How do I create a newArray containing only the unique elements present in Array?
Ex: ARRAY contains elements aa ab bb aa ab cc at ARRAY[0-5] respectively.
When I print newARRAY, I want only aa ab bb cc at newARRAY[0-3] respectively.
I've searched stack overflow for a while now and nothing is solving my problem. I tried to do newARRAY=$(ARRAY[@] | sort -u | uniq, but duplicated elements still exist.
To get the unique elements of arr and assuming that no element contains newlines:
$ printf "%s\n" "${arr[@]}" | sort -u
aa
ab
bb
cc
To get a NUL-separated list that works even if there were newlines:
$ printf "%s\0" "${arr[@]}" | sort -uz
aaabbbcc
(This, of course, looks ugly on a terminal because it doesn't display NULs.)
To capture the result in newArr:
$ newArr=(); while IFS= read -r -d '' x; do newArr+=("$x"); done < <(printf "%s\0" "${arr[@]}" | sort -uz)
After running the above, we can use declare to verify that newArr is the array that we want:
$ declare -p newArr
declare -a newArr=([0]="aa" [1]="ab" [2]="bb" [3]="cc")
For those who prefer their code spread over multiple lines, the above can be rewritten as:
newArr=()
while IFS= read -r -d '' x
do
newArr+=("$x")
done < <(printf "%s\0" "${arr[@]}" | sort -uz)
Don't use all caps for your variable names. The system and the shell use all caps for their names and you don't want to accidentally overwrite one of them.
You can use an associatve array to keep track of elements you've seen:
#!/bin/bash
ARRAY=(aa ab bb aa ab cc)
unset dupes # ensure it's empty
declare -A dupes
for i in "${ARRAY[@]}"; do
if [[ -z ${dupes[$i]} ]]; then
NEWARRAY+=("$i")
fi
dupes["$i"]=1
done
unset dupes # optional
printf "[%s]" "${ARRAY[@]}"
echo
printf "[%s]" "${NEWARRAY[@]}"
echo
