I've two arrays, say:
arr1=("one" "two" "three")
arr2=("two" "four" "six")
What would be the best way to get union of these two arrays in Bash?
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codeforester
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user2436428
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1Actual union (without dupes) or simply both arrays concatenated? – Mr. Llama Oct 15 '15 at 16:27
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Actual union (without duplicates) – user2436428 Oct 15 '15 at 16:29
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1In zsh you can just use `typeset -U arr`, pretty sure there isn't such an easy way in bash. – Kevin Oct 15 '15 at 16:38
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@Kevin how to use `typeset -U arr`? – denysdovhan Oct 19 '17 at 11:43
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1@denysdovhan `typeset -u arr; arr=(a b a c); echo $arr # prints a b c`. – Kevin Oct 19 '17 at 15:46
2 Answers
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First, combine the arrays:
arr3=("${arr1[@]}" "${arr2[@]}")
Then, apply the solution from this post to deduplicate them:
# Declare an associative array
declare -A arr4
# Store the values of arr3 in arr4 as keys.
for k in "${arr3[@]}"; do arr4["$k"]=1; done
# Extract the keys.
arr5=("${!arr4[@]}")
This assumes bash 4+.
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5No need for `arr3`: just use `for k in "${arr1[@]}" "${arr2[@]}"` – Andrea Corbellini Oct 15 '15 at 16:41
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Prior to bash 4,
while read -r; do
arr+=("$REPLY")
done < <( printf '%s\n' "${arr1[@]}" "${arr2[@]}" | sort -u )
sort -u performs a dup-free union on its input; the while loop just puts everything back in an array.
chepner
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