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32 lines
798 B
Markdown
32 lines
798 B
Markdown
# Swap Two Items in a Vector
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If you want to replace the value at an index in a vector, you can use the
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`assoc` function supplied by `clojure.core` like so:
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```clojure
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> (assoc [5 6 7 8] 1 9)
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; [5 9 7 8]
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```
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Likewise, if you want to replace two items in a vector, you can extend the
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above like so:
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```clojure
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> (assoc [5 6 7 8] 1 2 2 4)
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; [5 2 4 8]
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```
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We can take advantage of that second example to construct a function that
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will swap two values:
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```clojure
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(defn swap
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[items i j]
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(assoc items i (items j) j (items i)))
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```
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This function will break on values of `i` and `j` that are out of the bounds
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of `items`, but dealing with that is left as an exercise to the reader.
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[source](http://stackoverflow.com/questions/5979538/what-is-the-idiomatic-way-to-swap-two-elements-in-a-vector)
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