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python-cheatsheet
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Jure Šorn 2 years ago
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  1. 13
      README.md
  2. 15
      index.html

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README.md
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@ -381,6 +381,7 @@ import re
* **By default, decimal characters, alphanumerics and whitespaces from all alphabets are matched unless `'flags=re.ASCII'` argument is used.** * **By default, decimal characters, alphanumerics and whitespaces from all alphabets are matched unless `'flags=re.ASCII'` argument is used.**
* **As shown below, it restricts special sequence matches to the first 128 characters and prevents `'\s'` from accepting `'[\x1c-\x1f]'` (the so-called separator characters).** * **As shown below, it restricts special sequence matches to the first 128 characters and prevents `'\s'` from accepting `'[\x1c-\x1f]'` (the so-called separator characters).**
* **Use a capital letter for negation.** * **Use a capital letter for negation.**
```python ```python
'\d' == '[0-9]' # Matches decimal characters. '\d' == '[0-9]' # Matches decimal characters.
'\w' == '[a-zA-Z0-9_]' # Matches alphanumerics and underscore. '\w' == '[a-zA-Z0-9_]' # Matches alphanumerics and underscore.
@ -1548,7 +1549,7 @@ Open
``` ```
* **`'encoding=None'` means that the default encoding is used, which is platform dependent. Best practice is to use `'encoding="utf-8"'` whenever possible.** * **`'encoding=None'` means that the default encoding is used, which is platform dependent. Best practice is to use `'encoding="utf-8"'` whenever possible.**
* **`'newline=None'` means all different end of line combinations are converted to '\n' on read, while on write all '\n' characters are converted to system's default line separator.** * **`'newline=None'` means all different end of line combinations are converted to '\n' on read, while on write all '\n' characters are converted to system's default line separator.**
* **`'newline=""'` means no conversions take place, but input is still broken into chunks by readline() and readlines() on '\n', '\r' and '\r\n'.**
* **`'newline=""'` means no conversions take place, but input is still broken into chunks by readline() and readlines() on every '\n', '\r' and '\r\n'.**
### Modes ### Modes
* **`'r'` - Read (default).** * **`'r'` - Read (default).**
@ -1898,8 +1899,7 @@ with <conn>: # Exits the block with commit()
``` ```
### Example ### Example
**In this example values are not actually saved because `'conn.commit()'` is omitted!**
**Values are not actually saved in this example because `'conn.commit()'` is omitted!**
```python ```python
>>> conn = sqlite3.connect('test.db') >>> conn = sqlite3.connect('test.db')
>>> conn.execute('CREATE TABLE person (person_id INTEGER PRIMARY KEY, name, height)') >>> conn.execute('CREATE TABLE person (person_id INTEGER PRIMARY KEY, name, height)')
@ -3147,7 +3147,6 @@ Name: a, dtype: int64
<Sr> = <Sr>.rank/diff/cumsum/ffill/interpl() # Or: <Sr>.agg/transform(lambda <Sr>: <Sr>) <Sr> = <Sr>.rank/diff/cumsum/ffill/interpl() # Or: <Sr>.agg/transform(lambda <Sr>: <Sr>)
<Sr> = <Sr>.fillna(<el>) # Or: <Sr>.agg/transform/map(lambda <el>: <el>) <Sr> = <Sr>.fillna(<el>) # Or: <Sr>.agg/transform/map(lambda <el>: <el>)
``` ```
* **The way `'agg()'` and `'transform()'` find out whether the passed function accepts an element or the whole Series is by passing it a single value at first and if it raises an error, then they pass it the whole Series. `'agg()'` only accepts Attribute/Type/ValueError.**
```python ```python
>>> sr = Series([1, 2], index=['x', 'y']) >>> sr = Series([1, 2], index=['x', 'y'])
@ -3173,6 +3172,12 @@ y 2
``` ```
* **Last result has a hierarchical index. Use `'<Sr>[key_1, key_2]'` to get its values.** * **Last result has a hierarchical index. Use `'<Sr>[key_1, key_2]'` to get its values.**
#### Series — Plot:
```python
import matplotlib.pyplot as plt
<Sr>.plot.line/area/bar/pie/hist(); plt.show()
```
### DataFrame ### DataFrame
**Table with labeled rows and columns.** **Table with labeled rows and columns.**

15
index.html
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@ -54,7 +54,7 @@
<body> <body>
<header> <header>
<aside>March 3, 2022</aside>
<aside>March 8, 2022</aside>
<a href="https://gto76.github.io" rel="author">Jure Šorn</a> <a href="https://gto76.github.io" rel="author">Jure Šorn</a>
</header> </header>
@ -1319,7 +1319,7 @@ value = args.&lt;name&gt;
<ul> <ul>
<li><strong><code class="python hljs"><span class="hljs-string">'encoding=None'</span></code> means that the default encoding is used, which is platform dependent. Best practice is to use <code class="python hljs"><span class="hljs-string">'encoding="utf-8"'</span></code> whenever possible.</strong></li> <li><strong><code class="python hljs"><span class="hljs-string">'encoding=None'</span></code> means that the default encoding is used, which is platform dependent. Best practice is to use <code class="python hljs"><span class="hljs-string">'encoding="utf-8"'</span></code> whenever possible.</strong></li>
<li><strong><code class="python hljs"><span class="hljs-string">'newline=None'</span></code> means all different end of line combinations are converted to '\n' on read, while on write all '\n' characters are converted to system's default line separator.</strong></li> <li><strong><code class="python hljs"><span class="hljs-string">'newline=None'</span></code> means all different end of line combinations are converted to '\n' on read, while on write all '\n' characters are converted to system's default line separator.</strong></li>
<li><strong><code class="python hljs"><span class="hljs-string">'newline=""'</span></code> means no conversions take place, but input is still broken into chunks by readline() and readlines() on '\n', '\r' and '\r\n'.</strong></li>
<li><strong><code class="python hljs"><span class="hljs-string">'newline=""'</span></code> means no conversions take place, but input is still broken into chunks by readline() and readlines() on every '\n', '\r' and '\r\n'.</strong></li>
</ul> </ul>
<div><h3 id="modes">Modes</h3><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">'r'</span></code> - Read (default).</strong></li>
@ -1577,7 +1577,7 @@ CompletedProcess(args=[<span class="hljs-string">'bc'</span>, <span class="hljs-
</code></pre></div> </code></pre></div>
<div><h3 id="example">Example</h3><p><strong>In this example values are not actually saved because <code class="python hljs"><span class="hljs-string">'conn.commit()'</span></code> is omitted!</strong></p><pre><code class="python language-python hljs"><span class="hljs-meta">&gt;&gt;&gt; </span>conn = sqlite3.connect(<span class="hljs-string">'test.db'</span>)
<div><h3 id="example">Example</h3><p><strong>Values are not actually saved in this example because <code class="python hljs"><span class="hljs-string">'conn.commit()'</span></code> is omitted!</strong></p><pre><code class="python language-python hljs"><span class="hljs-meta">&gt;&gt;&gt; </span>conn = sqlite3.connect(<span class="hljs-string">'test.db'</span>)
<span class="hljs-meta">&gt;&gt;&gt; </span>conn.execute(<span class="hljs-string">'CREATE TABLE person (person_id INTEGER PRIMARY KEY, name, height)'</span>) <span class="hljs-meta">&gt;&gt;&gt; </span>conn.execute(<span class="hljs-string">'CREATE TABLE person (person_id INTEGER PRIMARY KEY, name, height)'</span>)
<span class="hljs-meta">&gt;&gt;&gt; </span>conn.execute(<span class="hljs-string">'INSERT INTO person VALUES (NULL, ?, ?)'</span>, (<span class="hljs-string">'Jean-Luc'</span>, <span class="hljs-number">187</span>)).lastrowid <span class="hljs-meta">&gt;&gt;&gt; </span>conn.execute(<span class="hljs-string">'INSERT INTO person VALUES (NULL, ?, ?)'</span>, (<span class="hljs-string">'Jean-Luc'</span>, <span class="hljs-number">187</span>)).lastrowid
<span class="hljs-number">1</span> <span class="hljs-number">1</span>
@ -2555,9 +2555,6 @@ Name: a, dtype: int64
&lt;Sr&gt; = &lt;Sr&gt;.fillna(&lt;el&gt;) <span class="hljs-comment"># Or: &lt;Sr&gt;.agg/transform/map(lambda &lt;el&gt;: &lt;el&gt;)</span> &lt;Sr&gt; = &lt;Sr&gt;.fillna(&lt;el&gt;) <span class="hljs-comment"># Or: &lt;Sr&gt;.agg/transform/map(lambda &lt;el&gt;: &lt;el&gt;)</span>
</code></pre></div> </code></pre></div>
<ul>
<li><strong>The way <code class="python hljs"><span class="hljs-string">'agg()'</span></code> and <code class="python hljs"><span class="hljs-string">'transform()'</span></code> find out whether the passed function accepts an element or the whole Series is by passing it a single value at first and if it raises an error, then they pass it the whole Series. <code class="python hljs"><span class="hljs-string">'agg()'</span></code> only accepts Attribute/Type/ValueError.</strong></li>
</ul>
<pre><code class="python language-python hljs"><span class="hljs-meta">&gt;&gt;&gt; </span>sr = Series([<span class="hljs-number">1</span>, <span class="hljs-number">2</span>], index=[<span class="hljs-string">'x'</span>, <span class="hljs-string">'y'</span>]) <pre><code class="python language-python hljs"><span class="hljs-meta">&gt;&gt;&gt; </span>sr = Series([<span class="hljs-number">1</span>, <span class="hljs-number">2</span>], index=[<span class="hljs-string">'x'</span>, <span class="hljs-string">'y'</span>])
x <span class="hljs-number">1</span> x <span class="hljs-number">1</span>
y <span class="hljs-number">2</span> y <span class="hljs-number">2</span>
@ -2580,6 +2577,10 @@ y <span class="hljs-number">2</span>
<ul> <ul>
<li><strong>Last result has a hierarchical index. Use <code class="python hljs"><span class="hljs-string">'&lt;Sr&gt;[key_1, key_2]'</span></code> to get its values.</strong></li> <li><strong>Last result has a hierarchical index. Use <code class="python hljs"><span class="hljs-string">'&lt;Sr&gt;[key_1, key_2]'</span></code> to get its values.</strong></li>
</ul> </ul>
<div><h4 id="seriesplot">Series — Plot:</h4><pre><code class="python language-python hljs"><span class="hljs-keyword">import</span> matplotlib.pyplot <span class="hljs-keyword">as</span> plt
&lt;Sr&gt;.plot.line/area/bar/pie/hist(); plt.show()
</code></pre></div>
<div><h3 id="dataframe">DataFrame</h3><p><strong>Table with labeled rows and columns.</strong></p><pre><code class="python language-python hljs"><span class="hljs-meta">&gt;&gt;&gt; </span>DataFrame([[<span class="hljs-number">1</span>, <span class="hljs-number">2</span>], [<span class="hljs-number">3</span>, <span class="hljs-number">4</span>]], index=[<span class="hljs-string">'a'</span>, <span class="hljs-string">'b'</span>], columns=[<span class="hljs-string">'x'</span>, <span class="hljs-string">'y'</span>]) <div><h3 id="dataframe">DataFrame</h3><p><strong>Table with labeled rows and columns.</strong></p><pre><code class="python language-python hljs"><span class="hljs-meta">&gt;&gt;&gt; </span>DataFrame([[<span class="hljs-number">1</span>, <span class="hljs-number">2</span>], [<span class="hljs-number">3</span>, <span class="hljs-number">4</span>]], index=[<span class="hljs-string">'a'</span>, <span class="hljs-string">'b'</span>], columns=[<span class="hljs-string">'x'</span>, <span class="hljs-string">'y'</span>])
x y x y
a <span class="hljs-number">1</span> <span class="hljs-number">2</span> a <span class="hljs-number">1</span> <span class="hljs-number">2</span>
@ -2884,7 +2885,7 @@ $ pyinstaller script.py --add-data '&lt;path&gt;:.' <span class="hljs-comment">
<footer> <footer>
<aside>March 3, 2022</aside>
<aside>March 8, 2022</aside>
<a href="https://gto76.github.io" rel="author">Jure Šorn</a> <a href="https://gto76.github.io" rel="author">Jure Šorn</a>
</footer> </footer>

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