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python-cheatsheet
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Memory view

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Jure Šorn 5 years ago
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  1. 19
      README.md
  2. 18
      index.html
  3. 2
      parse.js

19
README.md
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@ -11,7 +11,7 @@ Contents
**   ** **1. Collections:** ** ** **[`List`](#list)**__,__ **[`Dictionary`](#dictionary)**__,__ **[`Set`](#set)**__,__ **[`Tuple`](#tuple)**__,__ **[`Range`](#range)**__,__ **[`Enumerate`](#enumerate)**__,__ **[`Iterator`](#iterator)**__,__ **[`Generator`](#generator)**__.__
**   ** **2. Types:** **          ** **[`Type`](#type)**__,__ **[`String`](#string)**__,__ **[`Regular_Exp`](#regex)**__,__ **[`Format`](#format)**__,__ **[`Numbers`](#numbers)**__,__ **[`Combinatorics`](#combinatorics)**__,__ **[`Datetime`](#datetime)**__.__
**   ** **3. Syntax:** **         ** **[`Args`](#arguments)**__,__ **[`Inline`](#inline)**__,__ **[`Closure`](#closure)**__,__ **[`Decorator`](#decorator)**__,__ **[`Class`](#class)**__,__ **[`Duck_Types`](#duck-types)**__,__ **[`Enum`](#enum)**__,__ **[`Exceptions`](#exceptions)**__.__
**   ** **4. System:** **        ** **[`Print`](#print)**__,__ **[`Input`](#input)**__,__ **[`Command_Line_Arguments`](#command-line-arguments)**__,__ **[`Open`](#open)**__,__ **[`Path`](#path)**__,__ **[`Command_Execution`](#command-execution)**__.__
**   ** **4. System:** **        ** **[`Print`](#print)**__,__ **[`Input`](#input)**__,__ **[`Command_Line_Arguments`](#command-line-arguments)**__,__ **[`Open`](#open)**__,__ **[`Path`](#path)**__,__ **[`Command_Execution`](#oscommands)**__.__
**   ** **5. Data:** **             ** **[`CSV`](#csv)**__,__ **[`SQLite`](#sqlite)**__,__ **[`JSON`](#json)**__,__ **[`Pickle`](#pickle)**__,__ **[`Bytes`](#bytes)**__,__ **[`Struct`](#struct)**__,__ **[`Array`](#array)**__,__ **[`MemoryView`](#memory-view)**__,__ **[`Deque`](#deque)**__.__
**   ** **6. Advanced:** **   ** **[`Threading`](#threading)**__,__ **[`Operator`](#operator)**__,__ **[`Introspection`](#introspection)**__,__ **[`Metaprograming`](#metaprograming)**__,__ **[`Eval`](#eval)**__,__ **[`Coroutine`](#coroutine)**__.__
**   ** **7. Libraries:** **      ** **[`Progress_Bar`](#progress-bar)**__,__ **[`Plot`](#plot)**__,__ **[`Table`](#table)**__,__ **[`Curses`](#curses)**__,__ **[`Logging`](#logging)**__,__ **[`Scraping`](#scraping)**__,__ **[`Web`](#web)**__,__ **[`Profile`](#profiling)**__,__
@ -1613,8 +1613,8 @@ cwd = Path()
```
Command Execution
-----------------
OS Commands
-----------
### Files and Directories
* **Paths can be either strings, Paths, or DirEntry objects.**
* **Functions report OS related errors by raising either OSError or one of its [subclasses](#exceptions-1).**
@ -1684,6 +1684,8 @@ b'.\n..\nfile1.txt\nfile2.txt\n'
CSV
---
**Text file format for storing spreadsheets.**
```python
import csv
```
@ -1949,16 +1951,16 @@ from array import array
Memory View
-----------
* **Memory View is a seqence that points to the memory of bytes, bytearray or array objects.**
* **Each element can reference a single or multiple consecutive bytes.**
* **Referenced elements can be narrowed down with slicing.**
* **A seqence object that points to the memory of another object.**
* **Each element can reference a single or multiple consecutive bytes, depending on format.**
* **Order and number of elements can be changed with slicing.**
```python
<mview> = memoryview(<bytes/bytearray/array>)
<num> = <mview>[<index>] # Can be int or float.
<mview> = <mview>[<slice>] # Mview with rearanged elements.
<mview> = <mview>.cast('<typecode>') # Cast a memoryview to a new format.
<mview>.release() # Releases the buffer.
<mview> = <mview>.cast('<typecode>') # Casts a memoryview to a new format.
<mview>.release() # Releases the object's memory buffer.
```
```python
@ -2237,6 +2239,7 @@ def printer():
reader(adder(printer())) # 100, 101, ..., 109
```
<br>
Libraries

18
index.html
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@ -213,7 +213,7 @@ pre.prettyprint {
<strong><span class="hljs-string"><span class="hljs-string">'1. Collections'</span></span></strong>: [<a href="#list">List</a>, <a href="#dictionary">Dictionary</a>, <a href="#set">Set</a>, <a href="#tuple">Tuple</a>, <a href="#range">Range</a>, <a href="#enumerate">Enumerate</a>, <a href="#iterator">Iterator</a>, <a href="#generator">Generator</a>],
<strong><span class="hljs-string"><span class="hljs-string">'2. Types'</span></span></strong>: [<a href="#type">Type</a>, <a href="#string">String</a>, <a href="#regex">Regular_Exp</a>, <a href="#format">Format</a>, <a href="#numbers">Numbers</a>, <a href="#combinatorics">Combinatorics</a>, <a href="#datetime">Datetime</a>],
<strong><span class="hljs-string"><span class="hljs-string">'3. Syntax'</span></span></strong>: [<a href="#arguments">Args</a>, <a href="#inline">Inline</a>, <a href="#closure">Closure</a>, <a href="#decorator">Decorator</a>, <a href="#class">Class</a>, <a href="#ducktypes">Duck_Types</a>, <a href="#enum">Enum</a>, <a href="#exceptions">Exceptions</a>],
<strong><span class="hljs-string"><span class="hljs-string">'4. System'</span></span></strong>: [<a href="#print">Print</a>, <a href="#input">Input</a>, <a href="#commandlinearguments">Command_Line_Arguments</a>, <a href="#open">Open</a>, <a href="#path">Path</a>, <a href="#commandexecution">Command_Execution</a>],
<strong><span class="hljs-string"><span class="hljs-string">'4. System'</span></span></strong>: [<a href="#print">Print</a>, <a href="#input">Input</a>, <a href="#commandlinearguments">Command_Line_Arguments</a>, <a href="#open">Open</a>, <a href="#path">Path</a>, <a href="#oscommands">Command_Execution</a>],
<strong><span class="hljs-string"><span class="hljs-string">'5. Data'</span></span></strong>: [<a href="#csv">CSV</a>, <a href="#sqlite">SQLite</a>, <a href="#json">JSON</a>, <a href="#pickle">Pickle</a>, <a href="#bytes">Bytes</a>, <a href="#struct">Struct</a>, <a href="#array">Array</a>, <a href="#memoryview">MemoryView</a>, <a href="#deque">Deque</a>],
<strong><span class="hljs-string"><span class="hljs-string">'6. Advanced'</span></span></strong>: [<a href="#threading">Threading</a>, <a href="#operator">Operator</a>, <a href="#introspection">Introspection</a>, <a href="#metaprograming">Metaprograming</a>, <a href="#eval">Eval</a>, <a href="#coroutine">Coroutine</a>],
<strong><span class="hljs-string"><span class="hljs-string">'7. Libraries'</span></span></strong>: [<a href="#progressbar">Progress_Bar</a>, <a href="#plot">Plot</a>, <a href="#table">Table</a>, <a href="#curses">Curses</a>, <a href="#logging">Logging</a>, <a href="#scraping">Scraping</a>, <a href="#web">Web</a>, <a href="#profiling">Profile</a>,
@ -1469,7 +1469,7 @@ value = args.&lt;name&gt;
&lt;Path&gt; = &lt;Path&gt;.parent <span class="hljs-comment"># Returns path without final component.</span>
&lt;file&gt; = open(&lt;Path&gt;) <span class="hljs-comment"># Opens the file and returns a file object.</span>
</code></pre>
<div><h2 id="commandexecution"><a href="#commandexecution" name="commandexecution">#</a>Command Execution</h2><div><h3 id="filesanddirectories">Files and Directories</h3><ul>
<div><h2 id="oscommands"><a href="#oscommands" name="oscommands">#</a>OS Commands</h2><div><h3 id="filesanddirectories">Files and Directories</h3><ul>
<li><strong>Paths can be either strings, Paths, or DirEntry objects.</strong></li>
<li><strong>Functions report OS related errors by raising either OSError or one of its <a href="#exceptions-1">subclasses</a>.</strong></li>
</ul><pre><code class="python language-python hljs"><span class="hljs-keyword">import</span> os, shutil
@ -1515,9 +1515,10 @@ shutil.copytree(from, to) <span class="hljs-comment"># Copies the entir
<span class="hljs-number">0</span>
</code></pre></div>
<div><h2 id="csv"><a href="#csv" name="csv">#</a>CSV</h2><pre><code class="python language-python hljs"><span class="hljs-keyword">import</span> csv
<div><h2 id="csv"><a href="#csv" name="csv">#</a>CSV</h2><p><strong>Text file format for storing spreadsheets.</strong></p><pre><code class="python language-python hljs"><span class="hljs-keyword">import</span> csv
</code></pre></div>
<div><h3 id="read">Read</h3><pre><code class="python language-python hljs">&lt;reader&gt; = csv.reader(&lt;file&gt;, dialect=<span class="hljs-string">'excel'</span>, delimiter=<span class="hljs-string">','</span>)
&lt;list&gt; = next(&lt;reader&gt;) <span class="hljs-comment"># Returns next row as a list of strings.</span>
&lt;list&gt; = list(&lt;reader&gt;) <span class="hljs-comment"># Returns list of remaining rows.</span>
@ -1728,14 +1729,14 @@ db = connector.connect(host=&lt;str&gt;, user=&lt;str&gt;, password=&lt;str&gt;,
<div><h2 id="memoryview"><a href="#memoryview" name="memoryview">#</a>Memory View</h2><ul>
<li><strong>Memory View is a seqence that points to the memory of bytes, bytearray or array objects.</strong></li>
<li><strong>Each element can reference a single or multiple consecutive bytes.</strong></li>
<li><strong>Referenced elements can be narrowed down with slicing.</strong></li>
<li><strong>A seqence object that points to the memory of another object.</strong></li>
<li><strong>Each element can reference a single or multiple consecutive bytes, depending on format.</strong></li>
<li><strong>Order and number of elements can be changed with slicing.</strong></li>
</ul><pre><code class="python language-python hljs">&lt;mview&gt; = memoryview(&lt;bytes/bytearray/array&gt;)
&lt;num&gt; = &lt;mview&gt;[&lt;index&gt;] <span class="hljs-comment"># Can be int or float.</span>
&lt;mview&gt; = &lt;mview&gt;[&lt;slice&gt;] <span class="hljs-comment"># Mview with rearanged elements.</span>
&lt;mview&gt; = &lt;mview&gt;.cast(<span class="hljs-string">'&lt;typecode&gt;'</span>) <span class="hljs-comment"># Cast a memoryview to a new format.</span>
&lt;mview&gt;.release() <span class="hljs-comment"># Releases the buffer.</span>
&lt;mview&gt; = &lt;mview&gt;.cast(<span class="hljs-string">'&lt;typecode&gt;'</span>) <span class="hljs-comment"># Casts a memoryview to a new format.</span>
&lt;mview&gt;.release() <span class="hljs-comment"># Releases the object's memory buffer.</span>
</code></pre></div>
@ -1943,6 +1944,7 @@ ValueError: malformed node or string
reader(adder(printer())) <span class="hljs-comment"># 100, 101, ..., 109</span>
</code></pre></div>
<p><br></p>
<div><h1 id="libraries">Libraries</h1><div><h2 id="progressbar"><a href="#progressbar" name="progressbar">#</a>Progress Bar</h2><pre><code class="python language-python hljs"><span class="hljs-comment"># $ pip3 install tqdm</span>
<span class="hljs-keyword">from</span> tqdm <span class="hljs-keyword">import</span> tqdm
<span class="hljs-keyword">from</span> time <span class="hljs-keyword">import</span> sleep

2
parse.js
View File

@ -22,7 +22,7 @@ const TOC =
' <strong><span class="hljs-string">\'1. Collections\'</span></strong>: [<a href="#list">List</a>, <a href="#dictionary">Dictionary</a>, <a href="#set">Set</a>, <a href="#tuple">Tuple</a>, <a href="#range">Range</a>, <a href="#enumerate">Enumerate</a>, <a href="#iterator">Iterator</a>, <a href="#generator">Generator</a>],\n' +
' <strong><span class="hljs-string">\'2. Types\'</span></strong>: [<a href="#type">Type</a>, <a href="#string">String</a>, <a href="#regex">Regular_Exp</a>, <a href="#format">Format</a>, <a href="#numbers">Numbers</a>, <a href="#combinatorics">Combinatorics</a>, <a href="#datetime">Datetime</a>],\n' +
' <strong><span class="hljs-string">\'3. Syntax\'</span></strong>: [<a href="#arguments">Args</a>, <a href="#inline">Inline</a>, <a href="#closure">Closure</a>, <a href="#decorator">Decorator</a>, <a href="#class">Class</a>, <a href="#ducktypes">Duck_Types</a>, <a href="#enum">Enum</a>, <a href="#exceptions">Exceptions</a>],\n' +
' <strong><span class="hljs-string">\'4. System\'</span></strong>: [<a href="#print">Print</a>, <a href="#input">Input</a>, <a href="#commandlinearguments">Command_Line_Arguments</a>, <a href="#open">Open</a>, <a href="#path">Path</a>, <a href="#commandexecution">Command_Execution</a>],\n' +
' <strong><span class="hljs-string">\'4. System\'</span></strong>: [<a href="#print">Print</a>, <a href="#input">Input</a>, <a href="#commandlinearguments">Command_Line_Arguments</a>, <a href="#open">Open</a>, <a href="#path">Path</a>, <a href="#oscommands">Command_Execution</a>],\n' +
' <strong><span class="hljs-string">\'5. Data\'</span></strong>: [<a href="#csv">CSV</a>, <a href="#sqlite">SQLite</a>, <a href="#json">JSON</a>, <a href="#pickle">Pickle</a>, <a href="#bytes">Bytes</a>, <a href="#struct">Struct</a>, <a href="#array">Array</a>, <a href="#memoryview">MemoryView</a>, <a href="#deque">Deque</a>],\n' +
' <strong><span class="hljs-string">\'6. Advanced\'</span></strong>: [<a href="#threading">Threading</a>, <a href="#operator">Operator</a>, <a href="#introspection">Introspection</a>, <a href="#metaprograming">Metaprograming</a>, <a href="#eval">Eval</a>, <a href="#coroutine">Coroutine</a>],\n' +
' <strong><span class="hljs-string">\'7. Libraries\'</span></strong>: [<a href="#progressbar">Progress_Bar</a>, <a href="#plot">Plot</a>, <a href="#table">Table</a>, <a href="#curses">Curses</a>, <a href="#logging">Logging</a>, <a href="#scraping">Scraping</a>, <a href="#web">Web</a>, <a href="#profiling">Profile</a>,\n' +

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