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[Tut] How to Create a Python Tuple of Size n? - xSicKxBot - 08-26-2022
How to Create a Python Tuple of Size n?
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<div class="kksr-legend" style="font-size: 19.2px;"> 5/5 – (1 vote) </div>
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<p class="has-global-color-8-background-color has-background">Use the tuple concatenation operation <code>*</code> with a tuple with one element <code>(42,)</code> as a right operand and the number of repetitions of this element as a left operand. For example, the expression <code>(42,) * n</code> creates the tuple <code>(42, 42, 42, 42, 42)</code> for <code>n=5</code>.</p>
<p>Let’s play with an interactive code shell before you’ll dive into the detailed solution!</p>
<p> <iframe loading="lazy" src="https://trinket.io/embed/python/2f2185e99e" width="100%" height="356" frameborder="0" marginwidth="0" marginheight="0" allowfullscreen></iframe> </p>
<p><em><strong>Exercise</strong>: Initialize the tuple with <code>n=20</code> placeholder elements <code>-1</code> and run the code. </em></p>
<hr class="wp-block-separator has-css-opacity"/>
<h2>Problem Formulation</h2>
<p>Next, you’ll learn about the more formal problem and dive into the step-by-step solution.</p>
<p><strong>Problem</strong>: Given an integer <code>n</code>. How to initialize a tuple with <code>n</code> placeholder elements (e.g., <code>42</code>)?</p>
<pre class="EnlighterJSRAW" data-enlighter-language="python" data-enlighter-theme="" data-enlighter-highlight="" data-enlighter-linenumbers="" data-enlighter-lineoffset="" data-enlighter-title="" data-enlighter-group=""># n=0 --> ()
# n=1 --> (42,)
# n=5 --> (42, 42, 42, 42, 42)</pre>
<h2>Example 1 – Tuple Concatenation</h2>
<p>Use the tuple concatenation operation <code>*</code> with a tuple with one element <code>(42,)</code> as right operand and the number of repetitions of this element as left operand. For example, the expression <code>(42,) * n</code> creates the tuple <code>(42, 42, 42, 42, 42)</code> for <code>n=5</code>.</p>
<pre class="EnlighterJSRAW" data-enlighter-language="python" data-enlighter-theme="" data-enlighter-highlight="2" data-enlighter-linenumbers="" data-enlighter-lineoffset="" data-enlighter-title="" data-enlighter-group="">n = 5
t = (42,) * n
print(t)
# (42, 42, 42, 42, 42)</pre>
<p>Note that you cannot change the values of a tuple, once created, because unlike lists tuples are <a rel="noreferrer noopener" href="https://blog.finxter.com/mutable-vs-immutable-objects-in-python/" data-type="post" data-id="204090" target="_blank">immutable</a>. For example, trying to overwrite the third tuple value will yield a <code>TypeError: 'tuple' object does not support item assignment</code>.</p>
<pre class="EnlighterJSRAW" data-enlighter-language="python" data-enlighter-theme="" data-enlighter-highlight="2,6" data-enlighter-linenumbers="" data-enlighter-lineoffset="" data-enlighter-title="" data-enlighter-group="">>>> x = (42,) * 5
>>> x[0] = 'Alice'
Traceback (most recent call last): File "<pyshell#6>", line 1, in <module> x[0] = 'Alice'
TypeError: 'tuple' object does not support item assignment</pre>
<h2>Example 2 – N-Ary Tuple Concatenation</h2>
<p class="has-global-color-8-background-color has-background">You can also use a generalization of the <strong><em>unary</em></strong> tuple concatenation — I call it <strong><em>n-ary tuple concatenation</em></strong> — to create a tuple of size <code>n</code>. For example, given a tuple <code>t</code> of size 3, you can create a tuple of size 9 by multiplying it with the integer 3 like so: <code>t * 3</code>. </p>
<p>Here’s an example:</p>
<pre class="EnlighterJSRAW" data-enlighter-language="python" data-enlighter-theme="" data-enlighter-highlight="2" data-enlighter-linenumbers="" data-enlighter-lineoffset="" data-enlighter-title="" data-enlighter-group="">simple_tuple = ('Alice', 42, 3.14)
complex_tuple = simple_tuple * 3 print(complex_tuple)
# ('Alice', 42, 3.14, 'Alice', 42, 3.14, 'Alice', 42, 3.14)</pre>
<h2>Example 3 – Tuple From List</h2>
<p class="has-global-color-8-background-color has-background">This approach is simple: First, create a list of size n. Second, pass that list into the <code><a href="https://blog.finxter.com/python-tuple/" data-type="post" data-id="21575" target="_blank" rel="noreferrer noopener">tuple()</a></code> function to create a tuple of size <code>n</code>. </p>
<pre class="EnlighterJSRAW" data-enlighter-language="python" data-enlighter-theme="" data-enlighter-highlight="" data-enlighter-linenumbers="" data-enlighter-lineoffset="" data-enlighter-title="" data-enlighter-group="">n = 100 # 1. Create list of size n
lst = [42] * n # 2. Change value in (mutable) list
lst[2] = 'Alice' # 3. Create tuple from list AFTER modification
t = tuple(lst) # 4. Print tuple
print(t)
# (42, 42, 'Alice', 42, 42, ...)</pre>
<p class="has-base-background-color has-background"><strong>Recommended Tutorial</strong>: <a href="https://blog.finxter.com/how-to-create-a-python-list-of-size-n/" data-type="post" data-id="10466">Create a List </a><a href="https://blog.finxter.com/how-to-create-a-python-list-of-size-n/" data-type="post" data-id="10466" target="_blank" rel="noreferrer noopener">o</a><a href="https://blog.finxter.com/how-to-create-a-python-list-of-size-n/" data-type="post" data-id="10466">f Size n</a></p>
</p>
<h2>Example 4 – Generator Expression (List Comprehension)</h2>
<p class="has-global-color-8-background-color has-background">You can pass a <a href="https://blog.finxter.com/python-one-line-generator/" data-type="post" data-id="13194" target="_blank" rel="noreferrer noopener">generator expression</a> into Python’s built-in <code><a href="https://blog.finxter.com/python-tuple/" data-type="post" data-id="21575" target="_blank" rel="noreferrer noopener">tuple()</a></code> function to dynamically create a tuple of elements, given another iterable. For example, the expression <code>tuple(i**2 for i in range(10))</code> creates a tuple with ten square numbers.</p>
<p>Here’s the code snippet for copy&paste:</p>
<pre class="EnlighterJSRAW" data-enlighter-language="python" data-enlighter-theme="" data-enlighter-highlight="" data-enlighter-linenumbers="" data-enlighter-lineoffset="" data-enlighter-title="" data-enlighter-group="">x = tuple(i**2 for i in range(10))
print(x)
# (0, 1, 4, 9, 16, 25, 36, 49, 64, 81)</pre>
<p>In case you need some background on this terrific Python feature, check out my article on <a rel="noreferrer noopener" href="https://blog.finxter.com/list-comprehension/" data-type="post" data-id="1171" target="_blank">List Comprehension</a> and my <a rel="noreferrer noopener" href="https://pythononeliners.com/" data-type="URL" data-id="https://pythononeliners.com/" target="_blank">best-selling</a> Python textbook on writing super condensed and concise Python code:</p>
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