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List, Dict, Set - big changes
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‎README.md‎

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@@ -21,37 +21,37 @@ Contents
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Main
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----
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```python
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if __name__ == '__main__': # Skips next line if file was imported.
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main() # Runs `def main(): ...` function.
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if __name__ == '__main__': # Skips indented lines of code if file was imported.
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main() # Executes user-defined `def main(): ...` function.
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```
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List
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----
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```python
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<list> = [<el_1>, <el_2>, ...] # Creates a list object. Also list(<collection>).
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<list> = [<el_1>, <el_2>, ...] # Creates a new list object. Also list(<collection>).
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```
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```python
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<el> = <list>[index] # First index is 0. Last -1. Allows assignments.
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<el> = <list>[index] # First index is 0, last -1. Also `<list>[i] = <el>`.
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<list> = <list>[<slice>] # Also <list>[from_inclusive : to_exclusive : ±step].
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```
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```python
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<list>.append(<el>) # Appends element to the end. Also <list> += [<el>].
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<list>.extend(<collection>) # Appends elements to the end. Also <list> += <coll>.
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<list>.append(<el>) # Appends element to the end. Also `<list> += [<el>]`.
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<list>.extend(<collection>) # Appends multiple elements. Also `<list> += <coll>`.
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```
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```python
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<list>.sort() # Sorts the elements in ascending order.
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<list>.reverse() # Reverses the order of list's elements.
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<list> = sorted(<collection>) # Returns a new list with sorted elements.
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<iter> = reversed(<list>) # Returns reversed iterator of elements.
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<list>.sort(reverse=False) # Sorts the elements of the list in ascending order.
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<list>.reverse() # Reverses the order of elements. Takes linear time.
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<list> = sorted(<collection>) # Returns a new sorted list. Accepts `reverse=True`.
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<iter> = reversed(<list>) # Returns reversed iterator. Also list(<iterator>).
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```
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```python
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<el> = max(<collection>) # Returns largest element. Also min(<el_1>, ...).
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<num> = sum(<collection>) # Returns sum of elements. Also math.prod(<coll>).
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<el> = max(<collection>) # Returns the largest element. Also min(<el_1>, ...).
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<num> = sum(<collection>) # Returns a sum of elements. Also math.prod(<coll>).
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```
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```python
@@ -70,7 +70,7 @@ flatter_list = list(itertools.chain.from_iterable(<list>))
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<int> = <list>.index(<el>) # Returns index of the first occurrence or raises ValueError.
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<el> = <list>.pop() # Removes and returns item from the end or at index if passed.
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<list>.insert(<int>, <el>) # Inserts item at passed index and moves the rest to the right.
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<list>.remove(<el>) # Removes first occurrence of the item or raises ValueError.
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<list>.remove(<el>) # Removes the first occurrence or raises ValueError exception.
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<list>.clear() # Removes all list's items. Also works on dictionary and set.
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```
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@@ -88,16 +88,16 @@ Dictionary
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```
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```python
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value = <dict>.get(key, default=None) # Returns default argument if key is missing.
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value = <dict>.get(key, default=None) # Returns argument default if key is missing.
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value = <dict>.setdefault(key, default=None) # Returns and writes default if key is missing.
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<dict> = collections.defaultdict(<type>) # Returns a dict with default value `<type>()`.
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<dict> = collections.defaultdict(lambda: 1) # Returns a dict with default value 1.
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<dict> = collections.defaultdict(<type>) # Dict with automatic default value `<type>()`.
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<dict> = collections.defaultdict(lambda: 1) # Dictionary with automatic default value 1.
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```
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```python
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<dict> = dict(<collection>) # Creates a dict from coll. of key-value pairs.
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<dict> = dict(zip(keys, values)) # Creates a dict from two collections.
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<dict> = dict.fromkeys(keys [, value]) # Creates a dict from collection of keys.
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<dict> = dict(zip(keys, values)) # Creates a dictionary from two collections.
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<dict> = dict.fromkeys(keys [, value]) # Creates a dictionary from collection of keys.
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```
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```python
@@ -120,32 +120,32 @@ value = <dict>.pop(key) # Removes item or raises KeyErro
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Set
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---
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```python
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<set> = {<el_1>, <el_2>, ...} # Use `set()` for empty set.
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<set> = {<el_1>, <el_2>, ...} # Coll. of unique items. Also set(), set(<coll>).
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```
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```python
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<set>.add(<el>) # Or: <set> |= {<el>}
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<set>.update(<collection> [, ...]) # Or: <set> |= <set>
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<set>.add(<el>) # Adds item to the set. Also `<set> |= {<el>}`.
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<set>.update(<collection> [, ...]) # Adds items to the set. Also `<set> |= <set>`.
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```
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```python
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<set> = <set>.union(<coll.>) # Or: <set> | <set>
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<set> = <set>.intersection(<coll.>) # Or: <set> & <set>
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<set> = <set>.difference(<coll.>) # Or: <set> - <set>
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<set> = <set>.symmetric_difference(<coll.>) # Or: <set> ^ <set>
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<bool> = <set>.issubset(<coll.>) # Or: <set> <= <set>
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<bool> = <set>.issuperset(<coll.>) # Or: <set> >= <set>
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<set> = <set>.union(<coll>) # Returns a set of all items. Also <set> | <set>.
133+
<set> = <set>.intersection(<coll>) # Returns all shared items. Also <set> & <set>.
134+
<set> = <set>.difference(<coll>) # Returns set's unique items. Also <set> - <set>.
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<set> = <set>.symmetric_difference(<coll>) # Returns non-shared items. Also <set> ^ <set>.
136+
<bool> = <set>.issuperset(<coll>) # Returns False if collection has unique items.
137+
<bool> = <set>.issubset(<coll>) # Is collection a superset? Also <set> <= <set>.
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```
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```python
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<el> = <set>.pop() # Raises KeyError if empty.
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<set>.remove(<el>) # Raises KeyError if missing.
143-
<set>.discard(<el>) # Doesn't raise an error.
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<el> = <set>.pop() # Removes and returns an item or raises KeyError.
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<set>.remove(<el>) # Removes the item or raises KeyError if missing.
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<set>.discard(<el>) # Same as remove() but it doesn't raise an error.
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```
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### Frozen Set
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* **Is immutable and hashable.**
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* **That means it can be used as a key in a dictionary or as an element in a set.**
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* **That means it can be used as a key in a dictionary or as an item in a set.**
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```python
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<frozenset> = frozenset(<collection>)
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```

‎index.html‎

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<body>
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<header>
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<aside>September 16, 2025</aside>
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<aside>October 5, 2025</aside>
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<a href="https://gto76.github.io" rel="author">Jure Šorn</a>
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</header>
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<div><h2 id="main"><a href="#main" name="main">#</a>Main</h2><pre><code class="python language-python hljs"><span class="hljs-keyword">if</span> __name__ == <span class="hljs-string">'__main__'</span>: <span class="hljs-comment"># Skips next line if file was imported.</span>
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main() <span class="hljs-comment"># Runs `def main(): ...` function.</span>
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<div><h2 id="main"><a href="#main" name="main">#</a>Main</h2><pre><code class="python language-python hljs"><span class="hljs-keyword">if</span> __name__ == <span class="hljs-string">'__main__'</span>: <span class="hljs-comment"># Skips indented lines of code if file was imported.</span>
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main() <span class="hljs-comment"># Executes user-defined `def main(): ...` function.</span>
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</code></pre></div>
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<div><h2 id="list"><a href="#list" name="list">#</a>List</h2><pre><code class="python language-python hljs">&lt;list&gt; = [&lt;el_1&gt;, &lt;el_2&gt;, ...] <span class="hljs-comment"># Creates a list object. Also list(&lt;collection&gt;).</span>
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<div><h2 id="list"><a href="#list" name="list">#</a>List</h2><pre><code class="python language-python hljs">&lt;list&gt; = [&lt;el_1&gt;, &lt;el_2&gt;, ...] <span class="hljs-comment"># Creates a new list object. Also list(&lt;collection&gt;).</span>
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</code></pre></div>
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<pre><code class="python language-python hljs">&lt;el&gt; = &lt;list&gt;[index] <span class="hljs-comment"># First index is 0. Last -1. Allows assignments.</span>
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<pre><code class="python language-python hljs">&lt;el&gt; = &lt;list&gt;[index] <span class="hljs-comment"># First index is 0, last -1. Also `&lt;list&gt;[i] = &lt;el&gt;`.</span>
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&lt;list&gt; = &lt;list&gt;[&lt;slice&gt;] <span class="hljs-comment"># Also &lt;list&gt;[from_inclusive : to_exclusive : ±step].</span>
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</code></pre>
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<pre><code class="python language-python hljs">&lt;list&gt;.append(&lt;el&gt;) <span class="hljs-comment"># Appends element to the end. Also &lt;list&gt; += [&lt;el&gt;].</span>
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&lt;list&gt;.extend(&lt;collection&gt;) <span class="hljs-comment"># Appends elements to the end. Also &lt;list&gt; += &lt;coll&gt;.</span>
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<pre><code class="python language-python hljs">&lt;list&gt;.append(&lt;el&gt;) <span class="hljs-comment"># Appends element to the end. Also `&lt;list&gt; += [&lt;el&gt;]`.</span>
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&lt;list&gt;.extend(&lt;collection&gt;) <span class="hljs-comment"># Appends multiple elements. Also `&lt;list&gt; += &lt;coll&gt;`.</span>
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</code></pre>
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<pre><code class="python language-python hljs">&lt;list&gt;.sort() <span class="hljs-comment"># Sorts the elements in ascending order.</span>
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&lt;list&gt;.reverse() <span class="hljs-comment"># Reverses the order of list's elements.</span>
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&lt;list&gt; = sorted(&lt;collection&gt;) <span class="hljs-comment"># Returns a new list with sorted elements.</span>
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&lt;iter&gt; = reversed(&lt;list&gt;) <span class="hljs-comment"># Returns reversed iterator of elements.</span>
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<pre><code class="python language-python hljs">&lt;list&gt;.sort(reverse=<span class="hljs-keyword">False</span>) <span class="hljs-comment"># Sorts the elements of the list in ascending order.</span>
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&lt;list&gt;.reverse() <span class="hljs-comment"># Reverses the order of elements. Takes linear time.</span>
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&lt;list&gt; = sorted(&lt;collection&gt;) <span class="hljs-comment"># Returns a new sorted list. Accepts `reverse=True`.</span>
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&lt;iter&gt; = reversed(&lt;list&gt;) <span class="hljs-comment"># Returns reversed iterator. Also list(&lt;iterator&gt;).</span>
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</code></pre>
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<pre><code class="python language-python hljs">&lt;el&gt; = max(&lt;collection&gt;) <span class="hljs-comment"># Returns largest element. Also min(&lt;el_1&gt;, ...).</span>
129-
&lt;num&gt; = sum(&lt;collection&gt;) <span class="hljs-comment"># Returns sum of elements. Also math.prod(&lt;coll&gt;).</span>
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<pre><code class="python language-python hljs">&lt;el&gt; = max(&lt;collection&gt;) <span class="hljs-comment"># Returns the largest element. Also min(&lt;el_1&gt;, ...).</span>
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&lt;num&gt; = sum(&lt;collection&gt;) <span class="hljs-comment"># Returns a sum of elements. Also math.prod(&lt;coll&gt;).</span>
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</code></pre>
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<pre><code class="python language-python hljs">elementwise_sum = [sum(pair) <span class="hljs-keyword">for</span> pair <span class="hljs-keyword">in</span> zip(list_a, list_b)]
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sorted_by_second = sorted(&lt;collection&gt;, key=<span class="hljs-keyword">lambda</span> el: el[<span class="hljs-number">1</span>])
@@ -143,7 +143,7 @@
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&lt;int&gt; = &lt;list&gt;.index(&lt;el&gt;) <span class="hljs-comment"># Returns index of the first occurrence or raises ValueError.</span>
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&lt;el&gt; = &lt;list&gt;.pop() <span class="hljs-comment"># Removes and returns item from the end or at index if passed.</span>
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&lt;list&gt;.insert(&lt;int&gt;, &lt;el&gt;) <span class="hljs-comment"># Inserts item at passed index and moves the rest to the right.</span>
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&lt;list&gt;.remove(&lt;el&gt;) <span class="hljs-comment"># Removes first occurrence of the item or raises ValueError.</span>
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&lt;list&gt;.remove(&lt;el&gt;) <span class="hljs-comment"># Removes the first occurrence or raises ValueError exception.</span>
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&lt;list&gt;.clear() <span class="hljs-comment"># Removes all list's items. Also works on dictionary and set.</span>
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</code></pre>
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<div><h2 id="dictionary"><a href="#dictionary" name="dictionary">#</a>Dictionary</h2><pre><code class="python language-python hljs">&lt;dict&gt; = {key_1: val_1, key_2: val_2, ...} <span class="hljs-comment"># Use `&lt;dict&gt;[key]` to get or set the value.</span>
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&lt;view&gt; = &lt;dict&gt;.values() <span class="hljs-comment"># Collection of values that reflects changes.</span>
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&lt;view&gt; = &lt;dict&gt;.items() <span class="hljs-comment"># Coll. of key-value tuples that reflects chgs.</span>
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</code></pre>
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<pre><code class="python language-python hljs">value = &lt;dict&gt;.get(key, default=<span class="hljs-keyword">None</span>) <span class="hljs-comment"># Returns default argument if key is missing.</span>
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<pre><code class="python language-python hljs">value = &lt;dict&gt;.get(key, default=<span class="hljs-keyword">None</span>) <span class="hljs-comment"># Returns argument default if key is missing.</span>
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value = &lt;dict&gt;.setdefault(key, default=<span class="hljs-keyword">None</span>) <span class="hljs-comment"># Returns and writes default if key is missing.</span>
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&lt;dict&gt; = collections.defaultdict(&lt;type&gt;) <span class="hljs-comment"># Returns a dict with default value `&lt;type&gt;()`.</span>
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&lt;dict&gt; = collections.defaultdict(<span class="hljs-keyword">lambda</span>: <span class="hljs-number">1</span>) <span class="hljs-comment"># Returns a dict with default value 1.</span>
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&lt;dict&gt; = collections.defaultdict(&lt;type&gt;) <span class="hljs-comment"># Dict with automatic default value `&lt;type&gt;()`.</span>
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&lt;dict&gt; = collections.defaultdict(<span class="hljs-keyword">lambda</span>: <span class="hljs-number">1</span>) <span class="hljs-comment"># Dictionary with automatic default value 1.</span>
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</code></pre>
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<pre><code class="python language-python hljs">&lt;dict&gt; = dict(&lt;collection&gt;) <span class="hljs-comment"># Creates a dict from coll. of key-value pairs.</span>
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&lt;dict&gt; = dict(zip(keys, values)) <span class="hljs-comment"># Creates a dict from two collections.</span>
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&lt;dict&gt; = dict.fromkeys(keys [, value]) <span class="hljs-comment"># Creates a dict from collection of keys.</span>
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&lt;dict&gt; = dict(zip(keys, values)) <span class="hljs-comment"># Creates a dictionary from two collections.</span>
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&lt;dict&gt; = dict.fromkeys(keys [, value]) <span class="hljs-comment"># Creates a dictionary from collection of keys.</span>
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</code></pre>
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<pre><code class="python language-python hljs">&lt;dict&gt;.update(&lt;dict&gt;) <span class="hljs-comment"># Adds items. Replaces ones with matching keys.</span>
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value = &lt;dict&gt;.pop(key) <span class="hljs-comment"># Removes item or raises KeyError if missing.</span>
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[(<span class="hljs-string">'blue'</span>, <span class="hljs-number">3</span>), (<span class="hljs-string">'red'</span>, <span class="hljs-number">2</span>), (<span class="hljs-string">'yellow'</span>, <span class="hljs-number">1</span>)]
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</code></pre></div>
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<div><h2 id="set"><a href="#set" name="set">#</a>Set</h2><pre><code class="python language-python hljs">&lt;set&gt; = {&lt;el_1&gt;, &lt;el_2&gt;, ...} <span class="hljs-comment"># Use `set()` for empty set.</span>
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<div><h2 id="set"><a href="#set" name="set">#</a>Set</h2><pre><code class="python language-python hljs">&lt;set&gt; = {&lt;el_1&gt;, &lt;el_2&gt;, ...} <span class="hljs-comment"># Coll. of unique items. Also set(), set(&lt;coll&gt;).</span>
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</code></pre></div>
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<pre><code class="python language-python hljs">&lt;set&gt;.add(&lt;el&gt;) <span class="hljs-comment"># Or: &lt;set&gt; |= {&lt;el&gt;}</span>
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&lt;set&gt;.update(&lt;collection&gt; [, ...]) <span class="hljs-comment"># Or: &lt;set&gt; |= &lt;set&gt;</span>
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<pre><code class="python language-python hljs">&lt;set&gt;.add(&lt;el&gt;) <span class="hljs-comment"># Adds item to the set. Also `&lt;set&gt; |= {&lt;el&gt;}`.</span>
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&lt;set&gt;.update(&lt;collection&gt; [, ...]) <span class="hljs-comment"># Adds items to the set. Also `&lt;set&gt; |= &lt;set&gt;`.</span>
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</code></pre>
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<pre><code class="python language-python hljs">&lt;set&gt; = &lt;set&gt;.union(&lt;coll.&gt;) <span class="hljs-comment"># Or: &lt;set&gt; | &lt;set&gt;</span>
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&lt;set&gt; = &lt;set&gt;.intersection(&lt;coll.&gt;) <span class="hljs-comment"># Or: &lt;set&gt; &amp; &lt;set&gt;</span>
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&lt;set&gt; = &lt;set&gt;.difference(&lt;coll.&gt;) <span class="hljs-comment"># Or: &lt;set&gt; - &lt;set&gt;</span>
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&lt;set&gt; = &lt;set&gt;.symmetric_difference(&lt;coll.&gt;) <span class="hljs-comment"># Or: &lt;set&gt; ^ &lt;set&gt;</span>
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&lt;bool&gt; = &lt;set&gt;.issubset(&lt;coll.&gt;) <span class="hljs-comment"># Or: &lt;set&gt; &lt;= &lt;set&gt;</span>
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&lt;bool&gt; = &lt;set&gt;.issuperset(&lt;coll.&gt;) <span class="hljs-comment"># Or: &lt;set&gt; &gt;= &lt;set&gt;</span>
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<pre><code class="python language-python hljs">&lt;set&gt; = &lt;set&gt;.union(&lt;coll&gt;) <span class="hljs-comment"># Returns a set of all items. Also &lt;set&gt; | &lt;set&gt;.</span>
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&lt;set&gt; = &lt;set&gt;.intersection(&lt;coll&gt;) <span class="hljs-comment"># Returns all shared items. Also &lt;set&gt; &amp; &lt;set&gt;.</span>
185+
&lt;set&gt; = &lt;set&gt;.difference(&lt;coll&gt;) <span class="hljs-comment"># Returns set's unique items. Also &lt;set&gt; - &lt;set&gt;.</span>
186+
&lt;set&gt; = &lt;set&gt;.symmetric_difference(&lt;coll&gt;) <span class="hljs-comment"># Returns non-shared items. Also &lt;set&gt; ^ &lt;set&gt;.</span>
187+
&lt;bool&gt; = &lt;set&gt;.issuperset(&lt;coll&gt;) <span class="hljs-comment"># Returns False if collection has unique items.</span>
188+
&lt;bool&gt; = &lt;set&gt;.issubset(&lt;coll&gt;) <span class="hljs-comment"># Is collection a superset? Also &lt;set&gt; &lt;= &lt;set&gt;.</span>
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</code></pre>
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<pre><code class="python language-python hljs">&lt;el&gt; = &lt;set&gt;.pop() <span class="hljs-comment"># Raises KeyError if empty.</span>
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&lt;set&gt;.remove(&lt;el&gt;) <span class="hljs-comment"># Raises KeyError if missing.</span>
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&lt;set&gt;.discard(&lt;el&gt;) <span class="hljs-comment"># Doesn't raise an error.</span>
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<pre><code class="python language-python hljs">&lt;el&gt; = &lt;set&gt;.pop() <span class="hljs-comment"># Removes and returns an item or raises KeyError.</span>
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&lt;set&gt;.remove(&lt;el&gt;) <span class="hljs-comment"># Removes the item or raises KeyError if missing.</span>
192+
&lt;set&gt;.discard(&lt;el&gt;) <span class="hljs-comment"># Same as remove() but it doesn't raise an error.</span>
193193
</code></pre>
194194
<div><h3 id="frozenset">Frozen Set</h3><ul>
195195
<li><strong>Is immutable and hashable.</strong></li>
196-
<li><strong>That means it can be used as a key in a dictionary or as an element in a set.</strong></li>
196+
<li><strong>That means it can be used as a key in a dictionary or as an item in a set.</strong></li>
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</ul><pre><code class="python language-python hljs">&lt;frozenset&gt; = frozenset(&lt;collection&gt;)
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</code></pre></div>
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<footer>
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<aside>September 16, 2025</aside>
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<aside>October 5, 2025</aside>
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<a href="https://gto76.github.io" rel="author">Jure Šorn</a>
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</footer>
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