Array comparison and set operations in Ruby - Step-by-Step Execution

Concept Flow - Array comparison and set operations

Start with two arrays

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Compare arrays for equality

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Perform set operations

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Union

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Result output

Start with two arrays, compare them, then perform union, intersection, and difference operations to get new arrays.

Execution Sample

Ruby

a = [1, 2, 3, 4]
b = [3, 4, 5, 6]

puts a == b
puts (a | b).inspect
puts (a & b).inspect
puts (a - b).inspect

This code compares two arrays for equality and shows their union, intersection, and difference.

Execution Table

Step	Action	Expression	Result	Explanation
1	Compare arrays a and b	a == b	false	Arrays differ in elements, so equality is false
2	Union of a and b	a | b	[1, 2, 3, 4, 5, 6]	Combines unique elements from both arrays
3	Intersection of a and b	a & b	[3, 4]	Elements common to both arrays
4	Difference of a and b	a - b	[1, 2]	Elements in a not in b
5	End	-	-	All operations completed

💡 All set operations performed and results displayed

Variable Tracker

Variable	Start	After Step 1	After Step 2	After Step 3	After Step 4	Final
a	[1, 2, 3, 4]	[1, 2, 3, 4]	[1, 2, 3, 4]	[1, 2, 3, 4]	[1, 2, 3, 4]	[1, 2, 3, 4]
b	[3, 4, 5, 6]	[3, 4, 5, 6]	[3, 4, 5, 6]	[3, 4, 5, 6]	[3, 4, 5, 6]	[3, 4, 5, 6]
a == b	N/A	false	false	false	false	false
a | b	N/A	N/A	[1, 2, 3, 4, 5, 6]	[1, 2, 3, 4, 5, 6]	[1, 2, 3, 4, 5, 6]	[1, 2, 3, 4, 5, 6]
a & b	N/A	N/A	N/A	[3, 4]	[3, 4]	[3, 4]
a - b	N/A	N/A	N/A	N/A	[1, 2]	[1, 2]

Key Moments - 3 Insights

Why does 'a == b' return false even though some elements are the same?

Because '==' checks if arrays have the same elements in the same order. Here, a and b differ in elements and order, so result is false (see step 1 in execution_table).

What does the '|' operator do with arrays?

It creates a union of unique elements from both arrays, removing duplicates (see step 2 in execution_table).

Why does 'a - b' only show elements from a not in b?

Because '-' subtracts elements of b from a, leaving only those unique to a (see step 4 in execution_table).

Visual Quiz - 3 Questions

Look at the execution table, what is the result of 'a & b' at step 3?

A [1, 2]

B [3, 4]

C [5, 6]

D [1, 2, 3, 4, 5, 6]

💡 Hint

Check the 'Result' column for step 3 in execution_table

At which step does the union of arrays a and b get computed?

A Step 1

B Step 3

C Step 2

D Step 4

💡 Hint

Look for the action 'Union of a and b' in execution_table

If array b was changed to [1, 2, 3, 4], what would 'a == b' return?

A true

B false

C nil

D error

💡 Hint

Refer to variable_tracker and key_moments about array equality

Concept Snapshot

Array comparison and set operations in Ruby:
- Use '==' to check if arrays are equal (same elements, same order)
- Use '|' for union (unique elements from both arrays)
- Use '&' for intersection (common elements)
- Use '-' for difference (elements in first array not in second)
- Results are new arrays without modifying originals

Full Transcript

This visual execution trace shows how Ruby compares two arrays and performs set operations. First, it checks if arrays a and b are equal using '==', which returns false because their elements differ. Then it computes the union with '|', combining unique elements from both arrays. Next, it finds the intersection with '&', showing elements common to both. Finally, it calculates the difference with '-', showing elements in a not in b. Variables remain unchanged throughout. Key moments clarify why equality requires exact match and how set operators work. The quiz tests understanding of these steps.