Engineering Python · Data & Control

Tuples and Sets

In Engineering Python because some sequences must not change and some collections only care about unique membership — tuple and set.

A tuple is an ordered sequence that you cannot assign into. A set holds unique items and answers `in` quickly, with no index. Concatenating two tuples is just `+` — useful in a lab, not the whole idea.

Engineering Python
Easy level
4 concepts

1Tuples are ordered and immutable

Parentheses build a tuple: `(10, 20, 30)`. Indexing works the same as a list. Assigning `t[0] = 1` raises TypeError — that is the point of a tuple.

Use a tuple when the group is a fixed record (name, marks) that later code should not rewrite in place.

No diagram — the idea is carried by the prose, code block or coding lab.

List vs tuple vs set
Kind	Order	Change in place	Index
list	yes	yes	yes
tuple	yes	no	yes
set	no	add/remove	no

Fixed record

row = ("Asha", 86)
print(row[0], row[1])

What happens if you run `t[0] = 1` on `t = (2, 3)`?

TypeError — tuples do not support item assignment
t becomes (1, 3)
t becomes [1, 3]

Immutability is the difference from a list.

2Concatenating tuples

`+` joins two tuples into a new tuple. The originals stay unchanged. A lab that says "concatenate member tuples" wants this, not a rewrite of either input.

Figure. + joins two tuples into a new tuple. left + right is ("Patel", "Riya", "Mehta", "Arun"). left afterwards is still ("Patel", "Riya") — + does not rewrite either input.

Join two records

left = ("Patel", "Riya")
right = ("Mehta", "Arun")
print(left + right)

Join two member tuples

left is ("Patel", "Riya") and right is ("Mehta", "Arun"). What is left + right, and what is left afterwards?

left + right("Patel", "Riya", "Mehta", "Arun")
left after +("Patel", "Riya") — unchanged

Pro tip. + builds a new tuple. It does not rewrite either input.

3Sets store unique membership

Curly braces with values (not key:value pairs) build a set: `{1, 2, 2}` is `{1, 2}`. Duplicates disappear.

`x in s` asks membership. There is no `s[0]` — sets are not sequences. `|` is union; `&` is intersection.

Figure. {2, 4, 2, 6} is {2, 4, 6} — the second 2 disappears. 4 in seen is True. {2, 4} | {4, 8} is {2, 4, 8}; union keeps 4 once. There is no s[0] — sets are not sequences.

Unique then combine

seen = {2, 4, 2, 6}
print(seen)
print(4 in seen)
print({2, 4} | {4, 8})

Drop the duplicate, then union

seen starts as {2, 4, 2, 6}. What is seen, is 4 in it, and what is {2, 4} | {4, 8}?

{2, 4, 2, 6}{2, 4, 6}
4 in seenTrue
{2, 4} | {4, 8}{2, 4, 8}

Pro tip. The second 2 disappears. Union keeps 4 once.

4Lab: join tuples, test a set

Concatenate two member tuples and print a set membership test.

Figure. Concatenate ("Patel", "Riya") with ("Mehta", "Arun") — the joined tuple holds Riya. Then 4 in {2, 4, 6} is True. Tuple + builds a new tuple; a set answers in and drops duplicates.

Takeaway

Hold thisConcatenate two member tuples and print a set membership test.

Coding lab. Members and a unique set runs in the app, with checks on your output.

Notes

In Engineering Python because some sequences must not change and some collections only care about unique membership — tuple and set.
Parentheses build a tuple: `(10, 20, 30)`. Indexing works the same as a list. Assigning `t[0] = 1` raises TypeError — that is the point of a tuple.
`+` joins two tuples into a new tuple. The originals stay unchanged. A lab that says "concatenate member tuples" wants this, not a rewrite of either input.

Exam traps & shortcuts

Run one cell at a time and read stdout before changing more lines.
Names are labels for values; rebinding a name does not rewrite old prints.

Recap

Tuples keep order and refuse item assignment; sets keep unique membership.

Tuples are ordered and immutable: Parentheses build a tuple: `(10, 20, 30)`. Indexing works the same as a list. Assigning `t[0] = 1` raises TypeError — that is the point of a tuple.
Concatenating tuples: `+` joins two tuples into a new tuple. The originals stay unchanged. A lab that says "concatenate member tuples" wants this, not a rewrite of either input.
Sets store unique membership: Curly braces with values (not key:value pairs) build a set: `{1, 2, 2}` is `{1, 2}`. Duplicates disappear.
Lab: join tuples, test a set: Concatenate two member tuples and print a set membership test.

Practise Tuples and Sets

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A 2-question practice set that ends the chapter
1 quick check with worked explanations
Timed mocks scored with the real marking scheme
Readiness tracked per topic, kept on your device

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