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25 lines
920 B
Markdown
25 lines
920 B
Markdown
# Combinations Of Items From A Sequence
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Sometimes we want all combinations of items from a list. For instance, we
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may have 5 people and we want to know all the ways that we can unique pair
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up 2 people from that group of 5. What we want is the number of
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combinations of 2 people from the 5.
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The
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[clojure/math.combinatorics](https://github.com/clojure/math.combinatorics)
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library provides a `combinations` function that gives us exactly that
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functionality.
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```clojure
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(use '[clojure.math.combinatorics :as combo])
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(combo/combinations ["Liz", "Tracy", "Kenneth", "Jack", "Jenna"] 2)
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; (("Liz" "Tracy") ("Liz" "Kenneth") ("Liz" "Jack")
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; ("Liz" "Jenna") ("Tracy" "Kenneth") ("Tracy" "Jack")
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; ("Tracy" "Jenna") ("Kenneth" "Jack") ("Kenneth" "Jenna")
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; ("Jack" "Jenna"))
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```
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The `combinations` function takes a list of items and then a number for the
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size of the grouping combinations that it is supposed to produce.
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