So if I have a bash array:
ar=( "one" "two" "three" "four")
What is the best way to make a new array such that it looks like this:
ar-new=( "one" "one two" "one two three" "one two three four" )
I cooked up something that use a for loop inside a for loop and using seq. Is there a better/more elegant way to accomplish this?
Here's another way:
for ((i=1; i<=${#ar[@]}; i++ ))
do
ar_new+=("${ar[*]:0:$i} ")
done
Depending on what, exactly, you are trying to accomplish, you can do it in one loop without any external commands.
Using an arithmetic for loop:
typeset -a ar
ar=("one" "two" "three" "four")
typeset -a ar_new=()
p=""
for (( i=0; i < ${#ar[@]}; ++i )); do
p="$p${p:+ }${ar[$i]}"
ar_new[$i]="$p"
done
Using a string for loop loop (might not work for large arrays?, might be slower for large arrays):
typeset -a ar
ar=("one" "two" "three" "four")
typeset -a ar_new=()
p=""
for s in "${ar[@]}"; do
p="$p${p:+ }$s"
ar_new=("${ar_new[@]}" "$p")
done
