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python-cheatsheet
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CSV, SQLite

pull/57/head
Jure Šorn 4 years ago
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2 changed files with 14 additions and 14 deletions
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  1. 14
      README.md
  2. 14
      index.html

14
README.md
View File

@ -1775,7 +1775,7 @@ import csv
### Read
```python
<reader> = csv.reader(<file>, dialect='excel', delimiter=',')
<reader> = csv.reader(<file>) # Also: `dialect='excel', delimiter=','`.
<list> = next(<reader>) # Returns next row as a list of strings.
<list> = list(<reader>) # Returns list of remaining rows.
```
@ -1783,7 +1783,7 @@ import csv
### Write
```python
<writer> = csv.writer(<file>, dialect='excel', delimiter=',')
<writer> = csv.writer(<file>) # Also: `dialect='excel', delimiter=','`.
<writer>.writerow(<collection>) # Encodes objects using `str(<el>)`.
<writer>.writerows(<coll_of_coll>) # Appends multiple rows.
```
@ -1889,8 +1889,8 @@ db.executemany('<query>', <coll_of_above>) # Runs execute() many times.
```python
# $ pip3 install mysql-connector
from mysql import connector
db = connector.connect(host=<str>, user=<str>, password=<str>, database=<str>)
<cursor> = db.cursor()
db = connector.connect(host=<str>, …) # `user=<str>, password=<str>, database=<str>`.
<cursor> = db.cursor() # Only cursor has execute method.
<cursor>.execute('<query>') # Can raise a subclass of connector.Error.
<cursor>.execute('<query>', <list/tuple>) # Replaces '%s's in query with values.
<cursor>.execute('<query>', <dict/namedtuple>) # Replaces '%(<key>)s's with values.
@ -1912,7 +1912,7 @@ 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='big/little', signed=False`
<bytes> = <int>.to_bytes(n_bytes, …) # `byteorder='big/little', signed=False`.
<bytes> = bytes.fromhex('<hex>') # Hex numbers can be separated by spaces.
```
@ -1920,7 +1920,7 @@ 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='big/little', signed=False`
<int> = int.from_bytes(<bytes>, …) # `byteorder='big/little', signed=False`.
'<hex>' = <bytes>.hex() # Returns a string of hexadecimal numbers.
```
@ -2016,7 +2016,7 @@ Memory View
```python
<list> = list(<mview>) # Returns list of ints or floats.
<str> = str(<mview>, 'utf-8') # Treats mview as a bytes object.
<int> = int.from_bytes(<mview>, …) # `byteorder='big/little', signed=False`
<int> = int.from_bytes(<mview>, …) # `byteorder='big/little', signed=False`.
'<hex>' = <mview>.hex() # Treats mview as a bytes object.
```

14
index.html
View File

@ -1590,7 +1590,7 @@ CompletedProcess(args=[<span class="hljs-string">'bc'</span>, <span class="hljs-
</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>)
<div><h3 id="read">Read</h3><pre><code class="python language-python hljs">&lt;reader&gt; = csv.reader(&lt;file&gt;) <span class="hljs-comment"># Also: `dialect='excel', delimiter=','`.</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>
</code></pre></div>
@ -1598,7 +1598,7 @@ CompletedProcess(args=[<span class="hljs-string">'bc'</span>, <span class="hljs-
<ul>
<li><strong>File must be opened with <code class="python hljs"><span class="hljs-string">'newline=""'</span></code> argument, or newlines embedded inside quoted fields will not be interpreted correctly!</strong></li>
</ul>
<div><h3 id="write">Write</h3><pre><code class="python language-python hljs">&lt;writer&gt; = csv.writer(&lt;file&gt;, dialect=<span class="hljs-string">'excel'</span>, delimiter=<span class="hljs-string">','</span>)
<div><h3 id="write">Write</h3><pre><code class="python language-python hljs">&lt;writer&gt; = csv.writer(&lt;file&gt;) <span class="hljs-comment"># Also: `dialect='excel', delimiter=','`.</span>
&lt;writer&gt;.writerow(&lt;collection&gt;) <span class="hljs-comment"># Encodes objects using `str(&lt;el&gt;)`.</span>
&lt;writer&gt;.writerows(&lt;coll_of_coll&gt;) <span class="hljs-comment"># Appends multiple rows.</span>
</code></pre></div>
@ -1684,8 +1684,8 @@ db.executemany(<span class="hljs-string">'&lt;query&gt;'</span>, &lt;coll_of_abo
<div><h3 id="mysql">MySQL</h3><p><strong>Has a very similar interface, with differences listed below.</strong></p><pre><code class="python language-python hljs"><span class="hljs-comment"># $ pip3 install mysql-connector</span>
<span class="hljs-keyword">from</span> mysql <span class="hljs-keyword">import</span> connector
db = connector.connect(host=&lt;str&gt;, user=&lt;str&gt;, password=&lt;str&gt;, database=&lt;str&gt;)
&lt;cursor&gt; = db.cursor()
db = connector.connect(host=&lt;str&gt;, …) <span class="hljs-comment"># `user=&lt;str&gt;, password=&lt;str&gt;, database=&lt;str&gt;`.</span>
&lt;cursor&gt; = db.cursor() <span class="hljs-comment"># Only cursor has execute method.</span>
&lt;cursor&gt;.execute(<span class="hljs-string">'&lt;query&gt;'</span>) <span class="hljs-comment"># Can raise a subclass of connector.Error.</span>
&lt;cursor&gt;.execute(<span class="hljs-string">'&lt;query&gt;'</span>, &lt;list/tuple&gt;) <span class="hljs-comment"># Replaces '%s's in query with values.</span>
&lt;cursor&gt;.execute(<span class="hljs-string">'&lt;query&gt;'</span>, &lt;dict/namedtuple&gt;) <span class="hljs-comment"># Replaces '%(&lt;key&gt;)s's with values.</span>
@ -1701,13 +1701,13 @@ db = connector.connect(host=&lt;str&gt;, user=&lt;str&gt;, password=&lt;str&gt;,
<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='big/little', 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 numbers can be separated by spaces.</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='big/little', 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 a string of hexadecimal numbers.</span>
</code></pre></div>
@ -1786,7 +1786,7 @@ db = connector.connect(host=&lt;str&gt;, user=&lt;str&gt;, password=&lt;str&gt;,
<pre><code class="python language-python hljs">&lt;list&gt; = list(&lt;mview&gt;) <span class="hljs-comment"># Returns 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='big/little', 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

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