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python-cheatsheet
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Bytes, NumPy, Pandas

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Jure Šorn 1 year ago
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2 changed files with 12 additions and 12 deletions
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  1. 10
      README.md
  2. 14
      index.html

10
README.md
View File

@ -1956,7 +1956,7 @@ Bytes
```python
<bytes> = bytes(<coll_of_ints>) # Ints must be in range from 0 to 255.
<bytes> = bytes(<str>, 'utf-8') # Or: <str>.encode('utf-8')
<bytes> = <int>.to_bytes(n_bytes, …) # `byteorder='little/big', signed=False`.
<bytes> = <int>.to_bytes(n_bytes, …) # `byteorder='big/little', signed=False`.
<bytes> = bytes.fromhex('<hex>') # Hex pairs can be separated by whitespaces.
```
@ -1964,7 +1964,7 @@ Bytes
```python
<list> = list(<bytes>) # Returns ints in range from 0 to 255.
<str> = str(<bytes>, 'utf-8') # Or: <bytes>.decode('utf-8')
<int> = int.from_bytes(<bytes>, …) # `byteorder='little/big', signed=False`.
<int> = int.from_bytes(<bytes>, …) # `byteorder='big/little', signed=False`.
'<hex>' = <bytes>.hex() # Returns hex pairs. Accepts `sep=<str>`.
```
@ -2064,7 +2064,7 @@ Memory View
```python
<list> = list(<mview>) # Returns a list of ints or floats.
<str> = str(<mview>, 'utf-8') # Treats mview as a bytes object.
<int> = int.from_bytes(<mview>, …) # `byteorder='little/big', signed=False`.
<int> = int.from_bytes(<mview>, …) # `byteorder='big/little', signed=False`.
'<hex>' = <mview>.hex() # Treats mview as a bytes object.
```
@ -2658,7 +2658,7 @@ import numpy as np
* **Shape is a tuple of dimension sizes. A 100x50 RGB image has shape (50, 100, 3).**
* **Axis is an index of the dimension that gets aggregated. Leftmost dimension has index 0. Summing the RGB image along axis 2 will return a greyscale image with shape (50, 100).**
* **Passing a tuple of axes will chain the operations like this: `'<array>.<method>(axis_1, keepdims=True).<method>(axis_2).squeeze()'`.**
* **Passing a tuple of axes will chain the operations like this: `'<array>.<method>(axis_1).<method>(axis_2 - 1 if axis_2 > axis_1 else axis_2)'`.**
### Indexing
```bash
@ -3236,7 +3236,7 @@ b 3 4
```python
<DF> = <DF>.set_index(column_key) # Replaces row keys with values from a column.
<DF> = <DF>.reset_index(drop=False) # Moves row keys to a column named index.
<DF> = <DF>.reset_index(drop=False) # Drops or moves row keys to column named index.
<DF> = <DF>.sort_index(ascending=True) # Sorts rows by row keys. Use `axis=1` for cols.
<DF> = <DF>.sort_values(column_key/s) # Sorts rows by the passed column/s. Same.
```

14
index.html
View File

@ -54,7 +54,7 @@
<body>
<header>
<aside>December 31, 2022</aside>
<aside>January 16, 2023</aside>
<a href="https://gto76.github.io" rel="author">Jure Šorn</a>
</header>
@ -1624,13 +1624,13 @@ CompletedProcess(args=[<span class="hljs-string">'bc'</span>, <span class="hljs-
<div><h3 id="encode-1">Encode</h3><pre><code class="python language-python hljs">&lt;bytes&gt; = bytes(&lt;coll_of_ints&gt;) <span class="hljs-comment"># Ints must be in range from 0 to 255.</span>
&lt;bytes&gt; = bytes(&lt;str&gt;, <span class="hljs-string">'utf-8'</span>) <span class="hljs-comment"># Or: &lt;str&gt;.encode('utf-8')</span>
&lt;bytes&gt; = &lt;int&gt;.to_bytes(n_bytes, …) <span class="hljs-comment"># `byteorder='little/big', signed=False`.</span>
&lt;bytes&gt; = &lt;int&gt;.to_bytes(n_bytes, …) <span class="hljs-comment"># `byteorder='big/little', signed=False`.</span>
&lt;bytes&gt; = bytes.fromhex(<span class="hljs-string">'&lt;hex&gt;'</span>) <span class="hljs-comment"># Hex pairs can be separated by whitespaces.</span>
</code></pre></div>
<div><h3 id="decode-1">Decode</h3><pre><code class="python language-python hljs">&lt;list&gt; = list(&lt;bytes&gt;) <span class="hljs-comment"># Returns ints in range from 0 to 255.</span>
&lt;str&gt; = str(&lt;bytes&gt;, <span class="hljs-string">'utf-8'</span>) <span class="hljs-comment"># Or: &lt;bytes&gt;.decode('utf-8')</span>
&lt;int&gt; = int.from_bytes(&lt;bytes&gt;, …) <span class="hljs-comment"># `byteorder='little/big', signed=False`.</span>
&lt;int&gt; = int.from_bytes(&lt;bytes&gt;, …) <span class="hljs-comment"># `byteorder='big/little', signed=False`.</span>
<span class="hljs-string">'&lt;hex&gt;'</span> = &lt;bytes&gt;.hex() <span class="hljs-comment"># Returns hex pairs. Accepts `sep=&lt;str&gt;`.</span>
</code></pre></div>
@ -1714,7 +1714,7 @@ CompletedProcess(args=[<span class="hljs-string">'bc'</span>, <span class="hljs-
<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>
&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;int&gt; = int.from_bytes(&lt;mview&gt;, …) <span class="hljs-comment"># `byteorder='little/big', signed=False`.</span>
&lt;int&gt; = int.from_bytes(&lt;mview&gt;, …) <span class="hljs-comment"># `byteorder='big/little', signed=False`.</span>
<span class="hljs-string">'&lt;hex&gt;'</span> = &lt;mview&gt;.hex() <span class="hljs-comment"># Treats mview as a bytes object.</span>
</code></pre>
<div><h2 id="deque"><a href="#deque" name="deque">#</a>Deque</h2><p><strong>A thread-safe list with efficient appends and pops from either side. Pronounced "deck".</strong></p><pre><code class="python language-python hljs"><span class="hljs-keyword">from</span> collections <span class="hljs-keyword">import</span> deque
@ -2176,7 +2176,7 @@ drawer = cg.output.GraphvizOutput(output_file=filename)
<ul>
<li><strong>Shape is a tuple of dimension sizes. A 100x50 RGB image has shape (50, 100, 3).</strong></li>
<li><strong>Axis is an index of the dimension that gets aggregated. Leftmost dimension has index 0. Summing the RGB image along axis 2 will return a greyscale image with shape (50, 100).</strong></li>
<li><strong>Passing a tuple of axes will chain the operations like this: <code class="python hljs"><span class="hljs-string">'&lt;array&gt;.&lt;method&gt;(axis_1, keepdims=True).&lt;method&gt;(axis_2).squeeze()'</span></code>.</strong></li>
<li><strong>Passing a tuple of axes will chain the operations like this: <code class="python hljs"><span class="hljs-string">'&lt;array&gt;.&lt;method&gt;(axis_1).&lt;method&gt;(axis_2 - 1 if axis_2 &gt; axis_1 else axis_2)'</span></code>.</strong></li>
</ul>
<div><h3 id="indexing">Indexing</h3><pre><code class="bash language-bash hljs">&lt;el&gt; = &lt;2d_array&gt;[row_index, column_index] <span class="hljs-comment"># &lt;3d_a&gt;[table_i, row_i, column_i]</span>
&lt;1d_view&gt; = &lt;2d_array&gt;[row_index] <span class="hljs-comment"># &lt;3d_a&gt;[table_i, row_i]</span>
@ -2637,7 +2637,7 @@ b <span class="hljs-number">3</span> <span class="hljs-number">4</span>
&lt;DF&gt; = &lt;DF&gt; +-*/ &lt;el/Sr/DF&gt; <span class="hljs-comment"># Items with non-matching keys get value NaN.</span>
</code></pre>
<pre><code class="python language-python hljs">&lt;DF&gt; = &lt;DF&gt;.set_index(column_key) <span class="hljs-comment"># Replaces row keys with values from a column.</span>
&lt;DF&gt; = &lt;DF&gt;.reset_index(drop=<span class="hljs-keyword">False</span>) <span class="hljs-comment"># Moves row keys to a column named index.</span>
&lt;DF&gt; = &lt;DF&gt;.reset_index(drop=<span class="hljs-keyword">False</span>) <span class="hljs-comment"># Drops or moves row keys to column named index.</span>
&lt;DF&gt; = &lt;DF&gt;.sort_index(ascending=<span class="hljs-keyword">True</span>) <span class="hljs-comment"># Sorts rows by row keys. Use `axis=1` for cols.</span>
&lt;DF&gt; = &lt;DF&gt;.sort_values(column_key/s) <span class="hljs-comment"># Sorts rows by the passed column/s. Same.</span>
</code></pre>
@ -2920,7 +2920,7 @@ $ pyinstaller script.py --add-data '&lt;path&gt;:.' <span class="hljs-comment">
<footer>
<aside>December 31, 2022</aside>
<aside>January 16, 2023</aside>
<a href="https://gto76.github.io" rel="author">Jure Šorn</a>
</footer>

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