How to Create a Python Tuple of Size n?

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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
# (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

# ('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
# (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))
# (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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