richard
/
python-cheatsheet
mirror of https://github.com/gto76/python-cheatsheet.git
1
0
Fork 0
Code Issues Projects Releases Wiki Activity
Browse Source

Print, Input, Command line arguments

pull/170/head
Jure Šorn 1 year ago
parent
f149d662ed
commit
c95e741eff
2 changed files with 27 additions and 28 deletions
Split View
Diff Options
Show Stats Download Patch File Download Diff File
  1. 25
      README.md
  2. 30
      index.html

25
README.md
View File

@ -1509,24 +1509,23 @@ Print
print(<el_1>, ..., sep=' ', end='\n', file=sys.stdout, flush=False)
```
* **Use `'file=sys.stderr'` for messages about errors.**
* **Use `'flush=True'` to forcibly flush the stream.**
* **Stdout and stderr streams hold output in a buffer until they receive a string containing '\n' or '\r', buffer reaches 4096 characters, `'flush=True'` is used, or program exits.**
### Pretty Print
```python
from pprint import pprint
pprint(<collection>, width=80, depth=None, compact=False, sort_dicts=True)
```
* **Levels deeper than 'depth' get replaced by '...'.**
* **Each item is printed on its own line if collection takes up more than 'width' characters.**
* **Nested collections that are 'depth' levels deep get printed as '...'.**
Input
-----
**Reads a line from the user input or pipe if present.**
```python
<str> = input(prompt=None)
```
* **Trailing newline gets stripped.**
* **Reads a line from the user input or pipe if present (trailing newline gets stripped).**
* **Prompt string is printed to the standard output before reading input.**
* **Raises EOFError when user hits EOF (ctrl-d/ctrl-z⏎) or input stream gets exhausted.**
@ -1542,18 +1541,18 @@ arguments = sys.argv[1:]
### Argument Parser
```python
from argparse import ArgumentParser, FileType
p = ArgumentParser(description=<str>)
p.add_argument('-<short_name>', '--<name>', action='store_true') # Flag.
p.add_argument('-<short_name>', '--<name>', type=<type>) # Option.
p.add_argument('<name>', type=<type>, nargs=1) # First argument.
p.add_argument('<name>', type=<type>, nargs='+') # Remaining arguments.
p = ArgumentParser(description=<str>) # Returns a parser.
p.add_argument('-<short_name>', '--<name>', action='store_true') # Flag (defaults to False).
p.add_argument('-<short_name>', '--<name>', type=<type>) # Option (defaults to None).
p.add_argument('<name>', type=<type>, nargs=1) # Mandatory first argument.
p.add_argument('<name>', type=<type>, nargs='+') # Mandatory remaining args.
p.add_argument('<name>', type=<type>, nargs='*') # Optional arguments.
args = p.parse_args() # Exits on error.
value = args.<name>
<args> = p.parse_args() # Exits on parsing error.
<obj> = <args>.<name> # Returns `<type>(<arg>)`.
```
* **Use `'help=<str>'` to set argument description that will be displayed in help message.**
* **Use `'default=<el>'` to set argument's default value.**
* **Use `'default=<el>'` to set option's default value.**
* **Use `'type=FileType(<mode>)'` for files. Accepts 'encoding', but 'newline' is None.**

30
index.html
View File

@ -54,7 +54,7 @@
<body>
<header>
<aside>January 20, 2024</aside>
<aside>January 22, 2024</aside>
<a href="https://gto76.github.io" rel="author">Jure Šorn</a>
</header>
@ -1282,21 +1282,21 @@ sys.exit(&lt;int&gt;) <span class="hljs-comment"># Exits with
<ul>
<li><strong>Use <code class="python hljs"><span class="hljs-string">'file=sys.stderr'</span></code> for messages about errors.</strong></li>
<li><strong>Use <code class="python hljs"><span class="hljs-string">'flush=True'</span></code> to forcibly flush the stream.</strong></li>
<li><strong>Stdout and stderr streams hold output in a buffer until they receive a string containing '\n' or '\r', buffer reaches 4096 characters, <code class="python hljs"><span class="hljs-string">'flush=True'</span></code> is used, or program exits.</strong></li>
</ul>
<div><h3 id="prettyprint">Pretty Print</h3><pre><code class="python language-python hljs"><span class="hljs-keyword">from</span> pprint <span class="hljs-keyword">import</span> pprint
pprint(&lt;collection&gt;, width=<span class="hljs-number">80</span>, depth=<span class="hljs-keyword">None</span>, compact=<span class="hljs-keyword">False</span>, sort_dicts=<span class="hljs-keyword">True</span>)
</code></pre></div>
<ul>
<li><strong>Levels deeper than 'depth' get replaced by '…'.</strong></li>
<li><strong>Each item is printed on its own line if collection takes up more than 'width' characters.</strong></li>
<li><strong>Nested collections that are 'depth' levels deep get printed as '…'.</strong></li>
</ul>
<div><h2 id="input"><a href="#input" name="input">#</a>Input</h2><p><strong>Reads a line from the user input or pipe if present.</strong></p><pre><code class="python language-python hljs">&lt;str&gt; = input(prompt=<span class="hljs-keyword">None</span>)
<div><h2 id="input"><a href="#input" name="input">#</a>Input</h2><pre><code class="python language-python hljs">&lt;str&gt; = input(prompt=<span class="hljs-keyword">None</span>)
</code></pre></div>
<ul>
<li><strong>Trailing newline gets stripped.</strong></li>
<li><strong>Reads a line from the user input or pipe if present (trailing newline gets stripped).</strong></li>
<li><strong>Prompt string is printed to the standard output before reading input.</strong></li>
<li><strong>Raises EOFError when user hits EOF (ctrl-d/ctrl-z⏎) or input stream gets exhausted.</strong></li>
</ul>
@ -1306,19 +1306,19 @@ arguments = sys.argv[<span class="hljs-number">1</span>:]
</code></pre></div>
<div><h3 id="argumentparser">Argument Parser</h3><pre><code class="python language-python hljs"><span class="hljs-keyword">from</span> argparse <span class="hljs-keyword">import</span> ArgumentParser, FileType
p = ArgumentParser(description=&lt;str&gt;)
p.add_argument(<span class="hljs-string">'-&lt;short_name&gt;'</span>, <span class="hljs-string">'--&lt;name&gt;'</span>, action=<span class="hljs-string">'store_true'</span>) <span class="hljs-comment"># Flag.</span>
p.add_argument(<span class="hljs-string">'-&lt;short_name&gt;'</span>, <span class="hljs-string">'--&lt;name&gt;'</span>, type=&lt;type&gt;) <span class="hljs-comment"># Option.</span>
p.add_argument(<span class="hljs-string">'&lt;name&gt;'</span>, type=&lt;type&gt;, nargs=<span class="hljs-number">1</span>) <span class="hljs-comment"># First argument.</span>
p.add_argument(<span class="hljs-string">'&lt;name&gt;'</span>, type=&lt;type&gt;, nargs=<span class="hljs-string">'+'</span>) <span class="hljs-comment"># Remaining arguments.</span>
p = ArgumentParser(description=&lt;str&gt;) <span class="hljs-comment"># Returns a parser.</span>
p.add_argument(<span class="hljs-string">'-&lt;short_name&gt;'</span>, <span class="hljs-string">'--&lt;name&gt;'</span>, action=<span class="hljs-string">'store_true'</span>) <span class="hljs-comment"># Flag (defaults to False).</span>
p.add_argument(<span class="hljs-string">'-&lt;short_name&gt;'</span>, <span class="hljs-string">'--&lt;name&gt;'</span>, type=&lt;type&gt;) <span class="hljs-comment"># Option (defaults to None).</span>
p.add_argument(<span class="hljs-string">'&lt;name&gt;'</span>, type=&lt;type&gt;, nargs=<span class="hljs-number">1</span>) <span class="hljs-comment"># Mandatory first argument.</span>
p.add_argument(<span class="hljs-string">'&lt;name&gt;'</span>, type=&lt;type&gt;, nargs=<span class="hljs-string">'+'</span>) <span class="hljs-comment"># Mandatory remaining args.</span>
p.add_argument(<span class="hljs-string">'&lt;name&gt;'</span>, type=&lt;type&gt;, nargs=<span class="hljs-string">'*'</span>) <span class="hljs-comment"># Optional arguments.</span>
args = p.parse_args() <span class="hljs-comment"># Exits on error.</span>
value = args.&lt;name&gt;
&lt;args&gt; = p.parse_args() <span class="hljs-comment"># Exits on parsing error.</span>
&lt;obj&gt; = &lt;args&gt;.&lt;name&gt; <span class="hljs-comment"># Returns `&lt;type&gt;(&lt;arg&gt;)`.</span>
</code></pre></div>
<ul>
<li><strong>Use <code class="python hljs"><span class="hljs-string">'help=&lt;str&gt;'</span></code> to set argument description that will be displayed in help message.</strong></li>
<li><strong>Use <code class="python hljs"><span class="hljs-string">'default=&lt;el&gt;'</span></code> to set argument's default value.</strong></li>
<li><strong>Use <code class="python hljs"><span class="hljs-string">'default=&lt;el&gt;'</span></code> to set option's default value.</strong></li>
<li><strong>Use <code class="python hljs"><span class="hljs-string">'type=FileType(&lt;mode&gt;)'</span></code> for files. Accepts 'encoding', but 'newline' is None.</strong></li>
</ul>
<div><h2 id="open"><a href="#open" name="open">#</a>Open</h2><p><strong>Opens the file and returns a corresponding file object.</strong></p><pre><code class="python language-python hljs">&lt;file&gt; = open(&lt;path&gt;, mode=<span class="hljs-string">'r'</span>, encoding=<span class="hljs-keyword">None</span>, newline=<span class="hljs-keyword">None</span>)
@ -2932,7 +2932,7 @@ $ deactivate <span class="hljs-comment"># Deactivates the activ
<footer>
<aside>January 20, 2024</aside>
<aside>January 22, 2024</aside>
<a href="https://gto76.github.io" rel="author">Jure Šorn</a>
</footer>

Write Preview
Loading…
Cancel
Save