[Tut] How to Create a Python Tuple of Size n?

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How to Create a Python Tuple of Size n?

5/5 – (1 vote)

Use the tuple concatenation operation

Code:

*

with a tuple with one element

Code:

(42,)

as a right operand and the number of repetitions of this element as a left operand. For example, the expression

Code:

(42,) * n

creates the tuple

Code:

(42, 42, 42, 42, 42)

for

Code:

n=5

.

Let’s play with an interactive code shell before you’ll dive into the detailed solution!

https://trinket.io/embed/python/2f2185e99e

Exercise: Initialize the tuple with

Code:

n=20

placeholder elements

Code:

-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

Code:

n

. How to initialize a tuple with

Code:

n

placeholder elements (e.g.,

Code:

42

)?

Code:

# n=0 --> () # n=1 --> (42,) # n=5 --> (42, 42, 42, 42, 42)

Example 1 – Tuple Concatenation

Use the tuple concatenation operation

Code:

*

with a tuple with one element

Code:

(42,)

as right operand and the number of repetitions of this element as left operand. For example, the expression

Code:

(42,) * n

creates the tuple

Code:

(42, 42, 42, 42, 42)

for

Code:

n=5

.

Code:

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

Code:

TypeError: 'tuple' object does not support item assignment

.

Code:

>>> 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

Code:

n

. For example, given a tuple

Code:

t

of size 3, you can create a tuple of size 9 by multiplying it with the integer 3 like so:

Code:

t * 3

.

Here’s an example:

Code:

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

Code:

tuple()

function to create a tuple of size

Code:

n

.

Code:

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 Listof Size n

Example 4 – Generator Expression (List Comprehension)

You can pass a generator expression into Python’s built-in

Code:

tuple()

function to dynamically create a tuple of elements, given another iterable. For example, the expression

Code:

tuple(i**2 for i in range(10))

creates a tuple with ten square numbers.

Here’s the code snippet for copy&paste:

Code:

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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