Use the tuple concatenation operation * with a tuple with one element (42,) as a right operand and the number of repetitions of this element as a left operand. For example, the expression (42,) * n creates the tuple (42, 42, 42, 42, 42) for n=5.
Let’s play with an interactive code shell before you’ll dive into the detailed solution!
Exercise: Initialize the tuple with n=20 placeholder elements -1 and run the code.
Problem Formulation
Next, you’ll learn about the more formal problem and dive into the step-by-step solution.
Problem: Given an integer n. How to initialize a tuple with n placeholder elements (e.g., 42)?
# n=0 --> ()
# n=1 --> (42,)
# n=5 --> (42, 42, 42, 42, 42)
Example 1 – Tuple Concatenation
Use the tuple concatenation operation * with a tuple with one element (42,) as right operand and the number of repetitions of this element as left operand. For example, the expression (42,) * n creates the tuple (42, 42, 42, 42, 42) for n=5.
n = 5
t = (42,) * n
print(t)
# (42, 42, 42, 42, 42)
Note that you cannot change the values of a tuple, once created, because unlike lists tuples are immutable. For example, trying to overwrite the third tuple value will yield a TypeError: 'tuple' object does not support item assignment.
>>> 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
Example 2 – N-Ary Tuple Concatenation
You can also use a generalization of the unary tuple concatenation — I call it n-ary tuple concatenation — to create a tuple of size n. For example, given a tuple t of size 3, you can create a tuple of size 9 by multiplying it with the integer 3 like so: t * 3.
Here’s an example:
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)
Example 3 – Tuple From List
This approach is simple: First, create a list of size n. Second, pass that list into the tuple() function to create a tuple of size n.
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, ...)
Recommended Tutorial: Create a List of Size n
Example 4 – Generator Expression (List Comprehension)
You can pass a generator expression into Python’s built-in tuple() function to dynamically create a tuple of elements, given another iterable. For example, the expression tuple(i**2 for i in range(10)) creates a tuple with ten square numbers.
Here’s the code snippet for copy&paste:
x = tuple(i**2 for i in range(10))
print(x)
# (0, 1, 4, 9, 16, 25, 36, 49, 64, 81)
In case you need some background on this terrific Python feature, check out my article on List Comprehension and my best-selling Python textbook on writing super condensed and concise Python code:
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https://www.sickgaming.net/blog/2022/08/...of-size-n/