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python-cheatsheet
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Jure Šorn 5 years ago
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  1. 39
      README.md
  2. 38
      index.html

39
README.md
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@ -1640,13 +1640,46 @@ CSV
---
```python
import csv
<reader> = csv.reader(<file>, dialect='excel', delimiter=',', ...)
<list> = next(<reader>) # Returns a row as list of strings.
```
```python
<writer> = csv.writer(<file>, dialect='excel', delimiter=',', ...)
<writer>.writerow(<collection>)
<writer>.writerows(<coll_of_coll>)
```
### Parameters
* **`'dialect'` - Master parameter that sets the default values.**
* **`'delimiter'` - A one-character string used to separate fields.**
* **`'quotechar'` - Character for quoting fields that contain special characters.**
* **`'doublequote'` - Whether quotechars inside fields get doubled or escaped.**
* **`'skipinitialspace'` - Whether whitespace after delimiter gets stripped.**
* **`'lineterminator'` - How does writer terminate lines.**
* **`'quoting'` - Controls the amount of quoting: 0 - as necessary, 1 - all.**
* **`'escapechar'` - Character for escaping quotechar if doublequote is false.**
### Dialects
```python
+------------------+--------+-----------+--------------+
| | excel | excel_tab | unix_dialect |
+------------------+--------+-----------+--------------+
| delimiter | ',' | '\t' | ',' |
| quotechar | '"' | '"' | '"' |
| doublequote | True | True | True |
| skipinitialspace | False | False | False |
| lineterminator | '\r\n' | '\r\n' | '\n' |
| quoting | 0 | 0 | 1 |
| escapechar | None | None | None |
+------------------+--------+-----------+--------------+
```
### Read Rows from CSV File
```python
def read_csv_file(filename):
with open(filename, encoding='utf-8', newline='') as file:
return csv.reader(file, delimiter=';')
return csv.reader(file)
```
* **If `'newline=""'` is not specified, then newlines embedded inside quoted fields will not be interpreted correctly.**
@ -1654,7 +1687,7 @@ def read_csv_file(filename):
```python
def write_to_csv_file(filename, rows):
with open(filename, 'w', encoding='utf-8', newline='') as file:
writer = csv.writer(file, delimiter=';')
writer = csv.writer(file)
writer.writerows(rows)
```
@ -2138,7 +2171,7 @@ Table
from tabulate import tabulate
import csv
with open(<filename>, encoding='utf-8', newline='') as file:
lines = csv.reader(file, delimiter=';')
lines = csv.reader(file)
headers = [header.title() for header in next(lines)]
table = tabulate(lines, headers)
print(table)

38
index.html
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@ -1466,11 +1466,41 @@ os.replace(<span class="hljs-keyword">from</span>, to) <span class="hl
</code></pre>
<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
&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 a row as list of strings.</span>
</code></pre>
<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>, ...)
&lt;writer&gt;.writerow(&lt;collection&gt;)
&lt;writer&gt;.writerows(&lt;coll_of_coll&gt;)
</code></pre>
<h3 id="parameters">Parameters</h3>
<ul>
<li><strong><code class="python hljs"><span class="hljs-string">'dialect'</span></code> - Master parameter that sets the default values.</strong></li>
<li><strong><code class="python hljs"><span class="hljs-string">'delimiter'</span></code> - A one-character string used to separate fields.</strong></li>
<li><strong><code class="python hljs"><span class="hljs-string">'quotechar'</span></code> - Character for quoting fields that contain special characters.</strong></li>
<li><strong><code class="python hljs"><span class="hljs-string">'doublequote'</span></code> - Whether quotechars inside fields get doubled or escaped.</strong></li>
<li><strong><code class="python hljs"><span class="hljs-string">'skipinitialspace'</span></code> - Whether whitespace after delimiter gets stripped.</strong></li>
<li><strong><code class="python hljs"><span class="hljs-string">'lineterminator'</span></code> - How does writer terminate lines.</strong></li>
<li><strong><code class="python hljs"><span class="hljs-string">'quoting'</span></code> - Controls the amount of quoting: 0 - as necessary, 1 - all.</strong></li>
<li><strong><code class="python hljs"><span class="hljs-string">'escapechar'</span></code> - Character for escaping quotechar if doublequote is false.</strong></li>
</ul>
<h3 id="dialects">Dialects</h3>
<pre><code class="python language-python hljs">+------------------+--------+-----------+--------------+
| | excel | excel_tab | unix_dialect |
+------------------+--------+-----------+--------------+
| delimiter | <span class="hljs-string">','</span> | <span class="hljs-string">'\t'</span> | <span class="hljs-string">','</span> |
| quotechar | <span class="hljs-string">'"'</span> | <span class="hljs-string">'"'</span> | <span class="hljs-string">'"'</span> |
| doublequote | <span class="hljs-keyword">True</span> | <span class="hljs-keyword">True</span> | <span class="hljs-keyword">True</span> |
| skipinitialspace | <span class="hljs-keyword">False</span> | <span class="hljs-keyword">False</span> | <span class="hljs-keyword">False</span> |
| lineterminator | <span class="hljs-string">'\r\n'</span> | <span class="hljs-string">'\r\n'</span> | <span class="hljs-string">'\n'</span> |
| quoting | <span class="hljs-number">0</span> | <span class="hljs-number">0</span> | <span class="hljs-number">1</span> |
| escapechar | <span class="hljs-keyword">None</span> | <span class="hljs-keyword">None</span> | <span class="hljs-keyword">None</span> |
+------------------+--------+-----------+--------------+
</code></pre>
<h3 id="readrowsfromcsvfile">Read Rows from CSV File</h3>
<pre><code class="python language-python hljs"><span class="hljs-function"><span class="hljs-keyword">def</span> <span class="hljs-title">read_csv_file</span><span class="hljs-params">(filename)</span>:</span>
<span class="hljs-keyword">with</span> open(filename, encoding=<span class="hljs-string">'utf-8'</span>, newline=<span class="hljs-string">''</span>) <span class="hljs-keyword">as</span> file:
<span class="hljs-keyword">return</span> csv.reader(file, delimiter=<span class="hljs-string">';'</span>)
<span class="hljs-keyword">return</span> csv.reader(file)
</code></pre>
<ul>
<li><strong>If <code class="python hljs"><span class="hljs-string">'newline=""'</span></code> is not specified, then newlines embedded inside quoted fields will not be interpreted correctly.</strong></li>
@ -1478,7 +1508,7 @@ os.replace(<span class="hljs-keyword">from</span>, to) <span class="hl
<h3 id="writerowstocsvfile">Write Rows to CSV File</h3>
<pre><code class="python language-python hljs"><span class="hljs-function"><span class="hljs-keyword">def</span> <span class="hljs-title">write_to_csv_file</span><span class="hljs-params">(filename, rows)</span>:</span>
<span class="hljs-keyword">with</span> open(filename, <span class="hljs-string">'w'</span>, encoding=<span class="hljs-string">'utf-8'</span>, newline=<span class="hljs-string">''</span>) <span class="hljs-keyword">as</span> file:
writer = csv.writer(file, delimiter=<span class="hljs-string">';'</span>)
writer = csv.writer(file)
writer.writerows(rows)
</code></pre>
<h2 id="json"><a href="#json" name="json">#</a>JSON</h2>
@ -1681,7 +1711,7 @@ lock.release()
value = getattr(&lt;object&gt;, <span class="hljs-string">'&lt;attr_name&gt;'</span>)
setattr(&lt;object&gt;, <span class="hljs-string">'&lt;attr_name&gt;'</span>, value)
</code></pre>
<h3 id="parameters">Parameters</h3>
<h3 id="parameters-1">Parameters</h3>
<pre><code class="python language-python hljs"><span class="hljs-keyword">from</span> inspect <span class="hljs-keyword">import</span> signature
&lt;sig&gt; = signature(&lt;function&gt;)
no_of_params = len(&lt;sig&gt;.parameters)
@ -1835,7 +1865,7 @@ pyplot.clf() <span class="hljs-comment"># Clears figure.</span>
<span class="hljs-keyword">from</span> tabulate <span class="hljs-keyword">import</span> tabulate
<span class="hljs-keyword">import</span> csv
<span class="hljs-keyword">with</span> open(&lt;filename&gt;, encoding=<span class="hljs-string">'utf-8'</span>, newline=<span class="hljs-string">''</span>) <span class="hljs-keyword">as</span> file:
lines = csv.reader(file, delimiter=<span class="hljs-string">';'</span>)
lines = csv.reader(file)
headers = [header.title() <span class="hljs-keyword">for</span> header <span class="hljs-keyword">in</span> next(lines)]
table = tabulate(lines, headers)
print(table)

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