figure.
plt.clf() # Clears the figure.

17
index.html
View File

@ -54,7 +54,7 @@
<body>
<header>
<aside>August 22, 2024</aside>
<aside>August 24, 2024</aside>
<a href="https://gto76.github.io" rel="author">Jure Šorn</a>
</header>
@ -1334,7 +1334,7 @@ p.add_argument(<span class="hljs-string">'&lt;name&gt;'</span>, type=&lt;type&gt
</ul>
<div><h3 id="modes">Modes</h3><ul>
<li><strong><code class="python hljs"><span class="hljs-string">'r'</span></code> - Read (default).</strong></li>
<li><strong><code class="python hljs"><span class="hljs-string">'w'</span></code> - Write (truncate).</strong></li>
<li><strong><code class="python hljs"><span class="hljs-string">'w'</span></code> - Write (truncate, i.e. delete existing contents).</strong></li>
<li><strong><code class="python hljs"><span class="hljs-string">'x'</span></code> - Write or fail if the file already exists.</strong></li>
<li><strong><code class="python hljs"><span class="hljs-string">'a'</span></code> - Append.</strong></li>
<li><strong><code class="python hljs"><span class="hljs-string">'w+'</span></code> - Read and write (truncate).</strong></li>
@ -1695,12 +1695,12 @@ CompletedProcess(args=[<span class="hljs-string">'bc'</span>, <span class="hljs-
&lt;array&gt;.fromfile(&lt;file&gt;, n_items) <span class="hljs-comment"># Appends items from the binary file.</span>
</code></pre>
<pre><code class="python language-python hljs">&lt;bytes&gt; = bytes(&lt;array&gt;) <span class="hljs-comment"># Returns a copy of array's memory.</span>
&lt;file&gt;.write(&lt;array&gt;) <span class="hljs-comment"># Writes array to the binary file.</span>
&lt;file&gt;.write(&lt;array&gt;) <span class="hljs-comment"># Writes array's memory to the file.</span>
</code></pre>
<div><h2 id="memoryview"><a href="#memoryview" name="memoryview">#</a>Memory View</h2><p><strong>A sequence object that points to the memory of another bytes-like object. Each element can reference a single or multiple consecutive bytes, depending on format. Order and number of elements can be changed with slicing.</strong></p><pre><code class="python language-python hljs">&lt;mview&gt; = memoryview(&lt;bytes/bytearray/array&gt;) <span class="hljs-comment"># Immutable if bytes, else mutable.</span>
&lt;real&gt; = &lt;mview&gt;[index] <span class="hljs-comment"># Returns an int or a float.</span>
&lt;obj&gt; = &lt;mview&gt;[index] <span class="hljs-comment"># Returns int, float or bytes ('c' format).</span>
&lt;mview&gt; = &lt;mview&gt;[&lt;slice&gt;] <span class="hljs-comment"># Returns mview with rearranged elements.</span>
&lt;mview&gt; = &lt;mview&gt;.cast(<span class="hljs-string">'&lt;typecode&gt;'</span>) <span class="hljs-comment"># Only works between b/B/c and other types.</span>
&lt;mview&gt; = &lt;mview&gt;.cast(<span class="hljs-string">'&lt;typecode&gt;'</span>) <span class="hljs-comment"># Only works between B/b/c and other types.</span>
&lt;mview&gt;.release() <span class="hljs-comment"># Releases memory buffer of the base object.</span>
</code></pre></div>
@ -1708,9 +1708,9 @@ CompletedProcess(args=[<span class="hljs-string">'bc'</span>, <span class="hljs-
<pre><code class="python language-python hljs">&lt;bytes&gt; = bytes(&lt;mview&gt;) <span class="hljs-comment"># Returns a new bytes object.</span>
&lt;bytes&gt; = &lt;bytes&gt;.join(&lt;coll_of_mviews&gt;) <span class="hljs-comment"># Joins mviews using bytes as a separator.</span>
&lt;array&gt; = array(<span class="hljs-string">'&lt;typecode&gt;'</span>, &lt;mview&gt;) <span class="hljs-comment"># Treats mview as a sequence of numbers.</span>
&lt;file&gt;.write(&lt;mview&gt;) <span class="hljs-comment"># Writes mview to the binary file.</span>
&lt;file&gt;.write(&lt;mview&gt;) <span class="hljs-comment"># Writes `bytes(&lt;mview&gt;)` to the file.</span>
</code></pre>
<pre><code class="python language-python hljs">&lt;list&gt; = list(&lt;mview&gt;) <span class="hljs-comment"># Returns a list of ints or floats.</span>
<pre><code class="python language-python hljs">&lt;list&gt; = list(&lt;mview&gt;) <span class="hljs-comment"># Returns a list of ints, floats or bytes.</span>
&lt;str&gt; = str(&lt;mview&gt;, <span class="hljs-string">'utf-8'</span>) <span class="hljs-comment"># Treats mview as a bytes object.</span>
&lt;str&gt; = &lt;mview&gt;.hex() <span class="hljs-comment"># Returns hex pairs. Accepts `sep=&lt;str&gt;`.</span>
</code></pre>
@ -1980,6 +1980,7 @@ Processing: 100%|████████████████████| 3
plt.plot/bar/scatter(x_data, y_data [, label=&lt;str&gt;]) <span class="hljs-comment"># Or: plt.plot(y_data)</span>
plt.legend() <span class="hljs-comment"># Adds a legend.</span>
plt.title/xlabel/ylabel(&lt;str&gt;) <span class="hljs-comment"># Adds a title/labels.</span>
plt.savefig(&lt;path&gt;) <span class="hljs-comment"># Saves the figure.</span>
plt.show() <span class="hljs-comment"># Displays the figure.</span>
plt.clf() <span class="hljs-comment"># Clears the figure.</span>
@ -2932,7 +2933,7 @@ $ deactivate <span class="hljs-comment"># Deactivates the activ
<footer>
<aside>August 22, 2024</aside>
<aside>August 24, 2024</aside>
<a href="https://gto76.github.io" rel="author">Jure Šorn</a>
</footer>

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