value = <dict>.get(key, default=None) # Returns default if key is missing.
value = <dict>.setdefault(key, default=None) # Returns and writes default if key is missing.
<dict> = collections.defaultdict(<type>) # Returns a dict with default value of type.
<dict> = collections.defaultdict(<type>) # Returns a dict with default value `<type>()`.
<dict> = collections.defaultdict(lambda: 1) # Returns a dict with default value 1.
```
@ -353,7 +353,7 @@ Regex
import re
<str> = re.sub(<regex>, new, text, count=0) # Substitutes all occurrences with 'new'.
<list> = re.findall(<regex>, text) # Returns all occurrences as strings.
<list> = re.split(<regex>, text, maxsplit=0) # Use brackets in regex to include the matches.
<list> = re.split(<regex>, text, maxsplit=0) # Add brackets around regex to include matches.
<Match> = re.search(<regex>, text) # Searches for first occurrence of the pattern.
<Match> = re.match(<regex>, text) # Searches only at the beginning of the text.
<iter> = re.finditer(<regex>, text) # Returns all occurrences as Match objects.
@ -1400,7 +1400,7 @@ finally:
```
* **Code inside the `'else'` block will only be executed if `'try'` block had no exceptions.**
* **Code inside the `'finally'` block will always be executed (unless a signal is received).**
* **All variables that are initialized in executed blocks are also visible in all subsequent blocks, as well as outside the try/except clause (only function blocks delimit scope).**
* **All variables that are initialized in executed blocks are also visible in all subsequent blocks, as well as outside the try/except clause (only function block delimits scope).**
* **To catch signals use `'signal.signal(signal_number, <func>)'`.**
### Catching Exceptions
@ -2452,7 +2452,7 @@ import logging
```
```python
logging.basicConfig(filename=<path>) # Configures the root logger.
logging.basicConfig(filename=<path>) # Configures the root logger (see Setup).
logging.debug/info/warning/error/critical(<str>) # Logs to the root logger.
<Logger> = logging.getLogger(__name__) # Logger named after the module.
<Logger>.<level>(<str>) # Messages propagate to the root logger.
@ -2463,7 +2463,7 @@ logging.debug/info/warning/error/critical(<str>) # Logs to the root logger.
```python
logging.basicConfig(
filename=None, # Logs to console (stderr) by default.
format='%(levelname)s:%(name)s:%(message)s', # Add `%(asctime)s` for datetime.
format='%(levelname)s:%(name)s:%(message)s', # Add `%(asctime)s` for local datetime.
level=logging.WARNING, # Drops messages with lower priority.
handlers=[logging.StreamHandler()] # Uses FileHandler if filename is set.
<pre><codeclass="python language-python hljs">value = <dict>.get(key, default=<spanclass="hljs-keyword">None</span>) <spanclass="hljs-comment"># Returns default if key is missing.</span>
value = <dict>.setdefault(key, default=<spanclass="hljs-keyword">None</span>) <spanclass="hljs-comment"># Returns and writes default if key is missing.</span>
<dict> = collections.defaultdict(<type>) <spanclass="hljs-comment"># Returns a dict with default value of type.</span>
<dict> = collections.defaultdict(<type>) <spanclass="hljs-comment"># Returns a dict with default value `<type>()`.</span>
<dict> = collections.defaultdict(<spanclass="hljs-keyword">lambda</span>: <spanclass="hljs-number">1</span>) <spanclass="hljs-comment"># Returns a dict with default value 1.</span>
</code></pre>
<pre><codeclass="python language-python hljs"><dict> = dict(<collection>) <spanclass="hljs-comment"># Creates a dict from coll. of key-value pairs.</span>
<div><h2id="regex"><ahref="#regex"name="regex">#</a>Regex</h2><pre><codeclass="python language-python hljs"><spanclass="hljs-keyword">import</span> re
<str> = re.sub(<regex>, new, text, count=<spanclass="hljs-number">0</span>) <spanclass="hljs-comment"># Substitutes all occurrences with 'new'.</span>
<list> = re.findall(<regex>, text) <spanclass="hljs-comment"># Returns all occurrences as strings.</span>
<list> = re.split(<regex>, text, maxsplit=<spanclass="hljs-number">0</span>) <spanclass="hljs-comment"># Use brackets in regex to include the matches.</span>
<list> = re.split(<regex>, text, maxsplit=<spanclass="hljs-number">0</span>) <spanclass="hljs-comment"># Add brackets around regex to include matches.</span>
<Match> = re.search(<regex>, text) <spanclass="hljs-comment"># Searches for first occurrence of the pattern.</span>
<Match> = re.match(<regex>, text) <spanclass="hljs-comment"># Searches only at the beginning of the text.</span>
<iter> = re.finditer(<regex>, text) <spanclass="hljs-comment"># Returns all occurrences as Match objects.</span>
<li><strong>Code inside the <codeclass="python hljs"><spanclass="hljs-string">'else'</span></code> block will only be executed if <codeclass="python hljs"><spanclass="hljs-string">'try'</span></code> block had no exceptions.</strong></li>
<li><strong>Code inside the <codeclass="python hljs"><spanclass="hljs-string">'finally'</span></code> block will always be executed (unless a signal is received).</strong></li>
<li><strong>All variables that are initialized in executed blocks are also visible in all subsequent blocks, as well as outside the try/except clause (only function blocks delimit scope).</strong></li>
<li><strong>All variables that are initialized in executed blocks are also visible in all subsequent blocks, as well as outside the try/except clause (only function block delimits scope).</strong></li>
<li><strong>To catch signals use <codeclass="python hljs"><spanclass="hljs-string">'signal.signal(signal_number, <func>)'</span></code>.</strong></li>
<pre><codeclass="python language-python hljs">logging.basicConfig(filename=<path>) <spanclass="hljs-comment"># Configures the root logger.</span>
<pre><codeclass="python language-python hljs">logging.basicConfig(filename=<path>) <spanclass="hljs-comment"># Configures the root logger (see Setup).</span>
logging.debug/info/warning/error/critical(<str>) <spanclass="hljs-comment"># Logs to the root logger.</span>
<Logger> = logging.getLogger(__name__) <spanclass="hljs-comment"># Logger named after the module.</span>
<Logger>.<level>(<str>) <spanclass="hljs-comment"># Messages propagate to the root logger.</span>
Jure Šorn
1 year ago